Design Guideline for Buried Hume Pipe Subject to Coupling Forces

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1 Design Guideline fo Buied Hume Pipe Sujec o Coupling Foces Won Pyo Hong 1), *Seongwon Hong 2), and Thomas Kang 3) 1) Depamen of Civil, nvionmenal and Plan ngineeing, Chang-Ang Univesiy, Seoul 06974, Koea 2) ngineeing Reseach Insiue, Seoul Naional Univesiy, Seoul 08826, Koea 3) Depamen of Achiecue and Achiecual ngineeing, Seoul Naional Univesiy, Seoul 08826, Koea, 3) kang@snu.ac.k ABSTRACT A full-scale field es was pefomed on piled emankmen o invesigae he esisance effec of movemen of sof gound. mankmen load esuls in oh he selemen and laeal defomaion of sof gound, inducing sevee damage and eakage of he uied Hume pipe in sof gound. I was oseved ha he veical and hoizonal movemen linealy inceased unde he consan emankmen loads. This is called coupling effec. To quaniaively evaluae he coupling effec, he Coupling Aea was deived and analyzed wih he efficiency of load ansfe. 1. INTRODUCTION The uiliy pipes fo supply of eleciciy, gas, and wae have een uied and insalled in eclamaion in maine aea ecause of ecen gowing demand fo uan infasucues in coasal eclaimed land (Tokimasu e al. 2012; Zhou e al. 2014; Song e al. 2015). In geneal, he emankmen was filled nea he uied uiliy pipes in he coasal zone and he significan loads can cause laeal and veical movemen of sof gound and evenually funcional damage o he pipe (Hong 2005; Hong and Lee 2009). Theefoe, he deailed design guidelines and esimaion mehod fo he laeal and hoizonal flow of sof gound ae definiely needed o minimize such a damage. In his pape, he innovaive evaluaion mehod is poposed and compaed wih he efficiency of load ansfe y soil aching heoy. Figue 1 demonsaes a schemaic pocess of Hume pipe uied in sof soil whee he emankmen was filled. Laeal movemen iniially occus due o he emankmen filling and he laeal flow can esul in he laeal eah pessue on he uied Hume pipe. 1) meius Pofesso 2) Posdocoal Reseache 3) Associae Pofesso

2 mankmen filling Laeal movemen Buied Hume pipe Sof soil Fig. 1 Buied Hume pipe sujec o laeal flow of sof soil caused y emankmen filling 2. PIL-SUPPORTD MBANKMNT AND SOIL ARCHING THORY The pinciple of he piled emankmen is o diecly suppo emankmen loads y piles (see Figue 2). The significan emankmen loads ae ansfeed o a edock y he piles hough he soil aching mechanism. The laeal movemen of sof soil induced y he emankmen loads is effecively educed ecause he appoximaely 70% of emankmen loads is ansfeed o a fim laye. mankmen filling Buied Hume pipe Sof soil piles Bedock Fig. 2 Pile-suppoed emankmen Hong e al. (2007) poposed a heoeical equaion of he veical load P (kn/m) v applied o a eam ased on he geomeic configuaion of he soil aching zone in Fig. 3. The equaion is expessed in q. (1) mankmen Oue aching zone 1 H Inne aching zone H1 Soil wedge H2 2 Sof gound o D2 Cap eam Fig. 3 Soil aching mechanism (Hong e al. 2007) D1 Piles

3 N N cn N 2 1 N 2 1 N 1 Pv HD H H H D (1) whee N = an 2 (/4+/2), H is he heigh of emankmen fills (m), H 1 (= 1 ) is he heigh (m) a he cown of he oue soil ach, H 2 ( ) is he heigh (m) a he cown of he 2 inne soil ach, D 1 and D 2 ae he cene-o-cene disance (m) and clea disance eween he eams, especively, c is he cohesion (kn/m 2 ), is he inenal ficion angle, and is he uni weigh (kn/m 3 ) of he emankmen fills. The efficiency of load ansfe f is defined as a aio of he veical load P v o he oal emankmen load in q. (2) f Pv 100(%) D H 1 (2) 3. FULL-SCAL TST ON MBANKMNT A full-scale expeimen was conduced on piled emankmen o invesigae he esisance effec of movemen of sof gound in Shiwha egion of Ansan Ciy. The peiod of he expeimens was 70 days and he expeimenal measuemens in he emankmen wihou einfocemen wee employed as a efeence. Fig. 4 exhiis plane view of he full-scale expeimen on emankmen I6 I4 I2 Buied pipe S3 S2 S I5 I3 I1 Region 3 Regoin 2 Region Inclinomee Selemen plae Plane view (Uni: m)

4 Fig. 4 Plane view of full-scale es on emankmen 4. RSULTS AND DISCUSSSIONS The emankmen filling esuls in he hoizonal and veical movemen of he sof soil, and he piled emankmen can effecively esain such a selemen and laeal displacemen of sof gound. In ode o quaniaively deemine he esaining effec of oh movemens, he Coupling Aea (CA o A ) (cm 2 ) was deived and expessed in q.(3). 1 A (3) 2 v h whee v is he selemen of uied pipe (cm) and h is he laeal displacemen of sof gound a suface (cm). The efficiency of einfocemen deemined y he CA is wien as A A A o P 100(%) whee A is he CA in he aea of he emankmen wihou einfocemen and A P is he CA in he egion of he piled emankmen. Hee, supescip o epesens locaion (e.g., sands fo he oe of emankmen and signifies he ack of pipe). The efficiency of einfocemen a he oe of emankmen was 71.8% (solid ed line), while he efficiency of piled emankmen a he ack of he pipe was deemined o e aou 60.2% (dashed line), as shown in Fig. 5(a). In Fig. 5(), he efficiency of he CA a he oe of emankmen a a deph of 1.5 m was calculaed o e appoximaely 71.2 % (solid ed line), wheeas he efficiency a he ack of he pipe was 56.9% (dashed line). These expeimenal esuls indicae ha 1) aou 30% of he emankmen load was ansfeed o he sof gound, 2) he efficiency of einfocemen ased on he CA does no depend on he deph since he diffeence eween he efficiencies a suface and a deph of 1.5 m ae appoximaely 0.6% a oe and 3.3% a ack, and 3) he CA a suface can have e used o deemine he esaining effec and will e a vey useful value fo developing design guidelines ha may miigae he damage o he uied pipe. (4)

5 fficiency (%) fficiency (%) f f a oe of emankmen a ack of pipe Time (days) 20 0 a oe of emankmen a ack of pipe Time (days) (a) A suface () A a deph of 1.5m Fig. 5 fficiency analysis y he Coupling Aea: (a) a suface; and () a a deph of 1.5 m 5. CONCLUSIONS In his pape, he novel em, called he CA, o evaluae he coupling effec of sof gound induced y significan emankmen loads was poposed and employed o compae i wih he efficiency of load ansfe. The efficiency deemined y he CA showed good ageemen wih he efficiency calculaed y soil aching heoy. Theefoe, he CA will e a vey useful value fo developing design guidelines of uied pipe. RFRNCS Hong, W.P. (2005), Laeal soil movemen induced y unsymmeical suchages on sof gounds in Koea, IW-SHIGA2005, pp Hong, W.P. and Lee, K.W. (2009), valuaion of laeal movemen of piled idge aumen undegoing laeal soil movemen in sof sound, Maine Geoesouces and Geoechnology, 27, pp Hong, W.P., Lee, J.H., and Lee, K.W. (2007), Load ansfe y soil aching in pilesuppoed emankmens, Soils and Foundaion, 47(5), Song, Y.S., Bov, M.L., Hong, W.P., and Hong, S. (2015), Behavio of veical pessue imposed on he oom of a ench, Maine Geoesouces and Geoechnology, DOI: / X Tokimasu, K., Tamua, S., Suzuki, H., and Kasumaa, K. (2012), Geoechnical polems in he 2011 Tohoku Pacific ahquake, 9h Inenaional Confeence on

6 Uan ahquake ngineeing/ 4h Asia Confeence on ahquake ngineeing, Mach 6-8, 2012, Tokyo Insiue of Technology, Tokyo, Japan Zhou, D.N., Shang, Q., Xiao, B. (2014), Analysis of plafom on piles applicaion on defomaion conol of undegound pipe in eclamaion aeas, Applied Mechanics and Maeials, , pp

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