Underpinning of York Minster
|
|
- Cornelius Kelley
- 5 years ago
- Views:
Transcription
1 Underpinning of York Minster La Reprise en Sous-oeuvre des Fondations de la Cath6drale d'york J.A. LORD Project Director, Ove Arup & Partners, London, United Kingdom S Y N O P S I S F o l l o w i n g a s u r v e y of Y o r k M i n s t e r, s e r i o u s c r a c k i n g, p a r t i c u l a r l y of the C e n t r a l T o w e r ( w e i g h i n g 1 8, t onnes) a n d t h e E a s t W a l l, w a s f o u n d to be d u e to d i f f e r e n t i a l s e t t l e m e n t s. A s i t e i n v e s t i g a t i o n w a s c a r r i e d o u t to a s s e s s t h e s t r e n g t h of t h e s o i l b e n e a t h the f o u n d a t i o n s a n d to p e r m i t t h e d e s i g n of s u i t a b l e u n d e r p i n n i n g. V a r i o u s u n d e r p i n n i n g s c h e m e s that w e r e c o n s i d e r e d for the C e n t r a l T o w e r a n d t h e r e a s o n s for t h e i r r e j e c t i o n are d i s c u s s e d. T h e s c h e m e a d o p t e d is d e s c r i b e d, i n c l u d i n g t h e l o a d - s e t t l e m e n t b e h a v i o u r o f c o n c r e t e b a s e s, a c t i v a t e d b y flat jacks, i n s t a l l e d to c o n s o l i d a t e t h e s o i l b e n e a t h t h e n e w f o u n d a t i o n s. T h e s e t t l e m e n t r e s p o n s e of t h e T o w e r t o t h e v a r i o u s s t a g e s o f u n d e r p i n n i n g is p r e s e n t e d. S i m i l a r u n d e r p i n n i n g w a s c a r r i e d out o n t h e t w o W e s t e r n T o w e r s, e a c h w e i g h i n g 1 0, t o n n e s. T h e u n d e r p i n n i n g of t h e E a s t w a l l of the M i n s t e r by m e a n s of h e a d i n g s is a l s o d e s c r i b e d. S e t t l e m e n t m e a s u r e m e n t s d u r i n g t h e c o u r s e of this w o r k a r e p r e s e n t e d a n d t h e e f f e c t s of a l a y e r of l a m i n a t e d c l a y b e n e a t h the f o u n d a t i o n s a r e d i s c u s s e d I N T R O D U C T I O N Y o r k M i n s t e r (see Fig. 1 a n d Fig. 2) is o n e of the l a r g e s t m e d i e v a l b u i l d i n g s in N o r t h e r n E u r o p e. A l t h o u g h p a r t d a t e s f r o m t h e 11th c e n t u r y, t h e b u i l d i n g, in t h e f o r m t h a t e x i s t s today, w a s c o m p l e t e d in E x t e r n a l l y, its m o s t n o t i c e a b l e f e a t u r e s a r e t h e C e n t r a l T o w e r a n d t w o W e s t e r n T o w e r s a l l a b o u t 6 0 m h i g h. T h e c o m b i n e d l e n g t h of t h e N a v e a n d C h o i r is m a n d t h e i r f l o o r to c e i l i n g h e i g h t is o v e r 30m. In 1966 an i n s p e c t i o n of the M i n s t e r ' s c o n d i t i o n b y t h e n e w l y a p p o i n t e d S u r v e y o r of t h e F a b r i c, B e r n a r d F e i l d e n, r e v e a l e d c r a c k i n g a n d s e v e r e d i s t o r t i o n of the m a s o n r y a r o u n d t h e C e n t r a l T o w e r. A n e x p l o r a t o r y e x c a v a t i o n a d j a c e n t to t h e N.E. p i e r of t h e T o w e r r e v e a l e d p o o r q u a l i t y m a s o n r y f o u n d a t i o n s, b a d l y d i s t o r t e d a n d c r a c k e d as a r e s u l t of l a r g e d i f f e r e n t i a l s e t t l e m e n t s. f ~ 1 ROMAN FOUNDATIONS i l H NORMAN ( C " * ) FOUNDATIONS AND WALLS t ~ J EARLY 12TH CENTURY FO UNDATIONS I H LATE 12TH CENTURY FO UNDATIONS 15TH CENTURY FOUND ATIO NS & WALLS Borehole K8 Pier Number J18 «J19 BH10 LADY CHAPEL < K19 EAST WALL + < L19 BH7 M18^BHTI % M19 F i g. 1.. ROMAN HEADQUARTERS BUILDING BH6 / P l a n s h o w i n g t h e r e l a t i o n s h i p of t h e p r e s e n t Y o r k M i n s t e r to the u n d e r l y i n g R o m a n a n d N o r m a n c o n s t r u c t i o n a n d t h e l o c a t i o n of t h e b o r e h o l e s. 119
2 CENTRAL TOWER EAST WALL mm mod Fig. 2 E l s e w h e r e in t h e M i n s t e r, t h e E a s t W a l l w a s f o u n d to b e o v e r m m o u t of p l u m b, and c r a c k s in t h e 19th c e n t u r y r e p a i r s to the m a s o n r y i n d i c a t e d t h a t o u t w a r d m o v e m e n t w a s c o n t i n u i n g. A full d e s c r i p t i o n o f t h e s t r u c t u r a l d e f e c t s to the M i n s t e r is g i v e n b y D o w r i c k a n d B e c k m a n n (1971). O n the b a s i s of a d e t a i l e d s u r v e y of t h o s e p a r t s of the M i n s t e r w h i c h c o u l d r e a s o n a b l y b e e x p e c t e d to h a v e b e e n c o n s t r u c t e d to a level, e.g. p l i n t h a n d s t r i n g c o u r s e s, it w a s c o n c l u d e d t h a t the p i e r s of t h e C e n t r a l T o w e r h a d s e t t l e d u p to m m a n d t h e W e s t e r n T o w e r s up to 7 5 m m w i t h r e s p e c t to the N a v e. F u r t h e r m o r e, if the o b s e r v e d d i f f e r e n t i a l s e t t l e m e n t s of the N.W. a n d S.W. p i e r s of the C e n t r a l T o w e r r e l a t i v e to t h e t w o e a s t e r n p i e r s w e r e a p p l i e d to a t h r e e - d i m e n s i o n a l s t r u c t u r a l m o d e l t h e z o n e s of h i g h t e n s i o n p r e d i c t e d b y t h e a n a l y s i s c o r r e s p o n d e d e x a c t l y w i t h p o s i t i o n s of major" c r a c k s. I t w a s t h e r e f o r e c o n c l u d e d t h a t t h e c r a c k i n g of t h e C e n t r a l T o w e r w a s e n t i r e l y t h e r e s u l t of d i f f e r e n t i a l s e t t l e m e n t s of t h e piers. S I T E I N V E S T I G A T I O N Reddish brown fine- grained Indicates distance out of plumb (mm) Indicates cracks BH1 BH3 B H 5 BH10 BH8 PIT S e c t i o n t h r o u g h n a v e a n d c h o i r s h o w i n g m o v e m e n t a n d c r a c k i n g o f t h e s t r u c t u r e u n d e r l y i n g s o i l s t r a t a. a n d the r e p r e s e n t i n g t h e w e a t h e r e d s u r f a c e of t h e u n d e r l y i n g B u n t e r s a n d s t o n e b e d r o c k. A d j a c e n t to t h e N.W. p i e r t h e r e w a s a b o u t 8m of m a d e g r o u n d, w h i c h p r o v i d e d a p o s s i b l e e x p l a n a t i o n o f the e x c e s s i v e s e t t l e m e n t of this pier. ( S u b s e q u e n t l a R o m a n d r a i n w a s a l s o f o u n d to p a s s b e n e a t h this p i e r ). T h e v a r i a t i o n w i t h d e p t h o f t h e A t t e r b e r g L i m i t s a n d n a t u r a l m o i s t u r e c o n t e n t of t h e u p p e r 14m o f n a t u r a l g r o u n d are g i v e n in Fig. 3. The u p p e r 2m of c l a y is of m e d i u m to h i g h p l a s t i c i t y w h e r e a s t h e B o u l d e r C l a y is of l o w p l a s t i c i t y. T h e s h e a r s t r e n g t h of t h e c l a y i n c r e a s e d f r o m a b o u t k N / m 2 i m m e d i a t e l y b e n e a t h the m a d e g r o u n d to o v e r k N / m at 1 2 m b e l o w g r o u n d level. C o n s o l i d a t i o n t e s t s o n s a m p l e s of t h e b r o w n s i l t y c l a y i n d i c a t e d a c o e f f i c i e n t of c o m p r e s s i b i l i t y o f a b o u t 1.5 x 1 0 " ^ m 2/kN M O I S T U R E C O N T E N T % i i i I p Floor level Inside Minster o Ground level outside LEGEND Minster Liquid Limit x Plastic Limit 14 Natural Moisture Content 13 FILL T h e site i n v e s t i g a t i o n, c a r r i e d o u t to i n v e s t i g a t e the s t r a t a on w h i c h t h e M i n s t e r w a s founded, c o n s i s t e d of e l e v e n b o r e h o l e s w h o s e l o c a t i o n s are s h o w n in Fig. 1. T h r e e b o r e h o l e s (Nos. 6, 8 a n d 11) o u t s i d e the e a s t e n d of the b u i l d i n g w e r e d o n e w i t h a s h e l l a n d a u g e r b o r i n g rig w h i l e the r e m a i n d e r w e r e r o t a r y c o r e d w i t h an e l e c t r i c a l l y d r i v e n B o y l e s ' B B S 10 r i g to m i n i m i s e v i b r a t i o n a n d n o i s e. T h e b o r e h o l e s i n d i c a t e d t h a t t h e r e w a s s o m e 3% to 4 ^ m of h i g h l y v a r i a b l e m a d e g r o u n d, t h e p r o d u c t o f c e n t u r i e s of h a b i t a t i o n a n d d e v e l o p m e n t on t h e site. This o v e r l a y n a t u r a l g r o u n d w h i c h c o n s i s t e d, as i n d i c a t e d in Fig. 2, of s o m e 3 t o 3 ^ m o f f i r m to s t i f f clay, b e c o m i n g v a r v e d a n d v e r y s a n d y at t h e b a s e (glacial lake d e p o s i t s ) o v e r l y i n g a b o u t l h to 1 1 m of s t i f f B o u l d e r C lay. A t a b o u t 1 8 m b e l o w g r o u n d level, d e n s e fine s a n d w a s e n c o u n t e r e d Fig Firm to stiff brown silty CLAY 11, v. ; * Firm to stiff brown laminated SILT & CLAY with layers of fine S A N D 10 + * 8. X * ' + + Yellow-brown fine S A N D --- E t 8 S! 7 * * > Stiff brown sandy \ \ + ^ 6 CLAY with fine & medium I gravel & occasional -. cobbles V (Boulder Clay) * + 1 M e +» + e 0 K + ~ > Dense reddish brown + fine S A N D -2 i T y p i c a l s o i l p r o f i l e a n d v a r i a t i o n of A t t e r b e r g L i m i t s w i t h d e p t h 120
3 A s a l o w e r i n g of t h e g r o u n d w a t e r t a b l e is o f t e n the c a u s e of s e t t l e m e n t of o l d b u i l d i n g s,p i e z o m e t e r s a n d s t a n d p i p e s w e r e I n s t a l l e d to s t u d y t h e g r o u n d w a t e r r e g i m e. M e a s u r e m e n t s in t h r e e a n c i e n t w e l l s in a d d i t i o n t o t h e s t a n d p i p e s s h o w e d a p e r c h e d w a t e r t a b l e in t h e m a d e g r o u n d a b o u t 3m b e l o w g r o u n d level. T h e p i e z o m e t e r s r e c o r d e d a h y d r o s t a t i c h e a d c o r r e s p o n d i n g t o a w a t e r t a b l e a b o u t 8m b e l o w g r o u n d level, l a r g e l y g o v e r n e d b y t h e l e v e l s of the R i v e r s O u s e and Foss, w h i c h w e r e r a i s e d w h e n l o c k s w e r e i n t r o d u c e d in t h e 17th c e n t u r y. It w a s t h e r e f o r e u n l i k e l y t h a t c h a n g e s in t h e l e v e l of t h e d e e p w a t e r t a b l e, o f s u f f i c i e n t m a g n i t u d e to c a u s e f o u n d a t i o n m o v e m e n t, h a d t a k e n p l a c e in t h e last t w o c e n t u r i e s. H I S T O R Y OF T H E S I T E T h e g r o u n d o n w h i c h t h e M i n s t e r w a s b u i l t is the h i g h e s t in Y o r k a n d w a s k n o w n to h a v e b e e n a p r i n c i p a l a r e a of h a b i t a t i o n d u r i n g R o m a n times. E x c a v a t i o n s d u r i n g t h e c o u r s e of t h e r e s t o r a t i o n w o r k d e s r i b e d b y P h i l l i p s (1975) r e v e a l e d t h a t t h e s i t e w a s c o v e r e d b y p a r t of t h e H e a d q u a r t e r s b u i l d i n g of the R o m a n l e g i o n s t a t i o n e d in Y o r k (see Fig. 1). U s e of the s i t e i m m e d i a t e l y a f t e r R o m a n o c c u p a t i o n is u n c e r t a i n, b u t in 1080 a n c i e n t r e c o r d s d e s c r i b e t h e c o n s t r u c t i o n o f a N o r m a n C h u r c h, to r e p l a c e a n e a r l i e r t i m b e r o n e t h a t h a d b u r n t d o w n in A n o t h e r f i r e in 1137 led to r e b u i l d i n g w i t h l o n g e r t r a n s e p t s (see Fig. 1). D u r i n g t h e 1 3 t h t h c e n t u r i e s, the M i n s t e r w a s g r a d u a l l y t r a n s f o r m e d i n t o its p r e s e n t form, b e g i n n i n g w i t h t h e r e b u i l d i n g of t h e t r a n s e p t s a n d C e n t r a l T o w e r in E a r l y E n g l i s h s t y l e b e t w e e n 1225 a n d A b o u t 1400, a t t e m p t s to r e s t y l e t h e f o u r m a i n p i e r s c a r r y i n g t h e C e n t r a l T o w e r in P e r p e n d i c u l a r style, led to its c o l l a p s e. R e b u i l d i n g w a s c o m p l e t e d in S E T T L E M E N T M E A S U R E M E N T S O n a c c o u n t of t h e p a r l o u s s t a t e of t h e M i n s t e r, it w a s d e c i d e d f r o m t h e o u t s e t to c o n t r o l all a s p e c t s of w o r k on t h e f o u n d a t i o n s b y r e f e r e n c e t o p r e c i s e m e a s u r e m e n t s of s e t t l e m e n t of the M i n s t e r a n d t h e m o v e m e n t of c r a c k s b y m e a n s of a D e m e c gauge. A c c o r d i n g l y, t w o b e n c h m a r k s w e r e i n s t a l l e d at t h e w e s t end, o n e i n s i d e the M i n s t e r a n d o n e o u t s i d e, f o u n d e d in t h e s a n d s t o n e, so t h a t s u b s e q u e n t l e v e l l i n g m e a s u r e m e n t s of the M i n s t e r c o u l d b e r e l a t e d to a s t a b l e datum. T H E C E N T R A L T O W E R F o u n d a t i o n A n a l y s i s In o r d e r to p r o v i d e m o r e r e l i a b l e i n f o r m a t i o n for t h e d e s i g n of t h e u n d e r p i n n i n g the o r i g i n a l e x p l o r a t o r y e x c a v a t i o n w a s e n l a r g e d to d e t e r m i n e t h e e x a c t s i z e a n d n a t u r e of t h e f o u n d a t i o n s on w h i c h t h e C e n t r a l T o w e r w a s c a r r i e d. T h e e x c a v a t i o n s r e v e a l e d t h a t the p i e r s w e r e b u i l t on r e m n a n t s of t h e w a l l s of the p r e v i o u s N o r m a n C h u r c h t h e m s e l v e s s u p p o r t e d b y s t r i p f o o t i n g s, the t o p s of w h i c h w e r e a b o u t 2m b e l o w the p r e s e n t f l o o r level. T h e N o r m a n f o o t i n g s w e r e e i t h e r 4m o r 6. 5 m w i d e, as s h o w n in Fig. 1, a n d w e r e a b o u t 2 m thick. In a n a l y s i n g the f o u n d a t i o n s it w a s d i f f i c u l t to a s s e s s the a r e a of the N o r m a n f o o t i n g s e f f e c t i v e l y s u p p o r t i n g the load o n e a c h p ier. S h e a r c r a c k s in t h e s t u b w a l l s a n d f o u n d a t i o n s c o r r e s p o n d e d e x a c t l y w i t h a 45 s p r e a d of l o a d f r o m t h e p i e r p e d e s t a l s so t h a t o n l y the f o o t i n g a r e a w i t h i n t h i s s p r e a d w a s a s s u m e d to be e f f e c t i v e, s u c h as t h a t f o r t h e N W P i e r in Fig. 4. T h e t h r u s t line f r o m the pier, c o m p u t e d by a s t r u c t u r a l a n a l y s i s of t h e t o w e r (see D o w r i c k a n d B e c k m a n n (1971)), w a s a s s e s s e d as b e i n g 0. 9 m f r o m t h e c e n t r e of area. M o d i f y i n g the e c c e n t r i c a l l y l o a d e d a r e a as r e c o m m e n d e d by M e y e r h o f (1951) a n d b y B r i n c h H a n s e n (1961) g a v e a v e r a g e b e a r i n g p r e s s u r e s of 720 k N / m 2 and 750 k N / m 2 r e s p e c t i v e l y f o r a p i e r l o a d of 4, t o n n e s. A s the u n d r a i n e d s h e a r s t r e n g t h of s a m p l e s of the s t i f f b r o w n clay, f r o m t h e same l e v e l as t h a t i m m e d i a t e l y b e n e a t h t h e f o u n d a t i o n s, w a s o n l y a b o u t 100 k N / m 2, t h e f a c t o r of s a f e t y a g a i n s t l o c a l s h e a r f a i l u r e w a s o b v i o u s l y low. H o w e v e r, this l a y e r c o u l d be e x p e c t e d to h a v e a h i g h e r s t r e n g t h i m m e d i a t e l y b e n e a t h the f o u n d a tions, h a v i n g b e e n h i g h l y c o n s o l i d a t e d in the p ast. F u r t h e r m o r e a n y zone of r u p t u r e w o u l d h a v e to p a s s t h r o u g h t h e b o u l d e r c l a y (see Fig. 4). S i m p l e a n a l y s i s i n d i c a t e d a f a c t o r of s a f e t y a g a i n s t b e a r i n g c a p a c i t y f a i l u r e of less t h a n 1.8, a l t h o u g h i n a c c u r a c i e s d u e to i-75m L e v e l l i n g p o i n t s, c o n s i s t i n g of s c r i b e d s teel s t r i p s, w e r e a t t a c h e d to e a c h of t h e f o u r p i e r s s u p p o r t i n g the C e n t r a l T o w e r a n d to a d j a c e n t p i e r s in t h e N a v e, T r a n s e p t s a n d Choir. S i m i l a r s t r i p s w e r e a t t a c h e d to p i e r s b e n e a t h the W e s t e r n T o w e r s a n d to t h e b u t t r e s s e s o u t s i d e the E a s t W a l l. P r e c i s e l e v e l m e a s u r e m e n t s w e r e t a k e n on e a c h p i e r t w i c e a w e e k w i t h an a u t o m a t i c i n s t r u m e n t r e a d i n g to 0. 2 m m t h r o u g h o u t t h e c o u r s e of t h e w o r k. E a c h of the t h r e e m a i n p r o b l e m a r e a s - t h e C e n t r a l Tower, t h e W e s t e r n T o w e r s a n d the E a s t W a l l w i l l n o w b e c o n s i d e r e d in turn. F i g. 4 S e c t i o n t h r o u g h f o u n d a t i o n s of N.W. a n d S.W. p i e r s of C e n t r a l T o w e r s h o w i n g c r a c k i n g a n d a s s u m e d l o a d - b e a r i n g a r e a of N.W. p i e r 121
4 (a) (b) (c) the a p p r o x i m a t e e s t i m a t e of t h e e f f e c t i v e l oad b e a r i n g a r e a t h e a s s u m p t i o n of z e r o s h e a r t r a n s f e r a c r o s s the s h e a r c r a c k s t h r o u g h t h e f o o t i n g s s i m p l i f i c a t i o n o f a z o n e of r u p t u r e w h i c h p a s s e s t h r o u g h the c l a y a n d s a n d l a y e r s and t h r o u g h b o u l d e r c l a y (d) t h e e f f e c t of a d j a c e n t f o u n d a t i o n s in s u r c h a r g i n g t h e g r o u n d m a d e t h e a c c u r a c y of s u c h an a n a l y s i s d i f f i c u l t to assess. N e v e r t h e l e s s, t h e d e f o r m a t i o n of the m a s o n r y f o o t i n g s a n d d i f f e r e n t i a l s e t t l e m e n t of m m c l e a r l y i n d i c a t e d t h a t t h e f o o t i n g s w e r e o v e r l o a d e d. A d d i t i o n a l s e t t l e m e n t r e c o r d e d w h e n t h e e x p l o r a t o r y e x c a v a t i o n s w e r e c a r r i e d o u t (as d i s c u s s e d later) e m p h a s i s e d t h e low m a r g i n o f safety. A n a t t e m p t w a s m a d e b y t h e a u t h o r to r e c o n s t r u c t t h e p a t t e r n of s e t t l e m e n t s of d i f f e r e n t p a r t s o f t h e s t r u c t u r e s i n c e 1080, b y a s s e s s i n g t h e l oads a n d i m p o s e d soil p r e s s u r e s for the d i f f e r e n t p h a s e s of b u i l d i n g a n d a p p l y i n g s o i l c o n s o l i d a t i o n d a t a m e a s u r e d in t h e l a b o r a t o r y tests. T h e d i f f e r e n t i a l s e t t l e m e n t s p r e d i c t e d in this w a y (see Fig. 5 - p r e v i o u s l y p r e s e n t e d by D o w r i c k & B e c k m a n n (1971)) c o r r e s p o n d e d r e m a r k a b l y w e l l w i t h t h o s e o b s e r v e d. a s s u m e d s a n d s t o n e at 9m depth. T h e i n c r e a s e d p i l e l e n g t h s f o l l o w i n g the s i t e i n v e s t i g a t i o n m a d e the m e t h o d v e r y e x p e n s i v e. P y n f o r d s : A n o t h e r c o m m o n m e t h o d of u n d e r p i n n i n g in t h e U. K., i n v o l v e s s u p p o r t i n g the s t r u c t u r e u s i n g P y n f o r d ' s t e c h n i q u e of " s t o o l s " w h i l s t a n e w f o u n d a t i o n is f o rmed. In this t e c h n i q u e, s t e e l s t o o l s a r e i n s e r t e d i n t o h o l e s c u t into t h e e x i s t i n g f o u n d a t i o n s in o r d e r t o s u p p o r t the s t r u c t u r e above, as i l l u s t r a t e d in Fig. 6(b)(i). O n c e t h e s t r u c t u r e has b e e n " p i n n e d up" in this w a y the m a s o n r y b e t w e e n t h e s t o o l s is r e m o v e d. R e i n f o r c e m e n t is t h e n t h r e a d e d t h r o u g h the s t o o l s a n d c o n c r e t e is p l a c e d to c r e a t e a r e i n f o r c e d c o n c r e t e raft. In t h e c a s e of the M i n s t e r the r a f t w a s t o b e s u p p o r t e d b y f o u r h a n d d u g p i l e s as s h o w n in Fig. 6(b) (ii). It w a s c o n s i d e r e d t h a t in v i e w of t h e r i s k of b e a r i n g c a p a c i t y f a i l u r e b e n e a t h t h e s t o o l s and t h e p r o b l e m s of c u t t i n g o u t m a s o n r y u p t o 6m w i d e beneath t h e p i e r s, this t e c h n i q u e w a s u n a c c e p t a b l e. TIME SCALE - YEARS A.D Fig. 5 H y p o t h e t i c a l r e c o n s t r u c t i o n of s e t t l e m e n t s s i n c e A.D. S c h e m e s f o r U n d e r p i n n i n g I n i t i a l l y v a r i o u s u n d e r p i n n i n g s c h e m e s, b a s e d on c o m m e r c i a l u n d e r p i n n i n g t e c h n i q u e s, w e r e c o n s i d e r e d. T h e s c h e m e s w e r e b a s e d o n the f i n d i n g s of the e x p l o r a t o r y e x c a v a t i o n a n d w e r e d r a w n up b e f o r e t h e i n f o r m a t i o n f r o m the site i n v e s t i g a t i o n w a s a v a i l a b l e. F o n d e d i l e - P a l l R a d i c e : T h i s is a w e l l - p r o v e n t e c h n i q u e for u n d e r p i n n i n g o l d b u i l d i n g s, in w h i c h m m d i a m e t e r i n c l i n e d p i l e s a r e i n s t a l l e d by r o t a r y c o r i n g t h r o u g h the m a s o n r y of t h e s t r u c t u r e a n d i n t o t h e l o a d b e a r i n g s t r a t u m as i l l u s t r a t e d in Fig. 6(a). In t h e c a s e of t h e M i n s t e r it w a s p r o p o s e d t h a t the p i l e s w o u l d b e e n d - b e a r i n g on the B u n t e r s a n d s t o n e. S u c h a t e c h n i q u e h a s t h e a d v a n t a g e of n o t d i s t u r b i n g the e x i s t i n g f o u n d a t i o n s a n d of b e i n g r e l a t i v e l y f r e e f r o m v i b r a t i o n (an i m p o r t a n t c o n s i d e r a t i o n in this c a s e s i n c e t h e f o u n d a t i o n s a p p e a r e d to b e so g r o s s l y o v e r loaded). H o w e v e r, t h e c a p a c i t y of a s i n g l e p i l e is o n l y a b o u t 45 t o n n e s a n d u p to 80 p i l e s w o u l d t h e r e f o r e be r e q u i r e d b e n e a t h e a c h p ier. T h e f a b r i c of t h e p i e r c o n s i s t s of a s h l a r f a c i n g e n c l o s i n g a r u b b l e a n d m o r t a r core, so that d e p i t e " s t i t c h i n g " the m a s o n r y w i t h r e i n f o r c e m e n t as s h o w n in F i g u r e 6 ( a ), it w a s c o n s i d e r e d that t h e i n s t a l l a t i o n of t h i s n u m b e r of p i l e s m i g h t s e r i o u s l y w e a k e n t h e p ier. T h e s c h e m e h a d Fig. 6 J U LJ Existing foundation being New reinforced concrete replaced' by PynfordStools base cast through stools through wtnch reinforcement Hand excavation of piles later threaded (I) (II) P r o p o s e d U n d e r p i n n i n g S c h e m e s (a) F o n d e d i l e - P a l i R a d i c e (b) P y n f o r d ' s S c h e m e 122
5 F o r a k y - G r o u n d F r e e z i n g : In o r d e r to a v o i d the p r o b l e m s of u n d e r p i n n i n g w o r k s t e n d i n g to c a u s e a b e a r i n g c a p a c i t y f a i l u r e, t h e t e c h n i q u e of g r o u n d f r e e z i n g w a s e x a m i n e d, as i l l u s t r a t e d in Fig. 7(a). A f t e r f r e e z i n g t h e g r o u n d, a s h a f t w a s t o b e e x c a v a t e d b e n e a t h e a c h p i e r to the t o p of t h e s a n d s t o n e a n d t h e n f i l l e d w i t h c o n c r e t e to f o r m a s i n g l e l a r g e p ile. T h i s s c h e m e w a s r e j e c t e d b e c a u s e of t h e u n s u i t a b i l i t y of t h e g r o u n d for f r e e z i n g, t h e u n k n o w n e f f e c t s of g r o u n d h e a v e on the r e m a i n d e r of t h e s t r u c t u r e a n d t h e u n a c c e p t a b l e r i s k of t h e s y s t e m m a l f u n c t i o n i n g. C e m e n t a t i o n P i l i n g : A n a l t e r n a t i v e p i l i n g s c h e m e is i l l u s t r a t e d in Fig. 7(b). In this, s h a f t s w o u l d be b o r e d to t h e t o p of t h e s a n d s t o n e on f o u r s i d e s of t h e p ier, a n d b e f i l l e d w i t h c o n c r e t e r e i n f o r c e d w i t h s t e e l H - p i l e s. To t r a n s f e r the load to t h e n e w piles, a p i l e cap w a s to be c o n s t r u c t e d, s t r e s s e d to t h e old f o u n d a t i o n s w i t h p r e s t r e s s i n g t e n d o n s. A d i s a d v a n t a g e of t h i s system is t h a t it r e l i e s e n t i r e l y on t h e o l d f o u n d a t i o n s to t r a n s f e r the lo a d f r o m t h e p i e r to the n e w p i l e cap. T h i s p r o p o s a l w a s s u b s e q u e n t l y a m e n d e d to p i l e s b e i n g m m d i a m e t e r s t e e l b a r s c o n c r e t e d i n t o the s a n d s t o n e a n d p r e - s t r e s s i n g t e n d o n s p a s s i n g d i r e c t l y b e n e a t h t h e pier. H o w e v e r, it w a s felt t h a t all p i l i n g s c h e m e s w o u l d t e n d to c r e a t e an u n d e s i r a b l e 'hard spot' b e n e a t h o n e p a r t o f the M i n s t e r, w h i c h c o u l d lead to d i s t r e s s e l s e w h e r e in t h e s t r u c t u r e in t h e e v e n t of g r o u n d s e t t l e m e n t. Frozen soil bridges over shaft temporarily Prestressing tendons Grouted t h r u s t line. T h i s w a s a c h i e v e d by s u p p o r t i n g e a c h of t h e f o u r C e n t r a l T o w e r p i e r s a n d t h e a d j a c e n t n a v e a n d t r a n s e p t c o l u m n s o n o n e f o o t i n g a b o u t m s q u a r e as s h o w n in Fig. 8 f or t h e N.W. pier. T h e m e t h o d c h o s e n w a s to e n c a s e t h e o l d N o r m a n f o o t i n g s in c o n c r e t e 2m thick, d r i l l h o r i z o n t a l h o l e s t h r o u g h t h e r e s u l t i n g c o m p o s i t e f o o t i n g, i n s e r t p r e s t r e s s i n g b a r s i n t o t h e s e d u c t s a n d s t r e s s t h e w h o l e t o g e t h e r. T h e b a d l y c r a c k e d r e m n a n t s of t h e c r o s s - w a l l s u p o n w h i c h t h e p i e r s w e r e c o n s t r u c t e d w e r e a l s o e n c a s e d in a r e i n f o r c e d c o n c r e t e c o l l a r (see Fig. 8). T h i s s e r v e d b o t h to s t r e n g t h e n t h e m a n d a l s o to p r o v i d e a b e t t e r s p r e a d o f l o a d f r o m t h e p i e r s i n t o t h e n e w f o u n d a t i o n s. D e t a i l s of t h e c o n s t r u c t i o n p r o c e d u r e a r e g i v e n in D o w r i c k (1970). T h e p r e s t r e s s i n g rods w e r e c o n c e n t r a t e d i n t o f o u r l a y e r s, w i t h t w o l a y e r s in e a c h o r t h o g o n a l d i r e c t i o n. B e c a u s e the s t r e n g t h e n i n g w o r k h a d to h a v e a life e x p e c t a n c y of h u n d r e d s of years, t h e r o d s w e r e m a d e of s t a i n l e s s steel, 3 2 m m d i a m e t e r. As the m a x i m u m l e n g t h of r o d that c o u l d b e r e a d i l y m a n u f a c t u r e d w a s 5.5m, p u r p o s e - m a d e s t a i n l e s s s t e e l c o u p l e r s w e r e u s e d to join t h e r ods. A t t h e i r ends, t h e r o d s w e r e a n c h o r e d w i t h a n u t a n d a n c h o r a g e p l a t e a f t e r s t r e s s i n g t o 35 t o n n e s. F u l l e r d e t a i l s of the p r e s t r e s s i n g a r e g i v e n in D o w r i c k (1970). T h e s c h e m e a d o p t e d h a s c e r t a i n s i m i l a r i t i e s w i t h t h e C e m e n t a t i o n s c h e m e d i s c u s s e d above, b u t w i t h the o m i s s i o n of t h e piles. H o w e v e r, the d i r e c t i o n s of p r e - s t r e s s i n g, (in N. E. - S. W. a n d N. W. - S. E. d i r e c t i o n s in Fig. 8), p r o v i d e d a b e t t e r f i n a l s t r u c t u r e, b u t i n v o l v e d t h e d i f f i c u l t t a s k of d r i l l i n g h o r i z o n t a l l y d i r e c t l y b e n e a t h e a c h p ier. T h e s u c c e s s of the u n d e r p i n n i n g s c h e m e d e p e n d e d on t h e a c c u r a c y o f the d r i l l i n g o p e r a t i o n. T h e d r i l l h o l e s v a r i e d in l e n g t h f r o m 6. 5 m to 1 5 m t h r o u g h 11th c e n t u r y m a s o n r y of d o u b t f u l q u a l i t y. T h e r e q u i r e d a c c u r a c y w a s d e t e r m i n e d by the v e r t i c a l s e p a r a t i o r o f t h e a l t e r n a t e l a y e r s of r o d s b e i n g o n l y 225mm. P r o b l e m s a r o s e b e c a u s e of t h e n o n - h o m o g e n e i t y of t h e m a s o n r y, w h i c h c o n s i s t e d of v a r i e d r u b b l e in w e a k m o r t a r, a n d t h e p r e s e n c e of a g r i d of l a r g e o a k b a u l k s u s e d b y t h e N o r m a n m a s o n s to r e i n f o r c e t h e i r f o o t i n g s. A f t e r m u c h (a) (b) F i g. 7 P r o p o s e d U n d e r p i n n i n g S c h e m e s (a) F o r a k y - G r o u n d F r e e z i n g (b) C e m e n t a t i o n P i l i n g UPPER CONCRETE COLLAR. U n d e r p i n n i n g D e s i g n A d o p t e d f o r the C e n t r a l T o w e r T o a v o i d t h e 'hard spot' i n h e r e n t in the o t h e r u n d e r p i n n i n g s c h e m e s, it w a s c o n s i d e r e d t h a t t h e n e w f o u n d a t i o n s s h o u l d be f o o t i n g s d e s i g n e d t o r e d u c e t h e s t r e s s i m p o s e d o n t h e u n d e r l y i n g c l a y t o a b o u t 290 k N / m 2 in o r d e r to m a k e the p r e s s u r e s s i m i l a r to t h o s e b e n e a t h t h e a d j o i n i n g N a v e, T r a n s e p t s a n d C h o i r. To a c h i e v e this, t h e e f f e c t i v e b e a r i n g a r e a b e n e a t h e a c h p i e r h a d to be d o u b l e d, b u t in s u c h a w a y t h a t the c e n t r e of a r e a c o i n c i d e d w i t h t h e c a l c u l a t e d F i g. 8 FKS8. N.W PIER FOUNDATIONS SHOWING NEW CONCRETE 4 EXISTING MASONRY P l a n a n d s e c t i o n o f N.W. p i e r f o u n d a t i o n s o f C e n t r a l T o w e r s h o w i n g n e w c o n c r e t e a n d e x i s t i n g m a s o n r y 123
6 e x p e r i m e n t a t i o n, r e a s o n a b l e a c c u r a c y w a s f i n a l l y a c h i e v e d u s i n g t w o t y p e s of d r i l l i n g e q u i p m e n t. T h e f i r s t w a s a d i a m o n d c o r i n g m a c h i n e w h i c h w a s b o t h s l o w a n d e x p e n s i v e b u t v e r y a c c u r a t e, and t h e s e c o n d w a s a r o t a r y p e r c u s s i v e d r i l l w i t h a 'down t h e hole' h a m m e r. T h e l a t t e r w a s e v e n t u a l l y e m p l o y e d, b e c a u s e it w a s b o t h f a s t e r and c h e a p e r. It w a s r e c o g n i s e d t h a t if t h e n e w c o n c r e t e f o u n d a t i o n s w e r e c a s t d i r e c t l y o n t o the clay t h e y w o u l d n o t c a r r y t h e i r s h a r e o f t h e load u n t i l f u r t h e r s e t t l e m e n t of t h e C e n t r a l T o w e r o c c u r r e d, s u f f i c i e n t to m o b i l i s e t h e s h e a r s t r e n g t h of t h e soil. As it w a s d e s i r a b l e to m i n i m i s e s e t t l e m e n t, a c o n c r e t e b a s e m m t h i c k a n d n o m i n a l l y r e i n f o r c e d, w a s c a s t b e n e a t h the n e w f o u n d a t i o n s (Fig. 8 b ). H y d r a u l i c flat jacks w e r e i n s e r t e d in the g a p b e t w e e n t h e n e w r a f t a n d c o n c r e t e b a s e (shown in p l a n in Fig. 9). A f t e r t h e p r e s t r e s s i n g of the m a i n f o u n d a t i o n s, t h e flat j a c k s w e r e i n f l a t e d u s i n g the e x i s t i n g s t r u c t u r e as a r e a c t i o n to t r a n s f e r p a r t o f the p i e r l o a d t o t h e n e w f o u n d a t i o n by p r e c o m p r e s s i n g t h e u n d e r l y i n g clay, as d i s c u s s e d below. The c o n c r e t e b a s e s w e r e all f o u n d e d o n t h e s t i f f s i l t y clay. T h e 8 m o f fill o b s e r v e d in b o r e h o l e 5 to t h e S.E. o f the N.W. p i e r (see Fig. 1) w a s a l o c a l i s e d a r e a n o t a f f e c t i n g t h e n e w f o u n d ations. W h e n m o v e m e n t of the c o n c r e t e b a s e s h a d c e a s e d u n d e r the a p p l i e d d e s i g n stress, the g a p b e t w e e n the b a s e a n d c o n c r e t e f o u n d a t i o n w a s p r e s s u r e - g r o u t e d u s i n g a g r o u t w i t h an e x p a n d i n g a d d i t i v e. P r e s s u r l s a t l o n of F l a t J a c k s P r e s s u r i s a t i o n of t h e h y d r a u l i c flat j a c k s w a s c a r r i e d o u t in s tages. I n i t i a l l y, a jack p r e s s u r e of 35 k g / c m 2 w a s applied, e q u i v a l e n t to a s t r e s s of 90 k N / m on t h e u n d e r s i d e of the c o n c r e t e bases. A s t h i s s t r e s s o n l y s l i g h t l y e x c e e d e d the p r e v i o u s o v e r b u r d e n p r e s s u r e of 75 k N / m 2, v e r y l i t t l e m o v e m e n t o c c u r r e d. There-, a f t e r t h e j a c k p r e s s u r e w a s i n c r e a s e d t o 70 kg/cm- ( e q u i v a l e n t to a s t r e s s of 170 k N / m b e n e a t h the f o u n d a t i o n s ) a n d in s m a l l e r i n c r e m e n t s to 105 k g / c m 2 ( e q u i v a l e n t to 2 50 k N / m 2 ). T h e p r e c o m p r e s s i o n of the c l a y w a s c l o s e l y m o n it o r e d. T h r e e b a s e s r o u g h l y t r i a n g u l a r in p l a n w e r e p r o v i d e d b e n e a t h e a c h p i e r (see Fig. 8(a)). A d j a c e n t to t h e t w o o u t e r c o r n e r s of e a c h b a s e (NI a n d N2 in Fig. 9), h o r i z o n t a l p r o t r u d i n g r o u n d b a r s h a d b e e n c a s t i n t o t h e b a s e a n d into t h e p r e s t r e s s e d c o n c r e t e f o u n d a t i o n s i m m e d i a t e l y above. By m e a s u r i n g t h e d i s t a n c e b e t w e e n e a c h p a i r of b a r s w i t h v e r n i e r c a l i p e r s, t h e m o v e m e n t of t h e b a s e r e l a t i v e to t h e c o n c r e t e f o u n d a t i o n c o u l d b e m e a s u r e d. O n the i n n e r c o r n e r a d j a c e n t to t h e p i e r (N7 in Fig. 9) a v e r t i c a l d u c t w a s c a s t in t h e c o n c r e t e f o u n d a t i o n t h r o u g h w h i c h p a s s e d a s t e e l r o d a n c h o r e d at its l o w e r e n d in the b a s e, t h u s p e r m i t t i n g s i m i l a r m e a s u r e m e n t s to b e m a d e. M o v e m e n t of t h e c o n c r e t e b a s e s r e l a t i v e to the p r e s t r e s s e d c o n c r e t e f o u n d a t i o n w a s m o n i t o r e d d a i l y d u r i n g jack p r e s s u r i s a t i o n - a t y p i c a l movement t i m e c u r v e is g i v e n in Fig. 10. E a c h s t r e s s i n c r e m e n t w a s m a i n t a i n e d u n t i l t h e r a t e of m o v e m e n t of t h e c o n c r e t e b a s e w a s less t h a n O. O l m m / d a y so t h a t the c o m p l e t e s t r e s s i n g o p e r a t i o n t o o k on a v e r a g e a b o u t 21 w e e k s. D u r i n g t h i s t i m e s e t t l e m e n t of the p i e r s and p r e s t r e s s e d c o n c r e t e f o u n d a t i o n s w a s m o n i t o r e d b y p r e c i s e l e v e l l i n g w i t h v e r y l i t t l e c h a n g e in l e v e l o b s e r v e d. A b o v e a soil c o n t a c t s t r e s s of 170 k N / m 2 it w a s n e c e s s a r y to u s e jack p r e s s u r e i n c r e m e n t s o f e.'jout 14 k g / c m 2 ( e q u i v a l e n t to a s oil s t r e s s of a b o u t 30 k N / m 2 ) in o r d e r to a v o i d o v e r s t r e s s i n g t h e clay. T h e m o v e m e n t o f the c o n c r e t e b a s e s b e n e a t h t h e N.W. a n d S.W. p i e r s are s h o w n in Fig. 9. It m a y b e s e e n t h a t the t h r e e c o r n e r s of e a c h c o n c r e t e b a s e s e t t l e d X 15 2 Indlcatea concrete base movement at 105kg /cm 2 jack pressure (appro*. 250kN/m? soil contact stress Hydraulic flatjack Fig. 9 P l a n of n e w N.W. a n d S.W. p i e r f o u n d a t i o n s of C e n t r a l T o w e r s h o w i n g f l a t jack l a y o u t a n d m o v e m e n t of c o n c r e t e b a s e s u n d e r a p p l i e d s t r e s s of k N / m 2 F i g. 10 M o v e m e n t of c o n c r e t e b a s e b e n e a t h S.W. S.W. q u a d r a n t o f N.W. p i e r w i t h t i m e as h y d r a u l i c flat j a c k p r e s s u r e i n c r e a s e d 124
7 F i g. 11 S E T T L E M E N T O F CONCRETE B A S E - m m RELATIVE TO PIERS A p p l i e d s t r e s s - r e l a t i v e s e t t l e m e n t b e h a v i o u r of c o n c r e t e b a s e s b e n e a t h C e n t r a l T o w e r p i e r s d i f f e r i n g a m o u n t s. T h e a p p l i e d s t r e s s - r e l a t i v e m o v e m e n t c u r v e s of t h e b a s e s a r e g i v e n in Fig. 11. In g e n e r a l the b a s e s s e t t l e d a b o u t 12 to 1 6 m m r e l a t i v e to the s t r u c t u r e a b o v e at a s t r e s s of k N / m 2, a l t h o u g h in c e r t a i n a r e a s (such as the N.W. q u a d r a n t of t h e S.W. pier) t h e s e t t l e m e n t s w e r e r e d u c e d by u n d e r l y i n g R o m a n f o u n d a t i o n s, w h i l e a r o u n d t h e N.W. p i e r t h e s e t t l e m e n t s w e r e o v e r 2 0 m m (see Fig. 9). On t h e b a s i s of cv = 1. 5 x m 2 / k N f r o m the c o n s o l i d a t i o n t e s t d a t a t h e a n t i c i p a t e d m o v e m e n t of t h e b a s e s for a s t r e s s i n c r e m e n t o f k N / m 2 a b o v e o v e r b u r d e n p r e s s u r e w o u l d h a v e b e e n a b o u t 30mm. W h e n r e l a t i v e m o v e m e n t of t h e n e w f o u n d a t i o n a n d c o n c r e t e b a s e e x c e e d e d 20 to 25mm, t h e r e w a s a t e n d e n c y for the h y d r a u l i c f l a t j a c k s to d e v e l o p leaks. In c a s e s w h e r e t h e l e a k i n g flat jack w a s t h e o u t e r m o s t in a g r o u p it w a s r e p l a c e d by a n e w j a c k w i t h m e t a l p l a t e s a b o v e a n d b e l o w to c o m p e n s a t e for the d i f f e r e n t i a l m o v e m e n t. S u c h l eaks l i m i t e d the s t r e s s e s w h i c h c o u l d b e a p p l i e d to t h e soil. In g e n e r a l, a f t e r c o m p l e t i o n of s t r e s s i n g the n e w f o u n d a t i o n s w e r e c a r r y i n g b e t w e e n 210 and k N / m 2 w i t h the r e s i d u e of the load b e i n g c a r r i e d b y the o l d f o u n d a t i o n s at a s t r e s s of b e t w e e n 310 a n d k N / m 2 B e h a v i o u r of t h e C e n t r a l T o w e r d u r i n g U n d e r p i n n i n g T i m e - s e t t l e m e n t c u r v e s f o r the f o u r C e n t r a l T o w e r p i e r s d u r i n g t h e c o u r s e of t h e u n d e r p i n n i n g w o r k a r e g i v e n in Fig. 12. In a d d i t i o n t h e s e t t l e m e n t of t h r e e p i e r s (L7, L0 & J 9 / H 9 - f or l o c a t i o n s e e Fig. 9) a d j a c e n t to the N.W. P i e r are g i v e n. D u r i n g t h e e n t i r e u n d e r p i n n i n g w o r k s f r o m 1968 to 1972 t h e N.W. a n d S.W. p i e r s b o t h s e t t l e d a b o u t 20mm, m a i n l y d u e to the r e m o v a l o f o v e r b u r d e n. T h e r a t e o f s e t t l e m e n t w a s a c c e l e r a t e d by i n c r e a s e s in t h e e x c a v a t i o n rate, b y c u t t i n g t h r o u g h t h e o l d N o r m a n f o o t i n g s (as i n d i c a t e d in Fig. 12) a n d a l s o to a l i m i t e d e x t e n t, b y t h e d r i l l i n g o p e r a t i o n s, p o s s i b l y as a r e s u l t of f l u s h w a t e r c a u s i n g a s l i g h t r i s e in the w a t e r table. In o r d e r to m i n i m i s e s e t t l e m e n t s d u e to r e m o v a l o f o v e r b u r d e n, t e m p o r a r y s a n d b a g g i n g of e x c a v a t e d a r e a s w a s u n d e r t a k e n. T h e r a t e of s e t t l e m e n t for t h e N.W. a n d S.W. p i e r s a v e r a g e d b e t w e e n 0. 2 a n d m m / 1 0 days w i t h o c c a s i o n a l p e a k s of to 1. 2 m m / 1 0 days. T h e w o r k on t h e N.E. a n d S.E. p i e r s w a s u n d e r t a k e r a f t e r the i n i t i a l w o r k on t h e t w o w e s t e r n p i e r s a n d as a r e s u l t of t h e e x p e r i e n c e g a i n e d, a f a s t e r r a t e of w o r k i n g w a s a d o p t e d w i t h less s a n d b a g g i n g e m p l o y e d. In c o n s e q u e n c e, t h e N.E. a n d S.E. p i e r s e x p e r i e n c e d a v e r a g e r a t e s of s e t t l e m e n t of to 0. 3 m m / 1 0 d a y s w i t h p e a k v a l u e s o f 0. 8 to 1. 4 m m / 1 0 days. T h e f i n a l s e t t l e m e n t of t h e s e t w o p i e r s w a s g r e a t e r t h a n t h e t w o w e s t e r n p i e r s b e i n g a b o u t 28 to 29mm. T h e e f f e c t s of o v e r b u r d e n r e m o v a l o n s e t t l e m e n t a r e d i s c u s s e d f u r t h e r in t h e s e c t i o n d e a l i n g w i t h t h e W e s t e r n T o w e r s. T h e d i f f e r e n t i a l s e t t l e m e n t b e t w e e n t h e N.W. P i e r (K9) a n d t h e a d j o i n i n g p i e r s K8 and J 9 / H 9 w a s 6 a n d 1 2 m m r e s p e c t i v e l y (see Fig. 12) a n d b e t w e e n K 8 a n d K 7 w a s a l s o 1 2 m m r e p r e s e n t i n g an a n g u l a r d i s t o r t i o n of a b o u t 1 in 700. T h i s d i f f e r e n t i a l s e t t l e m e n t i n d u c e d f u r t h e r m o v e m e n t a l o n g o l d c r a c k s. T h e s e t t l e m e n t r e c o r d s a l s o d e m o n s t r a t e t h e abilit o f t h e N o r m a n f o o t i n g s to t r a n s m i t s h e a r f o r c e s d e s p i t e b e i n g s e v e r e l y c r a c k e d. B e n e a t h t h e N.W. p i e r t h e r e w a s a d i a g o n a l s h e a r c r a c k in t h e m a s o n r y b e t w e e n it a n d p i e r K8 i m m e d i a t e l y to t h e w e s t (see Fig. 9) a n d t h i s w a s a s s u m e d to d e l i n e a t e the e f f e c t i v e l o a d b e a r i n g a r e a of the p i e r as d i s c u s s e d e a r l i e r. H o w e v e r, w h e n the N o r m a n f o o t i n g b e t w e e n p i e r s K7 a n d K8 (see Fig. 9) w a s s e v e r e d, t h e r a t e of s e t t l e m e n t of the N.W. p i e r s u d d e n l y i n c r e a s e d (see i n c i d e n t 2 in F i g. 12). 1 - Excavating & casting concrete bases to NWS NE of NW Pier 2 -Cutting through Norman footing between K7&K8 I For location 3 -Cutting through Norman footing between L7&L8 I.. 4 -Drilling beneath NW Pier started seengurey 5 - Extra sandbagging in Nave 6 - Excavating & cast ing concrete base to SW of SW Pier 7 - Excavating & casting concrete base to SE of SW Pier 8 - DriSng beneath SW Pier started 9 - Cutting through Norman raft between NW&NE Piers 10 Cutting through Norman footing between H9 & F Rat jacks beneath NW& SW Piers inflated to 70kg/cm2 12-R at jacks beneath NW&SWPiers inflated to 105 kg/cm2 F i g. 12 S e t t l e m e n t of C e n t r a l T o w e r p i e r s d u r i n g u n d e r p i n n i n g 125
8 U N D E R P I N N I N G O F T H E W E S T E R N T O W E R S E a c h of t h e t w o W e s t e r n T o w e r s w e i g h s a b o u t 1 0, t o n n e s a n d is p a r t i a l l y c o n s t r u c t e d on the r e m n a n t f o u n d a t i o n s of a p a i r of late 12th c e n t u r y t o w e r s w h i c h w e r e b u i l t j u s t o u t s i d e t h e w e s t e n d o f the N o r m a n C h u r c h (see Fig. 1). H e n c e the p r e s e n t f o u n d a t i o n s a r e a m i x t u r e of 12th and 15th c e n t u r y w o r k of v e r y v a r i a b l e q u a l i t y w i t h s o m e 11th c e n t u r y m a s o n r y s u p p o r t i n g t h e i n t e r i o r p i e r t o e a c h tower. It w a s c a l c u l a t e d t h a t the a v e r a g e b e a r i n g p r e s s u r e b e n e a t h t h e s e f o u n d a t i o n s w a s a b o u t 515 k N / m 2 w h i c h a l t h o u g h n o t as h i g h as b e n e a t h t h e C e n t r a l Tower, w a s h i g h e r t h a n w o u l d be p e r m i t t e d to a v o i d o v e r s t r e s s i n g the clay. A s t h e t o w e r s h a d s e t t l e d up to 7 5 m m w i t h r e s p e c t to the N a v e a n d w e r e l e a n i n g o u t w a r d s m m at T r i f o r i u m level, it w a s d e c i d e d to e n l a r g e the f o u n d a t i o n s so as t o m a k e t h e b e a r i n g p r e s s u r e s b e n e a t h t h e W e s t e r n T o w e r s s i m i l a r to t h o s e for the r e s t of t h e M i n s t e r. T h i s w a s a c h i e v e d by f o u n d i n g e a c h t o w e r on a r a f t 2 0 m s q u a r e in plan, to be c o n s t r u c t e d in a m a n n e r s i m i l a r t o that a l r e a d y d e s c r i b e d f o r the i n d i v i d u a l p i e r s of the C e n t r a l T o w e r t o g i v e an a v e r a g e b e a r i n g p r e s s u r e of k N / m 2 (see Fig. 13(a)). The p r e s t r e s s i n g b a r s w e r e a r r a n g e d in a N-S, E - W p a t t e r n w h i c h r e d u c e d t h e m a x i m u m l e n g t h of d r i l l i n g to 5m t h r o u g h the b u t t r e s s e s. O n t h e b a s i s of e x p e r i e n c e w i t h e x c a v a t i o n a r o u n d t h e N.E. a n d S.E. p i e r s of t h e C e n t r a l T o w e r w h e r e s e t t l e m e n t s i n d u c e d b y o v e r b u r d e n r e m o v a l w e r e a c c e p t a b l e, t e m p o r a r y s a n d b a g g i n g a f t e r e x p o s u r e o f t h e f o u n d a t i o n s w a s a g a i n o m i t t e d for the s a k e of speed, a n d r a p i d N» m ) e x c a v a t i o n t e c h n i q u e s w e r e a d o p t e d. D e t a i l s of t h e s e are g i v e n by C o r b e t t (1972). It w a s f u r t h e r a r g u e d t h a t as t h e b e a r i n g p r e s s u r e s for the W e s t e r n T o w e r s w e r e l o w e r t h a n t h o s e b e n e a t h t h e p i e r s of t h e C e n t r a l T o w e r i n d u c e d s e t t l e m e n t s w o u l d be less. A f t e r e x c a v a t i o n h a d b e e n in p r o g r e s s f o r some time, t h e m e a s u r e d s e t t l e m e n t s of t h e t o w e r s, p r e v i o u s l y s l i g h t, b e g a n to i n c r e a s e rapidly. C o n c e r n w a s e x p r e s s e d w h e n t h e s e t t l e m e n t r a t e s i n i t i a l l y e x c e e d e d 1. 0 m m / 1 0 d a y s f o r m o r e t h a n 30 d a y s (see Fig. 14(a)) w i t h s u b s t a n t i a l e x c a v a t i o n s t i l l to be u n d e r t a k e n. (In e x c a v a t i n g for the C e n t r a l T o w e r p i e r f o u n d a t i o n s s e t t l e m e n t s h a d o c c a s i o n a l l y r e a c h e d or e x c e e d e d 1. 0 m m / 1 0 d a y s b u t o n l y f o r s h o r t p e r i o d s of less t h a n 30 d a y s - a m o r e n o r m a l r a t e w a s 0. 3 m m / 10 d a y s ). S t e e l s h o r e s w e r e e r e c t e d to g i v e l a t e r a l r e s t r a i n t to t h e t o w e r s a n d a s t r i c t s e q u e n c e o f e x c a v a t i o n w a s i n s t i g a t e d w h e n it w a s r e a l i s e d t h a t the d e p t h of t h e e x c a v a t i o n h a d a p r o f o u n d e f f e c t on t h e s e t t l e m e n t rate. F o r e x a m p l e b u t t r e s s M2 is s u r r o u n d e d b y f o u r a r e a s o f e x c a v a t i o n (see Fig. 13(b)). W h e n a r e a 1 w a s e x c a v a t e d to f o r m a t i o n level, t h e s e t t l e m e n t r a t e of M 2 i n c r e a s e d at p o i n t A (see Fig. 14). T h e s e t t l e m e n t r a t e o n l y d e c r e a s e d w h e n the c o n c r e t e s l a b w a s c a s t a n d s a n d b a g s p l a c e d (point B ). T h e s e t t l e m e n t r a t e i n c r e a s e d a g a i n w h e n a r e a 4 w a s e x c a v a t e d (point C) c l o s e l y f o l l o w e d b y a r e a 5. T h e s e t t l e m e n t r a t e d e c r e a s e d w h e n b o t h a r e a s w e r e c o n c r e t e d (point D) o n l y to i n c r e a s e a g a i n w h e n a r e a 3 w a s e x c a v a t e d (point E ). T h e r e s u l t s f r o m all a r e a s b e n e a t h t h e W e s t e r n T o w e r s h a v e b e e n c o m b i n e d in Fig. 15 a n d d e m o n s t r a t e t h a t o v e r the b o t t o m lm of e x c a v a t i o n t h e s e t t l e m e n t r a t e s i n c r e a s e d r a m a t i c a l l y f r o m 0. 5 m m / 1 0 d a y s t o 3. 0 m / 1 0 days. O n t h e b a s i s of t h i s data, e x c a v a t i o n a d j a c e n t to a n y s t r u c t u r a l e l e m e n t w a s r e s t r i c t e d to one a r e a at a t i m e o v e r t h e l o w e r m of d i g w i t h t h e w o r k to b e c a r r i e d o u t as q u i c k l y as p o s s i b l e. T h e c o n c r e t e b a s e w a s t o be c a s t i m m e d i a t e l y a n d s u r c h a r g e d w i t h s a n d b a g s lm h i g h b e f o r e t h e n e x t F i g. 13 H H Outline of new foundations Prestressing bars W e s t e r n T o w e r s (a) P l a n of N e w F o u n d a t i o n s (b) E x c a v a t i o n A r e a s s h o w i n g l e v e l l i n g p o i n t s F i g. 14 S e t t l e m e n t o f S.W. T o w e r d u r i n g u n d e r p i n n i n g s h o w i n g e f f e c t of e x c a v a t i o n d e p t h 126
9 F i g. 15 E f f e c t of e x c a v a t i o n d e p t h on s e t t l e m e n t r a t e of W e s t e r n T o w e r s a r e a c o u l d b e e x c a v a t e d. S e t t l e m e n t s w e r e s a t i s f a c t o r i l y c o n t r o l l e d in this w a y u n t i l the m a i n r a f t w a s cast. F r o m t h e s t a r t of t h e u n d e r p i n n i n g in M a r c h 1970 to its c o m p l e t i o n in O c t o b e r 1972 t h e t w o t o w e r s e a c h s e t t l e d a b o u t 3 0 m m w i t h a s l i g h t t e n d e n c y to t i l t i n w a r d s as f o l l o w s : F i g. 16 M o v e m e n t of c o n c r e t e b a s e s b e n e a t h W e s t e r n T o w e r s u n d e r a p p l i e d s t r e s s of 250 k N / m 2 N. W T o w e r Jl: 29 7mm J2: 29 7mm J3: 7. 0 m m J4: 2. 8 m m Kl: 33 1mm K2 : 34 9mm N a v e ( _ LI: mm L2: m m L3: m m L 4 : 2. 7mm Ml: m m M2: mm M3: 7. 9 m m M 4 : 2. 3mm S. W T o w e r S.W. T o w e r w h e r e a l a r g e s o f t p o c k e t h a d b e e n e n c o u n t e r e d d u r i n g e x c a v a t i o n for the c o n c r e t e bases. As a r e s u l t of t h e jacking, t h e f o u n d a t i o n s to t h e S.W. T o w e r m o v e d u p w a r d s a b o u t 1 to lijmm (see Fig. 14). O n e of the m o r e d i f f i c u l t t a s k s to u n d e r p i n n i n g t h e W e s t e r n T o w e r s w a s g r o u t i n g up t h e g a p b e t w e e n t h e c o n c r e t e b a s e a n d r a f t on a c c o u n t of t h e l arge a r e a s i n v o l v e d. O u t s i d e a b o u t 3200 l i t r e s of g r o u t h a d t o be p u m p e d b e n e a t h e a c h t o w e r and i n s i d e a b o u t litres. (The l o c a t i o n of t h e l e v e l l i n g p o i n t s is g i v e n in F i g u r e 13(b) a n d t h e s e t t l e m e n t - t i m e b e h a v i o u r of LI, L 2, Ml a n d M2 in F i g u r e 14). T h e h y d r a u l i c f l a t j a c k s b e n e a t h e a c h t o w e r w e r e l i n k e d i n t o t w o c i r c u i t s - o n e i n s i d e a n d one o u t s i d e. O n the b a s i s o f e x p e r i e n c e of the C e n t r a l T o w e r t h e flat j a c k s w e r e p r e s s u r i s e d i n i t i a l l y to g i v e a s o i l c o n t a c t s t r e s s b e n e a t h the c o n c r e t e b a s e s of 100 k N / m 2. T h e r e a f t e r s t r e s s i n c r e a s e s of 3 3 k N / m 2 w e r e a p p l i e d u p to 200 k N / m 2, e a c h i n c r e m e n t b e i n g h e l d for a b o u t o n e m o n t h. F r o m k N / m 2 s t r e s s i n c r e m e n t s of a b o u t 17 k N / m 2 w e r e used, e a c h i n c r e m e n t b e i n g h e l d for t w o to t h r e e m o n t h s. T h e m o v e m e n t s of t h e c o n c r e t e b a s e s b e n e a t h e a c h t o w e r w e r e m e a s u r e d at five p o i n t s i n s i d e a n d ten p o i n t s o u t s i d e. T h e m o v e m e n t s of t h e c o n c r e t e b a s e s a r e g i v e n in Fig. 16. T h e a p p l i e d s t r e s s - s e t t l e m e n t b e h a v i o u r of t h e c o n c r e t e b a s e s b e n e a t h the S.W. T o w e r is g i v e n in Fig. 17. I n s i d e the m e a s u r e d m o v e m e n t s of t h e c o n c r e t e b a s e u n d e r 250 k N / m 2 w e r e a b o u t 1 3 m m a n d c o r r e s p o n d e d c l o s e l y w i t h t h e l o w e r b o u n d m e a s u r e m e n t s of m o v e m e n t b e n e a t h t h e C e n t r a l T o w e r c o n c r e t e bases. O u t s i d e the m o v e m e n t w a s m u c h m o r e v a r i a b l e, a v e r a g i n g a b o u t 17 to 1 8 m m ( c o r r e s p o n d i n g to the u p p e r b o u n d m o v e m e n t s f r o m t h e C e n t r a l T o w e r ), w i t h 4 2 m m o c c u r r i n g in t h e S.W. c o r n e r o f the <o F i g. 17 Settlements inside S.W. TOWER Settlements outside Overburden stress r n _ Results from ' ' Central Tower SETTLEMENT OF CONCRETE BASE - mm A p p l i e d s t r e s s - r e l a t i v e s e t t l e m e n t b e h a v i o u r of c o n c r e t e b a s e s b e n e a t h S o u t h - W e s t T o w e r 127
10 F i g. 18 T h e E a s t W a l l s u p p o r t e d b y s t e e l s h o r e s d u r i n g u n d e r p i n n i n g ( C o u r t e s y S h e p h e r d B u i l d i n g G r o u p Ltd.) E A S T W A L L U N D E R P I N N I N G At t h e s a m e t i m e as t h e w o r k on the C e n t r a l T o w e r w a s p r o c e e d i n g, the E a s t W a l l of the M i n s t e r w a s u n d e r p i n n e d. T h e s o u t h e r n b u t t r e s s h a d b e e n f o u n d to be o v e r m m o u t of p l u m b in a h e i g h t of 24m. V e r t i c a l c r a c k s in the e a s t e r n - m o s t b a y of the C h o i r ( b e t w e e n M 1 8 a n d M 1 9 in Fig. 1) i n d i c a t e d o u t w a r d r o t a t i o n of the w a l l w i t h 1 0 m m of m o v e m e n t h a v i n g t a k e n p l a c e s i n c e r e p a i r s w e r e u n d e r t a k e n at T r i f o r i u m l e v e l in A t roof level, 2 0 m m of m o v e m e n t of the lead f l a s h i n g s i n c e 1940 c o n f i r m e d the r o t a t i o n t h e o r y. T h e c o n d i t i o n of the E a s t W a l l w a s a g g r a v a t e d by the f r a g i l i t y of the G r e a t E a s t W i n d o w. T h i s w i n d o w, c o n s t r u c t e d in , is o n e of the b i g g e s t e x p a n s e s of s t a i n e d g l a s s in t h e w o r l d, m e a s u r i n g 23m h i g h by 10m w i d e (see Fig. 18). Not o n l y w a s it o u t of p l u m b, b u t it a l s o b o w e d o u t w a r d s m m in p l a n at m i d - h e i g h t. T h e r e was, f u r t h e r m o r e, a t e n d e n c y for t h e w i n d o w to s p l i t d o w n t h e m i d d l e b e c a u s e t h e w h o l e o f the Ea s t W a l l w a s h o g g i n g as s h o w n by the l e v e l s of the w e a t h e r i n g c o u r s e at g r o u n d level, a n d by a v e r t i c a l c r a c k on t h e line of s y m m e t r y b e l o w t h e w i n d o w. As n o t h i n g w a s k n o w n a b o u t t h e f o u n d a t i o n s, a s m a l l e x p l o r a t o r y d i g w a s c a r r i e d o u t a d j a c e n t to o n e of the m a i n b u t t r e s s e s. It a p p e a r e d t h a t the b u t t r e s s h a d b e e n a d d e d a f t e r c o n s t r u c t i o n of the w a l l h a d c o m m e n c e d, for t h e r e w a s n o b o n d i n g b e t w e e n the t w o u n t i l a b o v e g r o u n d level. N e i t h e r w a l l n o r b u t t r e s s b r o a d e n e d o u t b e l o w g r o u n d l evel to a n y f o r m of f o o t i n g - if a n y t h i n g t h e i r c o n d i t i o n t e n d e d to d e t e r i o r a t e w i t h depth, t h e l o w e r 1. 8 m of " f o u n d a t i o n " c o n s i s t i n g of u n d r e s s e d s t o n e s r o u g h l y l a i d in a t r e n c h w i t h no m o r t a r for b o n d i n g. A g r a p h i c a l t h r u s t line a n a l y s i s i n d i c a t e d a t h r u s t of a b o u t t o n n e s in e a c h of t h e b u t t r e s s e s f l a n k i n g the G r e a t E a s t W i n d o w. T h e line of t h r u s t w a s v e r y c l o s e to the o u t e r f a c e of the w a l l (see Fig. 19). F u r t h e r m o r e, t h e r e w a s a f u r t h e r t h r u s t of a b o u t t o n n e s in t h e b u t t r e s s e d t u r r e t s t a i r c a s e at e a c h e n d of t h e E a s t W a l l. T h e a r e a l e x t e n t of the f o u n d a t i o n c a r r y i n g t h e s e l o a d s w a s F i g. 19 E l e v a t i o n a n d h a l f - p l a n of E a s t W a l l s h o w i n g l o a d s a n d l o c a t i o n of s e t t l e m e n t m e a s u r i n g p o i n t s a s s e s s e d t o b e b o u n d e d b y Y - Y a n d Z-Z in Fig t h e c e n t r e l i n e s of e a s t e r n m o s t C h o i r A i s l e w i n d o w a n d t h e G r e a t E a s t W i n d o w r e s p e c t i v e l y, b e n e a t h b o t h of w h i c h t h e m a s o n r y w a s b a d l y c r a c k e d. By a p r o c e s s of t r i a l a n d e r r o r the f o u n d a t i o n w a s s u b d i v i d e d a l o n g X - X so t h a t the c e n t r o i d of e a c h a r e a c o i n c i d e d m o s t c l o s e l y w i t h t h e t h r u s t line. D e s p i t e t h i s the 1400 t o n n e t h r u s t line w a s s t i l l f o u n d to b e e c c e n t r i c to the c e n t r e of a r e a C s h o w n in Fig. 19. T h i s w o u l d c a u s e b o t h o u t w a r d r o t a t i o n of the b u t t r e s s a n d h o g g i n g a b o u t Z-Z as t h e l e v e l l i n g m e a s u r e m e n t s i n d i c a t e d. M o d i f y i n g the e c c e n t r i c a l l y l o a d e d a r e a as s u g g e s t e d b y B r i n c h H a n s e n (1961) g a v e an a v e r a g e b e a r i n g p r e s s u r e of 570 k N / m. T h e a v e r a g e b e a r i n g p r e s s u r e b e n e a t h the b u t t r e s s e d t u r r e t s t a i r c a s e w a s s i m i l a r. In b o t h a r e a s the f a c t o r of s a f e t y a g a i n s t s h e a r f a i l u r e w a s o n l y a b o u t 1.4. A l t h o u g h the s h e a r s t r e n g t h of t h e c l a y m a y h a v e b e e n u n d e r e s t i m a t e d, t h e l o w f a c t o r of s a f e t y w a s c o n s i d e r e d m o r e s e r i o u s t h a n for t h e C e n t r a l T o w e r o n a c c o u n t of the a b s e n c e of s u p p o r t f r o m any o t h e r p a r t of the s t r u c t u r e. T h e h i g h s h e a r s t r e s s e s in t h e soil b e n e a t h t h e b u t t r e s s r e s u l t e d in c r e e p a n d p r o g r e s s i v e o u t w a r d r o t a t i o n of t h e w a l l. T o p r e v e n t t h e E a s t W a l l f r o m e v e n t u a l l y f a l l i n g o u t w a r d s, it w a s n e c e s s a r y to p r o v i d e a s u b s t a n t i a l toe to t h e e x i s t i n g f o o t i n g s. B e f o r e u n d e r p i n n i n g c o m m e n c e d, t e m p o r a r y s h o r e s w e r e e r e c t e d to r e s i s t o u t w a r d m o v e m e n t (see Fig. 18). T h e 128
11 s h o r e s w e r e s t e e l t r u s s e s f o u n d e d o n s i m p l e s p r e a d f o o t i n g s b u t i n c o r p o r a t i n g at the b a s e a p a i r o f f l a t j a c k s in t a n d e m c o n n e c t e d to a c o n s t a n t p r e s s u r e d e v i c e, so t h a t t e m p e r a t u r e m o v e m e n t s as w e l l as a n y i n d u c e d v e r t i c a l s e t t l e m e n t c o u l d b e a c c o m m o d a t e d w i t h o u t o v e r loading. T h e u n d e r p i n n i n g m e t h o d w a s the c l a s s i c a l o n e of d r i v i n g 1. 2 m w i d e h e a d i n g s, to r e p l a c e the e x i s t i n g f o u n d a t i o n w i t h a c o m p l e t e n e w o n e of t w i c e t h e w i d t h. W i t h t h e n e w f o o t i n g w i d t h of 5.5m, t h e a v e r a g e b e a r i n g p r e s s u r e w a s r e d u c e d to 250 k N / m 2. T h e c e n t r e o f t h r u s t f r o m the s u p e r s t r u c t u r e w a s a r r a n g e d to b e w i t h i n t h e i n n e r h a l f o f t h e f o o t i n g so t hat the w a l l w o u l d b e c o n s t r a i n e d to r o t a t e i n w a r d s. T h e u n d e r p i n n i n g to t h e E a s t W a l l w a s c a r r i e d r o u n d b e n e a t h the e a s t e r n m o s t b a y of t h e N o r t h a n d S o u t h C h o i r A i s l e s (between J 1 8 & J 1 9 and M 1 8 & M 1 9 in Fig. 1) a n d t h e w h o l e l e n g t h w a s d i v i d e d into f o u r zones. T o c a u s e the l e a s t p o s s i b l e d i s t u r b a n c e to t h e f a bric, the s e q u e n c e o f w o r k i n g a l l o w e d for o n l y o n e h e a d i n g in e a c h z one t o be o p e n at a n y t i m e and for t h e s e h e a d i n g s to be w e l l s e p a r a t e d in plan. F u r t h e r m o r e, e a c h s e c t i o n of t h e f o o t i n g w a s c o n c r e t e d as s o o n as p o s s i b l e a f t e r c o m p l e t i o n of the e x c a v a t i o n of the h e a d i n g. D u r i n g t h e site i n v e s t i g a t i o n t h e p r e s e n c e of a lm t h i c k b a n d of l a m i n a t e d c l a y b e n e a t h t h e f i r m s i l t y clay h a d n o t b e e n c l e a r l y r e c o g n i s e d l a r g e l y on a c c o u n t of the r o t a r y c o r i n g t e c h n i q u e d i s t u r b i n g t h e soil f a bric. W h e n e a c h h e a d i n g w a s e x c a v a t e d, t h e l a m i n a t e d c l a y q u i c k l y s w e l l e d on the r e m o v a l of load a n d r e - c o n s o l i d - ated as the e x c a v a t i o n of a d j a c e n t h e a d i n g s c a u s e d load to be t r a n s f e r r e d to t h e n e w f o u n d a t i o n s. A s a r e s u l t, t h e w a l l s e t t l e d m o r e t h a n a n t i c i p a t e d w h i l e t h e u n d e r p i n n i n g w a s ex ecuted. S e t t l e m e n t m e a s u r e m e n t s w e r e t a k e n at s i x l o c a t i o n s o n t h e E a s t W a l l a n d t w o o n e a c h o f t h e N o r t h a n d S o u t h C h o i r A i s l e s. (See Fig. 19 f o r l o c a t i o n s o n t h e s o u t h e r n h a l f of the w a l l ). T h e s e t t l e m e n t r e c o r d s f o r f i v e l o c a t i o n s are g i v e n in Fig. 20 a n d t h e s e t t l e m e n t c o n t o u r s a c r o s s the E a s t W a l l at 4 - w e e k l y i n t e r v a l s in Fig. 21. T o m i n i m i s e a g g r a v a t i n g t h e h o g g i n g c o n d i t i o n of t h e w a l l t h e b u t t r e s s e s at the c o r n e r s w e r e f i r s t u n d e r p i n n e d, f o l l o w e d b y t h e b u t t r e s s e s f l a n k i n g t h e e a s t w i n d o w (after w e e k 8 in Fig. 21). T h e r e a f t e r, e x c a v a t i o n of the h e a d i n g s p r o g r e s s e d t o w a r d s t h e c e n t r e of the G r e a t E a s t W i n d o w c a u s i n g s l i g h t s a g g i n g. T h e m a x i m u m a n g u l a r d i s t o r t i o n a c r o s s t h e b u t t r e s s e s F i g. 21 C o n t o u r s of s e t t l e m e n t of E a s t W a l l at 4 - w e e k i n t e r v a l s d u r i n g u n d e r p i n n i n g f l a n k i n g t h e C h o i r A i s l e w i n d o w s in t h e E a s t W a l l (3 a n d 4 in Fig. 19) w a s a b o u t 1 in w h e r e a s b e n e a t h t h e E a s t W i n d o w b e t w e e n p o i n t s 4 a n d 5 (the c e n t r e line of t h e w i n d o w, b e n e a t h w h i c h t h e r e w a s an e x i s t i n g l a r g e crack) it w a s 1 in 1500 to 1 in D u r i n g the u n d e r p i n n i n g the g l a s s in the G r e a t E a s t W i n d o w w a s f r e e d at t h e e d g e s to a v o i d c r a c k i n g as t h e s e t t l e m e n t o c c u r r e d. T h e i n c l u s i o n of f l a t j a c k s b e t w e e n t h e s u p e r s t r u c t u r e a n d t h e n e w f o o t i n g s w a s c o n s i d e r e d i n i t i a l l y in o r d e r t o c o u n t e r t h e e f f e c t s of s e t t l e m e n t s d u r i n g the w o r k s. H o w e v e r, it w a s f e l t t h a t t h e s h e a r k e y s, p r o v i d e d b e t w e e n a d j a c e n t e l e m e n t s of t h e f o o t i n g, w o u l d p r e v e n t e a c h e l e m e n t b e i n g l o a d e d i n d e p e n d e n t of t h e o t h e r s to i n d u c e r e - c o n s o l i d a t i o n o f t h e l a m i n a t e d clay. W h e n t h e f l a t j a c k s s t r e s s i n g t h e s t e e l s h o r e s w e r e d e p r e s s u r i s e d in s t a g e s, f u r t h e r s e t t l e m e n t of t h e w a l l o c c u r r e d as i n d i c a t e d in Fig. 20. S e t t l e m e n t v i r t u a l l y c e a s e d in A s the s e t t l e m e n t s h a d b e e n m e a s u r e d r e l a t i v e t o a s h a l l o w t e m p o r a r y b e n c h m a r k o u t s i d e t h e E a s t Wall, s e t t l e m e n t m e a s u r e m e n t s a f t e r t h i s d a t e w e r e n o l o n g e r c o n s i d e r e d s u f f i c i e n t l y r e l i a b l e. C O N C L U D I N G R E M A R K S 1. T h e a r c h a e o l o g i c a l s t u d i e s c a r r i e d o u t d u r i n g t h e c o u r s e of t h e u n d e r p i n n i n g, a l t h o u g h not d i s c u s s e d in d e t a i l in this p a p e r, h a d a p r o f o u n d i n f l u e n c e on t h e u n d e r s t a n d i n g of the b e h a v i o u r of t h e f a b r i c a n d the f o u n d a t i o n s b o t h in the p a s t a n d d u r i n g the u n d e r p i n n i n g. F i g. 20 S e t t l e m e n t o f s o u t h e r n h a l f of E a s t W a l l d u r i n g u n d e r p i n n i n g 2. T h e i n f l u e n c e of p r e v i o u s b u i l d e r s h a s h a d a s i g n i f i c a n t e f f e c t o n t h e w o r k. - T h e d i s c o v e r y of t h e r e m n a n t s of t h e R o m a n l e g i o n h e a d q u a r t e r s b e n e a t h the M i n s t e r p r o m p t e d the c r e a t i o n of a p e r m a n e n t u n d e r c r o f t m u s e u m b e n e a t h the C e n t r a l T o w e r w h e r e t h e r e m a i n s t o g e t h e r w i t h t h e N o r m a n f o u n d a t i o n s, the u n d e r p i n n i n g w o r k s a n d a h i s t o r y of t h e M i n s t e r c o u l d b e vi e w e d. - T h e m a s s i v e n e s s of the f o u n d a t i o n s to the N o r m a n C h u r c h c l e a r l y i n d i c a t e d t h e N o r m a n s ' a w a r e n e s s of g o o d f o u n d a t i o n s
12 - T h e "art" of f o u n d a t i o n d e s i g n a p p e a r s to h a v e b e e n lost by t h e M i d d l e A g e s to j u d g e f r o m t h e i n a d e q u a t e f o u n d a t i o n s, b o t h in c o n c e p t a n d e x e c u t i o n, b e n e a t h t h e East W all. T h i s w o u l d a p p e a r at v a r i a n c e w i t h e x p e r i e n c e in F r a n c e r e p o r t e d b y K e r i s e l (1975). - T h e c o n s t r u c t i o n of the h e a v y G o t h i c C e n t r a l T o w e r r e l i e d e n t i r e l y on t h e size a n d i n t e g r i t y of t h e N o r m a n f o u n d a t i o n s w i t h l i t t l e a w a r e n e s s of the u n d e r l y i n g so i l strata. - T h e d r a i n s i n s t a l l e d b y the R o m a n s still c o n t i n u e to i n f l u e n c e t h e p e r c h e d w a t e r t a b l e in Y o r k, as d e m o n s t r a t e d b y r e c e n t b u i l d i n g w o r k w h i c h s e v e r e d such a d r a i n and led to a r i s e in t h e w a t e r t a b l e at times o f h e a v y rain. 3. A n a l y s i s of t h e f o u n d a t i o n s of o l d s t r u c t u r e s such as t h e M i n s t e r is d i f f i c u l t on a c c o u n t of t h e u n k n o w n e f f e c t s of t h e i n t e r a c t i o n of t h e f o u n d a t i o n s. T h e i n f l u e n c e of o v e r b u r d e n r e m o v a l has b e e n f o u n d to be v e r y s i g n i f i c a n t in r e l a t i o n to s e t t l e m e n t. 4. A n a t t e m p t to r e c o n s t r u c t the s e q u e n c e of s e t t l e m e n t s of the M i n s t e r s i n c e 1080, f r o m e s t i m a t e d l o a d i n g s a n d the m e a s u r e d c o n s o l i d a t i o n p r o p e r t i e s of t h e clay, p r o d u c e d d i f f e r e n t i a l s e t t l e m e n t s w h i c h c o r r e s p o n d r e m a r k a b l y w e l l w i t h the o b s e r v e d d i f f e r e n c e s in level. S i m i l a r a g r e e m e n t b e t w e e n e s t i m a t e d a n d o b s e r v e d s e t t l e m e n t s w a s a l s o f o u n d by t h e a u t h o r (1974) in his a n a l y s i s of St. P a u l ' s C a t h e d r a l in L o ndon, d e s p i t e s i m p l e a p p r o x i m a t i o n of t h e s t r u c t u r a l l o a d i n g s a n d soil p a r a m e t e r s. 5. D u r i n g the c o u r s e o f t h e u n d e r p i n n i n g w o r k the m a j o r e l e m e n t s of the M i n s t e r - the C e n t r a l Tower, t h e W e s t e r n T o w e r s, a n d the E a s t W a l l - s e t t l e d b e t w e e n 20 a n d 30mm. D e s p i t e s u c h s e t t l e m e n t s t h e i n t e g r i t y of the s t r u c t u r e w a s r e t a i n e d w i t h m o v e m e n t o n l y o c c u r r i n g a l o n g e x i s t i n g c r acks. 6. T h e f o r m of u n d e r p i n n i n g a d o p t e d w o u l d a p p e a r to h a v e b e e n s u c c e s s f u l, for in t h e five y e a r s f r o m O c t o b e r 1972 to A p r i l 1977 f o l l o w i n g c o m p l e t i o n of the u n d e r p i n n i n g, p r e c i s e l e v e l l i n g m e a s u r e m e n t s i n d i c a t e d a u n i f o r m s e t t l e m e n t of the M i n s t e r of b e t w e e n 0. 7 a n d 1.5mm. T h e m a j o r i t y of this m o v e m e n t o c c u r r e d d u r i n g the d r o u g h t of A s t h e l e v e l l i n g w a s c o n s i d e r e d to be only a c c u r a t e to w i t h i n 0.3mm, p e r m a n e n t l e v e l l i n g s o c k e t s of t h e t y p e d e s c r i b e d b y C h e n e y (1973) h a v e b e e n i n s t a l l e d in t h e M i n s t e r. 7. At the t i m e the u n d e r p i n n i n g w a s e x e c u t e d, t h e r e w a s v e r y l i t t l e p u b l i s h e d i n f o r m a t i o n o n t h e b e h a v i o u r of o l d m a s s i v e b u i l d i n g s. S i n c e then, T h o m a s & F i s h e r (197 4) h a v e p u b l i s h e d s e t t l e m e n t r e c o r d s for St. P a u l ' s C a t h e d r a l in L o n d o n, w h i c h the a u t h o r (1974) s u b s e q u e n t l y a n a l y s e d. K e r i s e l (1975) p u b l i s h e d m u c h v a l u a b l e i n f o r m a t i o n on the b e h a v i o u r of N o r m a n a n d G o t h i c s t r u c t u r e s. O n a c c o u n t of t h e d i f f i c u l t i e s of a n a l y s i s of s u c h c o m p l e x m a s s i v e s t r u c t u r e s, it is h o p e d t h a t t h e r e s u l t s g i v e n in t h i s p a p e r w i l l b e of a s s i s t a n c e to o t h e r s e n g a g e d in su c h u n d e r p i n n i n g w ork. A C K N O W L E D G E M E N T S T h e r e s t o r a t i o n w o r k w a s u n d e r t a k e n for t h e D e a n & C h a p t e r or Y o r k M i n s t e r by B.M. F e i l d e n, S u r v e y o r t o t h e F a b r i c, O v e A r u p & P a r t n e r s, C o n s u l t i n g E n g i n e e r s, a n d S h e p h e r d C o n s t r u c t i o n Ltd. of York. T h e a u t h o r is g r a t e f u l t o h i s c o l l e a g u e s in O v e A r u p & P a r t n e r s, in p a r t i c u l a r Dr. D.J. Henkel, D.J. D o w r i c k, P. B e c k m a n n a n d F.G. Butler, w h o w e r e d e e p l y i n v o l v e d in t h e w o r k, a n d to Dr. M.A. S t r o u d a n d A.R. W o o d l a n d for t h e i r h e l p f u l c r i t i c i s m s. T h e a c c u r a c y of t h e p r e c i s e l e v e l l i n g is l a r g e l y d u e to the p e r s e v e r a n c e of t h e r e s i d e n t e n g i n e e r, N. Ross. R E F E R E N C E S B r i n c h H a n s e n, J. (1961). A g e n e r a l f o r m u l a for b e a r i n g c a p a c i t y. B u l l e t i n G e o t e k n i s k I n s t i t u t No. 11. T h e D a n i s h G e o t e c h n i c a l I n s t i t u t e. C h e n e y, J.A. (1973). T e c h n i q u e s a n d e q u i p m e n t u s i n g t h e s u r v e y o r s l e v e l for a c c u r a t e m e a s u r e m e n t of b u i l d i n g m o v e m e n t. Symp. on F i e l d I n s t r u m e n t a t i o n, B r i t i s h G e o t e c h n i c a l S o c i e t y, B u t t e r w o r t h s, L o n d o n. C o r b e t t, B.O. (1972). D i s c u s s i o n o n P a p e r 7415S. Y o r k M i n s t e r s t r u c t u r a l r e s t o r a t i o n. P roc. I n s t i t u t i o n o f C i v i l E n g i n e e r s S u p p l e m e n t ( x i ), L o ndon. D o w r i c k, D.J. (1970). T h e u s e of p r e s t r e s s i n g in f o u n d a t i o n s t r e n g t h e n i n g at Y o r k M i n s t e r. G r o u n d Eng. Vol. 3, No. 6, N o v., 14-17, L o n d o n. (British t e c h n i c a l c o n t r i b u t i o n to t h e S i x t h I n t e r n a t i o n a l C o n g r e s s of the F e d e r a t i o n I n t e r n a t i o n a l e de la P r e c o n t r a i n t e, P r a g u e, J u n e 19 70, p u b l i s h e d b y T h e C o n c r e t e S o c i e t y ). D o w r i c k, D.J. & B e c k m a n n, P. (1971). Y o r k M i n s t e r s t r u c t u r a l r e s t o r a t i o n. Proc. I n s t i t u t i o n of C i v i l E n g i n e e r s, L o n d o n, S u p p l e m e n t ( v i ), P a p e r 7415S. K e r i s e l, J. (1975). O l d s t r u c t u r e s in r e l a t i o n t o soil c o n d i t i o n s. G e o t e c h n i q u e 25, No. 3, L ord, J.A. (1974). D i s c u s s i o n o n P a p e r I II/9 St. P a u l ' s C a t h e d r a l - m e a s u r e m e n t s of s e t t l e m e n t s a n d m o v e m e n t s of the s t r u c t u r e. Conf. on S e t t l e m e n t of S t r u c t u r e s, C a m b r i d g e. B r i t i s h G e o t e c h n i c a l S o c i e t y, P e n t e c h Press, M e y e r h o f, G.G. (1951). T h e u l t i m a t e b e a r i n g c a p a c i t y o f f o u n d a t i o n s. G e o t e c h n i q u e, 2, No. 4, P h i l l i p s, A.D. (1975). E x c a v a t i o n s at Y o r k M i n s t e r, F r i e n d s of Y o r k M i n s t e r A n n u a l R e p o r t, T h o m a s, J.B. & F i s h e r, A.W. (1974). St. P a u l ' s C a t h e d r a l - m e a s u r e m e n t of s e t t l e m e n t s and m o v e m e n t s of the s t r u c t u r e. Conf. on S e t t l e m e n t of S t r u c t u r e s, C a m b r i d g e. B r i t i s h G e o t e c h n i c a l S o c i e t y, P e n t e c h Press,
DRILL HOLE # BH-BGC13-FN-01
DILL HOLE # BH-BGC3-FN-0 Drill Method: Mud otary/coring Depth To ock (m): N/A Page of 7 eviewed by: AJB 0 GAVEL (GW) Fine to coarse, sandy, well graded, dense, max particle size = 30 mm, angular to subrounded,
More informationSHEET PILE WALLS. Mehdi Mokhberi Islamic Azad University
SHEET PILE WALLS Mehdi Mokhberi Islamic Azad University Lateral Support In geotechnical engineering, it is often necessary to prevent lateral soil movements. Tie rod Anchor Sheet pile Cantilever retaining
More informationGeneral. DATE December 10, 2013 PROJECT No TO Mary Jarvis Urbandale/Riverside South Development Corporation
DATE December 10, 201 PROJECT No. 10-1121-0260- TO Mary Jarvis Urbandale/Riverside South Development Corporation CC Justin Robitaille, Urbandale Jonathan Párraga, J.L. Richards & Associates Limited FROM
More informationDepth (ft) USCS Soil Description TOPSOIL & FOREST DUFF
Test Pit No. TP-6 Location: Latitude 47.543003, Longitude -121.980441 Approximate Ground Surface Elevation: 1,132 feet Depth (ft) USCS Soil Description 0 1.5 1.5 5.0 SM 5.0 8.0 SM Loose to medium dense,
More informationLimited Geotechnical Engineering Evaluation Classroom Additions Albany County Campus Laramie, Wyoming
Limited Geotechnical Engineering Evaluation Classroom Additions Albany County Campus 2300 Missile Drive, Cheyenne, Wyoming 82001 Phone 307-635-0222 www.stratageotech.com Limited Geotechnical Engineering
More information(C) Global Journal of Engineering Science and Research Management
GEOTECHNCIAL ASSESSMENT OF PART OF PORT HARCOURT, NIGER DELTA FOR STRUCTURAL ANALYSIS Warmate Tamunonengiyeofori Geostrat International Services Limited, www.geostratinternational.com. *Correspondence
More informationJune 9, R. D. Cook, P.Eng. Soils Engineer Special Services Western Region PUBLIC WORKS CANADA WESTERN REGION REPORT ON
PUBLIC WORKS CANADA WESTERN REGION REPORT ON GEOTECHNICAL INVESTIGATION PROPOSED MARTIN RIVER BRIDGE MILE 306.7 MACKENZIE HIGHWAY Submitted by : R. D. Cook, P.Eng. Soils Engineer Special Services Western
More informationChapter 12 Subsurface Exploration
Page 12 1 Chapter 12 Subsurface Exploration 1. The process of identifying the layers of deposits that underlie a proposed structure and their physical characteristics is generally referred to as (a) subsurface
More informationBoreholes. Implementation. Boring. Boreholes may be excavated by one of these methods: 1. Auger Boring 2. Wash Boring 3.
Implementation Boreholes 1. Auger Boring 2. Wash Boring 3. Rotary Drilling Boring Boreholes may be excavated by one of these methods: 4. Percussion Drilling The right choice of method depends on: Ground
More informationAppendix F Laboratory test results
Appendix F Laboratory test results SOIL AND ROCK SAMPLE ANALYSIS LABORATORY TEST REPORT To: Bord Gais Copy: Orla Smyth (kkidd@bge.ie) From: Stephen Watson Laboratory Manager Causeway Geotech Ltd Tel: +44(0)2827666640
More informationAPPENDIX C HYDROGEOLOGIC INVESTIGATION
Figure B-5.7 Figure B-5.8 Preliminary Geotechnical and Environmental Report Appendix C Hydrogeologic Investigation APPENDIX C HYDROGEOLOGIC INVESTIGATION December 21, 2011 WESTSIDE SUBWAY EXTENSION PROJECT
More informationQUESTION BANK DEPARTMENT: CIVIL SUBJECT CODE / Name: CE 2251 / SOIL MECHANICS SEMESTER: IV UNIT 1- INTRODUCTION PART - A (2 marks) 1. Distinguish between Residual and Transported soil. (AUC May/June 2012)
More informationCPT Guide 5 th Edition. CPT Applications - Deep Foundations. Gregg Drilling & Testing, Inc. Dr. Peter K. Robertson Webinar # /2/2013
Gregg Drilling & Testing, Inc. Site Investigation Experts CPT Applications - Deep Foundations Dr. Peter K. Robertson Webinar #6 2013 CPT Guide 5 th Edition Robertson & Cabal (Robertson) 5 th Edition 2012
More informationProject: ITHACA-TOMPKINS REGIONAL AIRPORT EXPANSION Project Location: ITHACA, NY Project Number: 218-34 Key to Soil Symbols and Terms TERMS DESCRIBING CONSISTENCY OR CONDITION COARSE-GRAINED SOILS (major
More informationAPPENDIX A. Borehole Logs Explanation of Terms and Symbols
APPENDIX A Borehole Logs Explanation of Terms and Symbols Page 153 of 168 EXPLANATION OF TERMS AND SYMBOLS The terms and symbols used on the borehole logs to summarize the results of field investigation
More informationDrilled Shaft Foundations in Limestone. Dan Brown, P.E., Ph.D. Dan Brown and Associates
Drilled Shaft Foundations in Limestone Dan Brown, P.E., Ph.D. Dan Brown and Associates Foundation Engineering How we teach our students Fundamental understanding of soil and rock behavior (good!) Focus
More informationGEOTECHNICAL INVESTIGATION REPORT
GEOTECHNICAL INVESTIGATION REPORT SOIL INVESTIGATION REPORT FOR STATIC TEST FACILITY FOR PROPELLANTS AT BDL, IBRAHIMPATNAM. Graphics Designers, M/s Architecture & Engineering 859, Banjara Avenue, Consultancy
More informationModule 1 GEOTECHNICAL PROPERTIES OF SOIL AND OF REINFORCED SOIL (Lectures 1 to 4)
Module 1 GEOTECHNICAL PROPERTIES OF SOIL AND OF REINFORCED SOIL (Lectures 1 to 4) Topics 1.1 INTRODUCTION 1.2 GRAIN-SIZE DISTRIBUTION Sieve Analysis Hydrometer Analysis 1.3 SIZE LIMITS FOR SOILS 1.4 WEIGHT-VOLUME
More informationAppendix A. Producer Statement Advisory Note
Appendix A Producer Statement Advisory Note Ref. No. 17095 26 May 2017 PRODUCER STATEMENT CONSTRUCTION REVIEW (PS4) IMPORTANT ADVISORY NOTE The Building Consent Authority (BCA) frequently requires Producer
More information*** ***! " " ) * % )!( & ' % # $. 0 1 %./ +, - 7 : %8% 9 ) 7 / ( * 7 : %8% 9 < ;14. " > /' ;-,=. / ١
١ ******!" #$ % & '!( ) % * ") +,-./ % 01. 3 ( 4 56 7/4 ) 8%9 % : 7 ;14 < 8%9 % : *7./ = ;-, >/'." Soil Permeability & Seepage ٢ Soil Permeability- Definition ٣ What is Permeability? Permeability is the
More informationCONQUEST ENGINEERING LTD.
CONQUEST ENGINEERING LTD. Geotechnical and Materials Engineers Concrete Technology, Blasting Consultants Construction Quality Assurance / Quality Control 8 Bluewater Road, Bedford, NS BB J6 Phone (9)85-7
More informationTable 3. Empirical Coefficients for BS 8002 equation. A (degrees) Rounded Sub-angular. 2 Angular. B (degrees) Uniform Moderate grading.
Hatanaka and Uchida (1996); ' 20N 20 12N 20 ' 45 A lower bound for the above equation is given as; 12N 15 ' 45 Table 3. Empirical Coefficients for BS 8002 equation A Angularity 1) A (degrees) Rounded 0
More informationwater proofing will relatively long time fully completed) be provided 10 storey building (15x25m) original GWT position 1 sat = 20 kn/m 3
P1 Question: An excavation will be made for a ten storey 15x25 m building. Temporary support of earth pressure and water pressure will be made by deep secant cantilever pile wall. The gross pressure due
More informationLiquefaction and Foundations
Liquefaction and Foundations Amit Prashant Indian Institute of Technology Gandhinagar Short Course on Seismic Design of Reinforced Concrete Buildings 26 30 November, 2012 What is Liquefaction? Liquefaction
More informationA. V T = 1 B. Ms = 1 C. Vs = 1 D. Vv = 1
Geology and Soil Mechanics 55401 /1A (2002-2003) Mark the best answer on the multiple choice answer sheet. 1. Soil mechanics is the application of hydraulics, geology and mechanics to problems relating
More informationGeotechnical Indications Of Eastern Bypass Area In Port Harcourt, Niger Delta
Geotechnical Indications Of Eastern Bypass Area In Port Harcourt, Niger Delta Warmate Tamunonengiyeofori Geostrat International Services Limited, Rivers State, Nigeria www.geostratinternational.com info@geostratinternational.com,
More informationGeology and Soil Mechanics /1A ( ) Mark the best answer on the multiple choice answer sheet.
Geology and Soil Mechanics 55401 /1A (2003-2004) Mark the best answer on the multiple choice answer sheet. 1. Soil mechanics is the application of hydraulics, geology and mechanics to problems relating
More informationSoil Mechanics. Chapter # 1. Prepared By Mr. Ashok Kumar Lecturer in Civil Engineering Gpes Meham Rohtak INTRODUCTION TO SOIL MECHANICS AND ITS TYPES
Soil Mechanics Chapter # 1 INTRODUCTION TO SOIL MECHANICS AND ITS TYPES Prepared By Mr. Ashok Kumar Lecturer in Civil Engineering Gpes Meham Rohtak Chapter Outlines Introduction to Soil Mechanics, Soil
More informationBackground. Valley fills Sites in the Area. Construction over Mine Spoil Fills
Construction over Mine Spoil Fills Wayne A. Karem, PhD, PE, PG, D.GE 2014 KSPE Annual Conference Background Strip mining; mountaintop and contour mining Creates huge quantities of mine spoil The mine spoil
More informationREPORT OF GEOTECHNICAL INVESTIGATION FOR CONSTRUCTION OF AIIMS AT GUNTUR, ANDHRA PRADESH
REPORT OF GEOTECHNICAL INVESTIGATION FOR CONSTRUCTION OF AIIMS AT GUNTUR, ANDHRA PRADESH REPORT NO : GT 1764 CLIENT: DEPUTY GENERAL MANAGER (CIVIL) HSCC (INDIA) LTD. (A Govt. Of India Enterprise) (CONSULTANTS
More informationSOIL CLASSIFICATION CHART COARSE-GRAINED SOILS MORE THAN 50% RETAINED ON NO.200 SIEVE FINE-GRAINED SOILS 50% OR MORE PASSES THE NO.200 SIEVE PRIMARY DIVISIONS GRAVELS MORE THAN 50% OF COARSE FRACTION RETAINED
More information16 January 2018 Job Number: RICHARD NEWMAN C\- CLARK FORTUNE MCDONALD AND ASSOCIATES PO BOX 553 QUEENSTOWN
16 January 2018 Job Number: 50595 RICHARD NEWMAN C\- CLARK FORTUNE MCDONALD AND ASSOCIATES PO BOX 553 QUEENSTOWN CHANSEN@CFMA.CO.NZ STORMWATER DISPOSAL ASSESSMENT Dear Richard, RDAgritech were requested
More informationCONTENTS. 1. GeneralsG Field Investigation WorkG Laboratory Testing Work Surface Soil Description-- 7.
CONTENTS Page 1. GeneralsG 4 2. Field Investigation WorkG 4 3. Laboratory Testing Work--- 5 4. Surface Soil Description-- 7 Appendix A Borehole Location Plan 11 Soil Profile-- 15 Bore Logs--=---- 18 Appendix
More informationK Design Graphs and Charts for Raft Foundations Spanning Local Depressions
K Design Graphs and Charts for Raft Foundations Spanning Local Depressions The reader is advised to read the text in Chapter 13 before using these charts. The charts and figures are repeated here for quick
More informationA6 to Manchester Airport Relief Road. B003 Mill Lane Accommodation Bridge Preliminary Design Report Report No. 1007/704/151
A6 to Manchester Airport Relief Road B003 Mill Lane Accommodation Bridge Report No. 1007/704/151 August 2013 PRELIMINARY DESIGN REPORT Structure Name : Structure Number : Mill Lane Accommodation Bridge
More informationDATE: 5/17/2012. LOGGED BY: Geoff Richards. COMPANY: Tetra Tech EM, Inc. DRILL FOREMAN: Walter
ATTACHMENT 2 Page 1 of 1 B1 0 1 2 FILL, Dry; brownish red; clayey silt and gravel; ~30% gravel size fragments of dark grey microcrystalline (aphanetic), extrusive, igneous, rock 3 B1-4a 1100 B1-4b-duplicate
More informationTP-1 N61E 0 DARK BROWN SANDY SILT (ML) stiff, wet with roots (Disturbed Surficial Soil) DEPTH (FEET) 5 REDDISH BROWN SANDSTONE intensely fractured, weak to friable, deeply weathered, tight (Franciscan
More informationSupplementary Problems for Chapter 7
Supplementary Problems for Chapter 7 Problem 7.1 consolidation test has been carried out on a standard 19 mm thick clay sample. The oedometer s deflection gauge indicated 1.66 mm, just before the removal
More informationChapter 7: Settlement of Shallow Foundations
Chapter 7: Settlement of Shallow Foundations Introduction The settlement of a shallow foundation can be divided into two major categories: (a) elastic, or immediate settlement and (b) consolidation settlement.
More informationConventional Field Testing & Issues (SPT, CPT, DCPT, Geophysical methods)
Conventional Field Testing & Issues (SPT, CPT, DCPT, Geophysical methods) Ajanta Sachan Assistant Professor Civil Engineering IIT Gandhinagar Conventional Field Testing 1 Field Test: In-situ shear strength
More informationAppendix J. Geological Investigation
Appendix J Geological Investigation Appendix J Geological Environment Table of Contents Page 1 INTRODUCTION...J-1 1.1 Purpose of the Investigation...J-1 1.2 Scope of the Investigation...J-1 2 METHODO OF
More informationPhoto 1 - Southerly view across 2700 parking lot toward existing building. Multi-residential building borders western side of property in upper right of view. Photo 2 - Southerly view across 2750 parking
More information4. Soil Consistency (Plasticity) (Das, chapter 4)
4. Soil Consistency (Plasticity) (Das, chapter 4) 1 What is Consistency? Consistency is a term used to describe the degree of firmness of fine-grained soils (silt and clay). The consistency of fine grained
More informationUAS Student Residence
General Notes, Abbreviations and Symbols C100 MATCH LINE - SEE SHEET L6 Existing Site Topographic Conditions C101 MATCH LINE - SEE SHEET L5 Existing Site Topographic Conditions C102 DEPTH(FT.) 5 FROZEN
More informationSoil Mechanics Brief Review. Presented by: Gary L. Seider, P.E.
Soil Mechanics Brief Review Presented by: Gary L. Seider, P.E. 1 BASIC ROCK TYPES Igneous Rock (e.g. granite, basalt) Rock formed in place by cooling from magma Generally very stiff/strong and often abrasive
More informationFoundations of High Rise Buildings
Foundations of High Rise Buildings Prof. Dr.-Ing. Yasser El-Mossallamy Professor of Geotechnical Engineering Ain Shams Univ. Cairo, Egypt c/o Arcadis Consult, Germany y.el-mossallamy@arcadis.de Slide:
More informationSite Investigations and Geotechnical Risk For Underground Construction Greg Raines, PE
August 14, 2017 Site Investigations and Geotechnical Risk For Underground Construction Greg Raines, PE Gregory.Raines@Stantec.com Develop Preliminary Geologic / Geotech Conceptual Model for the Project
More informationEngineer. Engineering. Engineering. (in-ja-neer ) A person trained and skilled in any of the various branches of engineering: a civil engineer
Engineer (in-ja-neer ) A person trained and skilled in any of the various branches of engineering: a civil engineer (Random House Webster s College Dictionary, 1991) CE100 Introduction to Civil Geotechnical
More informationLesson 25. Static Pile Load Testing, O-cell, and Statnamic. Reference Manual Chapter 18
Lesson 25 Static Pile Load Testing, O-cell, and Statnamic Reference Manual Chapter 18 STATIC LOAD TESTING Most accurate method to determine static pile capacity Perform at design or construction stage
More informationAPPENDIX A GEOTECHNICAL REPORT
The City of Winnipeg Bid Opportunity No. 529-2017 Template Version: C420170317 - RW APPENDIX A GEOTECHNICAL REPORT Quality Engineering Valued Relationships KGS Group 2017 Industrial Street Rehabilitation
More informationON THE PREDICTION OF EXPERIMENTAL RESULTS FROM TWO PILE TESTS UNDER FORCED VIBRATIONS
Transactions, SMiRT-24 ON THE PREDICTION OF EXPERIMENTAL RESULTS FROM TWO PILE TESTS UNDER FORCED VIBRATIONS 1 Principal Engineer, MTR & Associates, USA INTRODUCTION Mansour Tabatabaie 1 Dynamic response
More informationHorizontal Directional Drilling: An Approach to Design and Construction. Presenter: John Briand, PE Co-Author: Danielle Neamtu, PE
Horizontal Directional Drilling: An Approach to Design and Construction Presenter: John Briand, PE Co-Author: Danielle Neamtu, PE Presentation Outline General HDD overview Conceptual-level evaluation Detailed
More informationLarge Scale Plate Load Test on Gypsum-Rich Soils
Large Scale Plate Load Test on Gypsum-Rich Soils Howard D. Plewes and Carlos Mejia Klohn Crippen Berger Ltd., Vancouver, British Columbia, Canada ABSTRACT A large scale Plate Load Test was carried out
More informationR.M.HARW & ASSOCIATES LTD. GEOTECHNICAL INVESTIGATION PROPOSED BRIDGE SITE. HELAVA CREEKl MILE MACKENZIE HIGHWAY E-2510 OCTOBER 16, 1973
El R.M.HARW & ASSOCIATES LTD. GEOTECHNICAL INVESTIGATION PROPOSED BRIDGE SITE HELAVA CREEKl MILE 616.4 MACKENZIE HIGHWAY E-2510 OCTOBER 16, 1973 R,M,HARDV & ASSOCIATES LTD. CONSULTING ENGINEERING & TESTING
More informationREGARDING SOME DYNAMIC CHARACTERISTICS OF THE SOILS AND THE LIQUIFACTION POTENTIAL OF SANDS IN SOFIA
REGARDING SOME DYNAMIC CHARACTERISTICS OF THE SOILS AND THE LIQUIFACTION POTENTIAL OF SANDS IN SOFIA Chief Ass. Prof. Ivailo Ivanov University of Architecture, Civil Engineering and Geodesy Department
More informationThe process of determining the layers of natural soil deposits that will underlie a proposed structure and their physical properties is generally
The process of determining the layers of natural soil deposits that will underlie a proposed structure and their physical properties is generally referred to as sub surface investigation 2 1 For proper
More informationGEOLOGICAL PROCESSES AND MATERIALS SGM210
University of Pretoria GEOLOGICAL PROCESSES AND MATERIALS SGM210 23 April 2014 1 SOIL PROFILING According to Jennings, Brink & Williams (1973) Very important part of a geotechnical site investigation.
More informationDry Muliwai Sample Location Map
DMM2 DMM1 P:\AthruR\K838-Makua\GIS\Layouts\Dry Muliwai.mxd.mxd - 3/26/3 - JC DMM3 5 Dry Muliwai Sample Location Map Figure 2-4 P:\AthruR\K838-Makua\GIS\Layouts\orth Background Muliwai.mxd.mxd - 3/26/3
More informationSafe bearing capacity evaluation of the bridge site along Syafrubesi-Rasuwagadhi road, Central Nepal
Bulletin of the Department of Geology Bulletin of the Department of Geology, Tribhuvan University, Kathmandu, Nepal, Vol. 12, 2009, pp. 95 100 Safe bearing capacity evaluation of the bridge site along
More informationCivil Engineering, Surveying and Environmental Consulting WASP0059.ltr.JLS.Mich Ave Bridge Geotech.docx
2365 Haggerty Road South * Canton, Michigan 48188 P: 734-397-3100 * F: 734-397-3131 * www.manniksmithgroup.com August 29, 2012 Mr. Richard Kent Washtenaw County Parks and Recreation Commission 2330 Platt
More informationVerification of a Micropile Foundation
Engineering manual No. 36 Update 02/2018 Verification of a Micropile Foundation Program: File: Pile Group Demo_manual_en_36.gsp The objective of this engineering manual is to explain the application of
More informationS E C T I O N 1 2 P R O D U C T S E L E C T I O N G U I D E - H E L I C A L S C R E W P I L E F O U N D A T I O N S
1. P R O D U C T S E L E C T I O N G U I D E - H E L I C A L S C R E W P I L E F O U N D A T I O N S Helical foundation pile includes a lead and extension(s). The lead section is made of a central steel
More informationProf. B V S Viswanadham, Department of Civil Engineering, IIT Bombay
13 Permeability and Seepage -2 Conditions favourable for the formation quick sand Quick sand is not a type of sand but a flow condition occurring within a cohesion-less soil when its effective stress is
More informationLog of Monitoring Well D58B
Project: Motiva - Monitoring Well and Soil Boring Data Project Location: Delaware City Refinery Project Number: 20240412.W1000 Log of Monitoring Well D58B Sheet 1 of 7 Date(s) Drilled Drilling Method Drill
More informationENCE 3610 Soil Mechanics. Site Exploration and Characterisation Field Exploration Methods
ENCE 3610 Soil Mechanics Site Exploration and Characterisation Field Exploration Methods Geotechnical Involvement in Project Phases Planning Design Alternatives Preparation of Detailed Plans Final Design
More informationAPPLICATION OF GLOBAL STRAIN EXTENSOMETER (GLOSTREXT) METHOD FOR INSTRUMENTED BORED PILES IN MALAYSIA
Paper published in 1 th International Conference on Piling and Deep Foundations, 31 st May 2 nd June, Amsterdam. APPLICATION OF GLOBAL STRAIN EXTENSOMETER (GLOSTREXT) METHOD FOR INSTRUMENTED BORED PILES
More informationReference No S072 APRIL 2012
A REPORT TO SOLMAR DEVELOPMENT CORP. A PRELIMINARY SOIL INVESTIGATION FOR PROPOSED SUBDIVISION DEVELOPMENT NORTHEAST OF SIDEROAD 5 AND 0 LINE TOWN OF ERIN Reference No. 202-S072 APRIL 202 DISTRIBUTION
More information30/03/2011. Eurocode 7 Today and Tomorrow. Ground structures t Slope and Retaining wall design in the Netherlands. Contents
Eurocode 7 Today and Tomorrow Ground structures t Slope and Retaining wall design in the Netherlands Adriaan van Seters Hein Jansen Fugro Ingenieursbureau BV The Netherlands Contents Design Approach 3
More informationFeasibility of dynamic test methods in classification of damaged bridges
Feasibility of dynamic test methods in classification of damaged bridges Flavio Galanti, PhD, MSc., Felieke van Duin, MSc. TNO Built Environment and Geosciences, P.O. Box 49, 26 AA, Delft, The Netherlands.
More informationFOUNDATIONS ON SHRINKING AND SWELLING SOILS (Prediction of Movement, Construction Issues)
FOUNDATIONS ON SHRINKING AND SWELLING SOILS (Prediction of Movement, Construction Issues) by Jean-Louis Briaud, Sangho Moon, Xiong Zhang Department of Civil Engineering, Texas A&M University, College Station,
More informationTHE INSTITUTE OF COST ACCOUNTANTS OF INDIA (ICAI)
THE INSTITUTE OF COST ACCOUNTANTS OF INDIA (ICAI) GEOTECHNICAL INVESTIGATION REPORT FOR PROPOSED PROJECT INSTITUTIONAL BUILDING FOR ICAI AT CBD BELAPUR, NAVI MUMBAI OCTOBER 2012 1281-2012-073 BY THANE
More informationAPPENDIX B: BORING LOGS
New Orleans Levee Systems Independent Levee Hurricane Katrina Investigation Team July, 6 APPENDIX B: BORING S As part of the field investigation 9 borings were performed at the sites of interest, as listed
More informationExperimental Investigation of Interface Stresses between Soil and Laterally Loaded Shaft
Experimental Investigation of Interface Stresses between Soil and Laterally Loaded Shaft K.D. Janoyan & M.J. Whelan Clarkson University, Potsdam, New York, USA ABSTRACT: Presented are results of a field
More informationLANDSLIDES IN THE WHITE MOUNTAIN (GEOTECHNICAL STUDIES AND ENGINEERING TESTS)
J. Al Azhar University Gaza 2004, Vol. 7, NO. 2 P 15-26 LANDSLIDES IN THE WHITE MOUNTAIN (GEOTECHNICAL STUDIES AND ENGINEERING TESTS) Isam G. Jardaneh (1), Jalal Al-Dabeek (2), Abdel hakeem Al-Jawhari
More informationCHAPTER 8 ANALYSES OF THE LATERAL LOAD TESTS AT THE ROUTE 351 BRIDGE
CHAPTER ANALYSES OF THE LATERAL LOAD TESTS AT THE ROUTE 351 BRIDGE.1 INTRODUCTION An important objective of this research is to determine whether accurate analyses of the lateral load-deflection behavior
More informationSoils. Technical English - I 10 th week
Technical English - I 10 th week Soils Soil Mechanics is defined as the branch of engineering science which enables an engineer to know theoretically or experimentally the behavior of soil under the action
More informationUse of Dilatometer in Unusual Difficult Soils a Case Study
Use of Dilatometer in Unusual Difficult Soils a Case Study Mensur Mulabdić University of Osijek, Faculty of Civil Engineering. E-mail: mulabdic@gfos.hr Krunoslav Minažek University of Osijek, Faculty of
More informationTHE STRUCTURAL DESIGN OF PILE FOUNDATIONS BASED ON LRFD FOR JAPANESE HIGHWAYS
THE STRUCTURAL DESIGN OF PILE FOUNDATIONS BASED ON LRFD FOR JAPANESE HIGHWAYS Hideaki Nishida 1,Toshiaki Nanazawa 2, Masahiro Shirato 3, Tetsuya Kohno 4, and Mitsuaki Kitaura 5 Abstract One of the motivations
More informationVALLIAMMAI ENGINEERING COLLEGE
VALLIAMMAI ENGINEERING COLLEGE DEPARTMENT OF CIVIL ENGINEERING SUBJECT CODE : CE6405 YEAR : II SUBJECT NAME : SOIL MECHANICS SEM : IV QUESTION BANK (As per Anna University 2013 regulation) UNIT 1- SOIL
More informationCONQUEST ENGINEERING LTD.
CONQUEST ENGINEERING LTD. Geotechnical and Materials Engineers Concrete Technology, Blasting Consultants Construction Quality Assurance / Quality Control 8 Bluewater Road, Bedford, NS BB J6 Phone (9)85-7
More informationGeotechnical Engineering Study, Conifer Senior High School Football Field Improvements, Conifer, Colorado
2390 South Lipan Street Denver, CO 80223 phone: (303) 742-9700 fax: (303) 742-9666 email: kadenver@kumarusa.com www.kumarusa.com Office Locations: Denver (HQ), Colorado Springs, Fort Collins, and Frisco,
More informationDETAILED INVESTIGATION OF PILES DAMAGED BY HYOGOKEN NAMBU EARTHQUAKE
DETAILED INVESTIGATION OF PILES DAMAGED BY HYOGOKEN NAMBU EARTHQUAKE Kenichi HORIKOSHI 1, Akira TATEISHI 2 And Hiroyasu OHTSU 3 SUMMARY Since the 199 Hyogoken Nambu earthquake, a number of detailed investigations
More informationClay Robinson, PhD, CPSS, PG copyright 2009
Engineering: What's soil got to do with it? Clay Robinson, PhD, CPSS, PG crobinson@wtamu.edu, http://www.wtamu.edu/~crobinson, copyright 2009 Merriam-Webster Online Dictionary soil, noun 1 : firm land
More informationCITY OF VALDEZ Project Title: East Pioneer Reconstruction Project No.: Contract No.: TO: All Recipients Date: April 14, 2014
CITY OF VALDEZ Project Title: East Pioneer Reconstruction Project No.: 13-3-1.32 Contract No.: 11 TO: All Recipients Date: April 14, 214 SUBJECT: Addendum No.1 This seventeen (17) page Addendum forms a
More informationEast Land Quality Forum Drilling Techniques; Old and New
East Land Quality Forum Drilling Techniques; Old and New 1 Introduction Different Drilling Methods Rota-sonic drilling What is it and how does it work? Different types of Rota-Sonic/Sonic Drilling Rigs
More informationSOIL AND AGGREGATE FUNDAMENTALS STUDENT GUIDE AMRC April, 2006 AREA MANAGER ROADS CERTIFICATION PROGRAM FOR EDUCATIONAL PURPOSES ONLY
AREA MANAGER ROADS CERTIFICATION PROGRAM AMRC 2011 SOIL AND AGGREGATE FUNDAMENTALS STUDENT GUIDE FOR EDUCATIONAL PURPOSES ONLY April, 2006 WPC #28013 07/09 2009 by British Columbia Institute of Technology
More informationTABLE OF CONTANINET 1. Design criteria. 2. Lateral loads. 3. 3D finite element model (SAP2000, Ver.16). 4. Design of vertical elements (CSI, Ver.9).
TABLE OF CONTANINET 1. Design criteria. 2. Lateral loads. 2-1. Wind loads calculation 2-2. Seismic loads 3. 3D finite element model (SAP2000, Ver.16). 4. Design of vertical elements (CSI, Ver.9). 4-1.
More information(THIS IS ONLY A SAMPLE REPORT OR APPENDIX OFFERED TO THE USERS OF THE COMPUTER PROGRAM
C A U T I O N!! (THIS IS ONLY A SAMPLE REPORT OR APPENDIX OFFERED TO THE USERS OF THE COMPUTER PROGRAM EQLique&Settle2. THE AUTHOR IS HEREBY RELEASED OF ANY LIABILITY FOR ANY INCORRECT USE OF THIS SAMPLE
More informationEN Eurocode 7. Section 3 Geotechnical Data Section 6 Spread Foundations. Trevor L.L. Orr Trinity College Dublin Ireland.
EN 1997 1: Sections 3 and 6 Your logo Brussels, 18-20 February 2008 Dissemination of information workshop 1 EN 1997-1 Eurocode 7 Section 3 Geotechnical Data Section 6 Spread Foundations Trevor L.L. Orr
More informationIN SITU SPECIFIC GRAVITY VS GRAIN SIZE: A BETTER METHOD TO ESTIMATE NEW WORK DREDGING PRODUCTION
IN SITU SPECIFIC GRAVITY VS GRAIN SIZE: A BETTER METHOD TO ESTIMATE NEW WORK DREDGING PRODUCTION Nancy Case O Bourke, PE 1, Gregory L. Hartman, PE 2 and Paul Fuglevand, PE 3 ABSTRACT In-situ specific gravity
More informationHydro One (Sept 2014) Hydro One (Sept 2014) Hydro One (Sept 2014)
TABLE 1 WELL CONSTRUCTION DETAILS MOE WWR No Well ID Location Installation Date Status Easting Coordinates Northing Source Elevation Screened Interval Screened Material Borehole Well Stick-up Ground Top
More information25th International Conference on Ground Control in Mining
ANALYTICAL INVESTIGATION OF SHAFT DAMAGES AT WEST ELK MINE Tim Ross, Senior Associate Agapito Associates, Inc. Golden, CO, USA Bo Yu, Senior Engineer Agapito Associates, Inc. Grand Junction, CO, USA Chris
More informationGeotechnical Engineering Report
Geotechnical Engineering Report Turner Turnpike Widening Bridge B Bridge Crossing: South 257 th West Avenue Creek County, Oklahoma June 1, 2016 Terracon Project No. 04155197 Prepared for: Garver, LLC Tulsa,
More informationGeotechnical Engineering Report
Geotechnical Engineering Report Turner Turnpike Widening Polecat Creek Bridge (Bridge A) June 1, 2016 Terracon Project No. 04155197 Prepared for: Garver, LLC Prepared by: Terracon Consultants, Inc. TABLE
More informationSupport Reactions: a + M C = 0; 800(10) F DE(4) F DE(2) = 0. F DE = 2000 lb. + c F y = 0; (2000) - C y = 0 C y = 400 lb
06 Solutions 46060_Part1 5/27/10 3:51 P Page 334 6 11. The overhanging beam has been fabricated with a projected arm D on it. Draw the shear and moment diagrams for the beam C if it supports a load of
More informationScour assessment in complex marine soils an evaluation through case examples
Scour assessment in complex marine soils an evaluation through case examples 1 (1)HR Wallingford, Howbery Park, Wallingford, Oxfordshire, OX10 8BA email j.harris@hrwallingford.co.uk, r.whitehouse@hrwallingford.co.uk,
More informationSASKATCHEWAN STRATIGRAPHY GLACIAL EXAMPLE BOULDERS IN GLACIAL DEPOSITS
SASKATCHEWAN STRATIGRAPHY GLACIAL EXAMPLE BOULDERS IN GLACIAL DEPOSITS 51 SASKATCHEWAN STRATIGRAPHY GLACIAL SURFICIAL STRATIFIED DEPOSITS 52 SASKATCHEWAN STRATIGRAPHY GLACIAL EXAMPLE OF SEDIMENT DEPOSITION
More informationManor Farm, Otley Road, Adel - preliminary findings
005/87/ 6 th September 07 Mr G Titchmarsh Titchmarsh & Bagley. Prospect House Sovereign Street Leeds LS BJ Registered in England 07068066 Parkhill Wetherby West Yorkshire LS 5DZ T 097 55 0 www.lithos.co.uk
More informationANALYSIS OF LATERALLY LOADED FIXED HEADED SINGLE FLOATING PILE IN MULTILAYERED SOIL USING BEF APPROACH
INDIAN GEOTECHNICAL SOCIETY, KOLKATA CHAPTER GEOTECHNICS FOR INFRASTRUCTURE DEVELOPMENT KOLKATA 11 th 12 th March 2016, Kolkata, West Bengal, India ANALYSIS OF LATERALLY LOADED FIXED HEADED SINGLE FLOATING
More informationSOIL FORMATION SOIL CLASSIFICATION FOR GEOTECHNICAL ENGINEERS. Soil Properties and Classification
SOIL CLASSIFICATION FOR GEOTECHNICAL ENGINEERS Soil Properties and Classification Soil Formation Soil Types Particle Size Analysis and Grading Characteristics Consistency Indices Engineering classification
More information