INFLUENCE OF ECCENTRICITY ON TWO-PILE FOUNDATION SUBJECTED TO LATERAL LOADING
KONG Linggang1，2，GU Ming1，2，CHEN Renpeng1，2，CHEN Yunmin1，2
(1. Institute of Geotechnical Engineering，Zhejiang University，Hangzhou，Zhejiang 310058，China； 2. Key Laboratory of Soft Soils and Geoenvironmental Engineering of Ministry of Education，Zhejiang University，Hangzhou，Zhejiang 310058，China)
Abstract：A large scale model test of two-pile foundation in saturated silt is carried out to investigate the response under eccentric lateral loading. An ABAQUS numerical model is built and validated by the model test result. The effect of eccentricity of applied lateral loading on the behavior of the foundation is further studied using the validated model. It is found that the applied load-horizontal displacement curves of the pile cap of the two-pile foundation are close to a laterally loaded single pile curve in shape. The lateral stiffness decreases with the increasing eccentricity of the applied load. Eccentricity can induce significant difference in pile-head shearing between the two piles. The pile next to the load point undertakes more shear force and the pile-head shear resistance of another pile can be opposite to its displacement in direction under a certain eccentricity. The torsional rigidity of the individual piles is far greater than that of a corresponding single pile subjected to torsion because of the deflection-torque coupling effect in the piles，but the influence of the coupling effect decreases with the increasing eccentricity. Both torsional and lateral resistances of the individual piles contribute to resist the applied torque；and the contribution of torsional resistances of the individual piles to the applied torque significantly decreases with the increasing applied load.
VICKERY BJ. Wind effects on building and structure-critical unsolved problems[C]// Proceedings of the IAHR/IUTAM Practical Experiences with Flow-induced Vibrations Symposium.Karlsruhe，Germany：[s. n.]，1979：823-828.
[2]
陈仁朋，王书行，孔令刚，等. 不同水平偏心距下群桩内力变化规律试验研究[J]. 岩石力学与工程学报，2011，30(3)：603-609. (CHEN Renpeng，WANG Shuhang，KONG Linggang. Test investigation on distribution of internal forces in pile groups under different lateral eccentricities[J]. Chinese Journal of Rock Mechanics and Engineering，2011，30(3)：603-609.(in Chinese))
[3]
KONG L G，ZHANG L M. Centrifuge modeling of torsionally loaded pile groups[J]. Journal of Geotechnical and Geoenvironmental Engineering，2007，133(11)：1374-1384.
[4]
KONG L G，ZHANG L M. Experimental study of interaction and coupling effects in pile groups subjected to torsion[J]. Canadian Geotechnical Journal，2008，45(7)：1006-1017.
[5]
ZHANG L M，KONG L G.Centrifuge modeling of torsional response of piles in sand[J]. Canadian Geotechnical Journal，2006，43(5)：500-515.
[6]
王书行. 水平偏心荷载下群桩受荷性状模型试验及设计方法研究[硕士学位论文][D]. 杭州：浙江大学，2011.(WANG Shuhang. Model tests investigation and design method of the behavior of the pile group under eccentrically lateral loading[M. S. Thesis][D]. Hangzhou：Zhejiang University，2011.(in Chinese))
[7]
陈仁朋，张革强，孔令刚，等. 饱和及非饱和粉土中扩底桩极限上拔承载力大尺寸模型试验研究[J]. 岩石力学与工程学报，2010，29(5)：1 068-1 074.(CHEN Renpeng，ZHANG Geqiang，KONGLinggang，et al. Large-scale tests on uplift ultimate bearing capacitiesof enlarged base piles in saturated and unsaturated silty soils[J].Chinese Journal of Rock Mechanics and Engineering，2010，29(5)：1068-1074.(in Chinese))
[8]
张革强. 非饱和土中输电铁塔扩底桩上拔特性模型试验及理论研究[硕士学位论文][D]. 杭州：浙江大学，2010.(ZHANG Geqiang. Model tests and theory analysis of enlarged piers for transmission line foundations in unsaturated soils[M. S. Thesis][D]. Hangzhou：Zhejiang University，2010.(in Chinese))
[9]
朱 斌，任 宇，陈仁朋，等. 竖向下压循环荷载作用下单桩承载力及累积沉降特性模型试验研究[J]. 岩土工程学报，2009，31(2)：186-193.(ZHU Bin，REN Yu，CHEN Renpeng，et al. Model test on bearing capacity and accumulated settlement of single pile subjected to axial cyclic loading[J]. Chinese Journal of Geotechnical Engineering，2009，31(2)：186-193.(in Chinese))
[10]
朱 斌，朱瑞燕，罗 军，等.海洋高桩基础水平大变位性状模型试验研究[J]. 岩土工程学报，2010，32(4)：521-530.(ZHU Bin，ZHU Ruiyan，LUO Jun，et al. Model tests on characteristics of ocean and offshore elevated piles with large lateral deflection[J]. Chinese Journal of Geotechnical Engineering，2010，32(4)：521-530.(in Chinese))
[11]
罗军. 船舶撞击作用下高桩的水平大变形性状及柔性护墩桩式防撞系统研究[硕士学位论文][D]. 杭州：浙江大学，2008.(LUO Jun. Study on large deformation characteristics of elevated pile subjected to ship impact and flexible piled anti-collision system[M. S. Thesis][D]. Hangzhou：Zhejiang University，2008.(in Chinese))
[12]
郭杰锋. 高桩基础防撞试验及防撞设计新方法研究[硕士学位论文][D]. 杭州：浙江大学，2010.(GUO Jiefeng. Experimental study on anti-collision of high-elevated pile foundations and new anti-collision design methods[M. S. Thesis][D]. Hangzhou：Zhejiang University，2010.(in Chinese))
[13]
JIA G W，ZHAN T L T，CHEN Y M，et al. Performance of a large- scale slope model subjected to rising and lowering water levels[J]. Engineering Geology，2009，106(1/2)：92-103.
[14]
孔令刚，张革强，陈仁朋，等. 土体含水量对扩底桩上拔承载力影响研究[J]. 岩石力学与工程学报，2011，30(增2)：3755-3762. (KONG Linggang，ZHANG Geqiang，CHEN Renpeng. The influence of water content on uplift ultimate capacity of enlarged base piles in unsaturated silt[J]. Chinese Journal of Rock Mechanics and Engineering，2011，30(Supp.2)：3755-3762.(in Chinese))
2013, Vol. 32 
