CAPWAP Introduction. 2016, Pile Dynamics, Inc. CAPWAP is a registered trademark of Pile Dynamics, Inc. Load (kn) Displacement (mm) Pile Top Bottom

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CAPWAP Introduction Load (kn) 0.0 1000.0 2000.0 3000.0 4000.0 0.00 Pile Top Bottom Displacement (mm) 5.00 10.

1 CAPWAP Introduction Load (kn) Pile Top Bottom Displacement (mm) Ru = Rs = Rb = Dy = Dx = kn kn kn 18.8 mm 18.8 mm , Pile Dynamics, Inc. CAPWAP is a registered trademark of Pile Dynamics, Inc.

2 CAPWAP is a Signal Matching Program I R We know both Input and Response wave down and wave up But we do not know the System ( static and dynamic soil model )

3 We could plot Measured Force vs Measured Displacement, but

4 . The results would be meaningless, because the dynamic quantities include: Impact and wave effects Static resistance effects Dynamic resistance effects Pile top force in kn Pile top displacement in mm

5 In contrast: CAPWAP calculates the damping resistance and the resistance distribution and the soil stiffness in an iterative procedure.

6 CAPWAP Goals using Force and Velocity measurements and known pile model: Total capacity and resistance distribution (independent of assumed field Jc damping) Simulated static load movement curve. Damping resistance and soil stiffness are by-products from this iterative procedure.

7 Rtoe W DM THE CAPWAP METHOD W UM W UC 1 Set up pile and soil model and assume R shaft and R toe 2 Apply measured W DM to pile model at top and calculate complementary W UC Rshaft 3 Compare W UC with measured W UM 4 Adjust R shaft and R toe 5 If not satisfactory match: Go to Step 2 Repeat until match is satisfactory

8 CAPWAP is an iterative process Final match (good) Adjustments First try (poor)

9 The Pile Model The Pile is divided in N p uniform pile segments of 1 m or less length. F do i F dn i R di Seg. i F un i F uo i R ui R i L i Segment lengths are chosen for equal time increment, t = L i /c i. Each Segment has: impedance Z i,,= E i A i /c i mass m i = Z i t stiffness k i = Z i / t.

10 The Combined Pile and Soil Model Pile Model: Impedance Z i = E i A i /c i Pile Segment Length Li Wave Travel time in Pile t = L i /c i t t t t t t t Soil segment length: L Si = N fac L i Spring (static resistance) Dashpot (dynamic resistance)

11 The Basic CAPWAP Soil Model R ui, q i J i t G End Bearing R t, q t J T Shaft Resistance, Ns times

12 CAPWAP Static Shaft Resistance Model R s R u,s R s u R s quake, q s unloading quake, q s c s R u,n : UN = -R u,n /R u,s

13 CAPWAP Static Toe Resistance Model R t R u,toe R t quake, q t unloading quake, q t c t d Toe gap: t g

14 Pile CAPWAP Damping Model Viscous (Option=0) R d = J C Z v = R U J S v velocity v J s = J c Z/R U Smith (Option=1) R d = R S J S v Combined (Option=2) R d = R S J S v until R S = R U R d = R U J S v after R U has been reached

15 Damping Parameters R d = J C Z v = R U J S v J s = J c Z/R U Smith Shaft Damping value (SS) affected by: Case damping (JS) and Total shaft resistance (RS) SS reduces if JS (shaft) reduces or RS increases Smith Toe Damping value (ST) affected by: Case damping (JS) and Total shaft resistance (RT) ST reduces if JT (toe) reduces or RT increases Total damping defined by { JS plus JT } Work with JS and JT (and then review SS and ST) Changing balance of JS and JT, or RS and RT, affects the Smith Damping values SS and ST

16 CAPWAP Unknowns in General R ui : N S values at shaft +1 value at toe q i : J i : N S values at shaft +1 value at toe N S values at shaft +1 value at toe 1 shaft + 1 toe unloading quake multiplier 1 shaft unloading level + 1 toe plug + 1 toe gap 1 toe damping option + 4 rad. damping values Total 3 N S + 13 unknowns + trimming parameters For 20 m pile penetration: 43 unknowns

17 CAPWAP Unknowns - Normally Main Parameters R ui : N S values at shaft +1 value at toe J i : 1 value at shaft +1 value at toe q i : 1 value at shaft +1 value at toe Other Common Parameters q unloading : 1 value at shaft +1 value at toe 1 Shaft unloading level 1 toe plug, 1 toe damping option, 1 toe gap For 20 m pile penetration: 21 unknowns

18 CAPWAP Record Divisions 2L/c Shaft Res. Distr. develops Toe Res. and total Capacity develops Unloading develops t r

19 CAPWAP Match Quality Period I 2L/c II tr+3 ms III tr+5ms tr IV 25ms Overlapping periods MQ = Σ Period Σ time ABS[F M -F C ] / FMX + BCP BCP = Δ SET [mm] - 1 0

MQ penalty: difference of final set in mm - 1 Calculated final set depends on and is corrected by:

20 Check calculated final set (blow count) How is final set (blow count) calculated? Average of final set of all segments How does calculated final set (blow count) affect match quality? MQ penalty: difference of final set in mm - 1 Calculated final set depends on and is corrected by: acceleration adjustment total resistance change (static and dynamic) quakes unloading parameters rechecking measured final set

21 Signal Matching Example

22 Working with Wave-Up R U = 782 kips R T = 68 kips J S /J T =.05/.15 s/ft (J CS /J CT =.75/.22) Q S /Q T =.10/.12 R U = 782 kips R T = 400 kips Only change is increase percentage of end bearing R U = 782 kips R T = 600 kips R U = 782 kips R T = 705 kips J S /J T =.45/.02 s/ft Q S /Q T =.10/.12

23 Working with Wave-Up R U /R T = 782/705 kips J S /J T =.45/.02 s/ft (J CS /J CT =.75/.22) Q S /Q T =.10/.12 R U /R T = 782/705 kips J S /J T =.30/.05 s/ft (J CS /J CT =.50/.76) Only change is damping constants Prev. R U /R T = 782/702 kips J S /J T =.29/.05 s/ft (J CS /J CT =.50/.76) Only change is resistance distribution

24 Working with Wave-Up R U /R T = 782/702 kips J S /J T =.29/.05 s/ft (J CS /J CT =.50/.76) R U /R T = 765/686 kips J S /J T =.28/.06 s/ft (J CS /J CT =.48/.82) Reduce capacity and change damping constants R U /R T = 765/686 kips J S /J T =.26/.07 s/ft (J CS /J CT =.44/.97) Q S /Q T =.06/.12 Unloading Parameters Pretty good match: let s quit Change quakes and damping constants and unloading

25 Plotted Output

26 DE 70B, HP 14 X 89; Blow: 627 CAPWAP MKT Engineers, Inc. GRL Damping Factor Case Quake (% of loading quake) Unloading Level (% of Ru) Reloading Level (% of Ru) 78 Unloading final set = in; blow count = 240 b/ft Observed: final set = in; blow count = 1323 b/ft Observed: Table Output: Soil Parameter Table EX2; CLARK; SOFT-ROCK; Pile: EX-2 Test: 02-Jun-1993 CAPWAP FINAL RESULTS R i J i q i Total CAPWAP Capacity: 764.6; along Shaft 79.5; at Toe kips ft ft kips kips kips kips/ft ksf s/ft in Avg. Skin Toe Soil Model Parameters/Extensions Skin Toe CAPWAP match quality: 2.88 (Wave Up Match)

27 DE 70B, HP 14 X 89; Blow: 627 CAPWAP MKT Engineers, Inc. GRL Dist. max. min. max. max. max. max. max. Pile Below Force Force Comp. Tens. Trnsfd. Veloc. Displ. Sgmnt (T = 27.2 ms) Absolute (T = 44.2 ms) 87.5 Extrema Table Table Output EX2; CLARK; SOFT-ROCK; Pile: EX-2 Test: 02-Jun-1993 EXTREMA TABLE No. Gages Stress Stress Energy Case Method Table ft kips kips ksi ksi kip-ft ft/s in CASE METHOD J = = RS RMX RSU RAU= (kips); RA2= (kips) Current CAPWAP Ru= (kips); Corresponding J(Rs)= 0.21; J(Rx)= ft/s ft/s kips kips kips in in kip-ft kips

28 CAPWAP Help Features HC CAPWAP Variable Help HR CAPWAP Resistance vs Displacement Help HM Match suggestions

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