XCC群桩限制液化侧向扩展的振动台试验研究  

Shaking table tests on efficiency of improvement of X-section piles against lateral spreading

作　　者：李文闻 陈育民[1,2] 刘汉龙[1,2,3] 杨耀辉 张鑫磊 LI Wen-wen;CHEN Yu-min;LIU Han-long;YANG Yao-hui;ZHANG Xin-lei(Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, China;College of Civil and Transportation Engineering, Hohai University, Nanjing 210098, China;College of Civil Engineering, Chongqing University, Chongqing 400045, China)

机构地区：[1]河海大学岩土力学与堤坝工程教育部重点实验室,江苏南京210098 [2]河海大学土木与交通学院,江苏南京210098 [3]重庆大学土木工程学院,重庆400045

出　　处：《岩土工程学报》2018年第5期945-952,共8页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(51379067,51679072,51420105013);教育部创新团队发展计划(IRT_15R17);高等学校学科创新引智计划(B13024);中央高校基本科研业务费专项资金项目(2015B17314)

摘　　要：地震作用下,缓倾砂土地基会发生液化引发侧向扩展,对构筑物造成严重破坏,而可液化场地中的群桩可控制液化侧向变形的发展。现浇X形混凝土桩（XCC桩）较传统混凝土桩可以节省材料用量,其异形截面对于液化土体的流动变形的控制作用较圆形截面更具优势。开展了倾斜可液化地基中XCC群桩的振动台试验研究,对比了XCC群桩和圆桩群桩对液化侧向扩展变形的影响,同时考虑了群桩布置形式、XCC桩的截面朝向和截面异形效应对于处理效果的影响。结果表明：XCC桩可以较好的限制液化侧向扩展,与未处理场地相比,XCC桩处理场地的侧向位移减少约38%,流动面积减小约50%;在同等材料用量下,XCC桩处理效果优于传统圆桩,其流动面积较圆桩处理场地减少20%;梅花形群桩布置形式限制液化侧向扩展的效果明显好于正方形群桩布置形式;不同XCC桩的截面朝向的处理效果取决于其垂直于液化砂土流动方向的截面宽度,有效截面宽度越大则处理效果越好;XCC桩的截面异形效应能够提高限制液化侧向扩展效果约5%~18%左右。Lateral spreading often occurs in liquefiable sloping ground during earthquake, which causes severe damage to the nearby constructions. Installing piles into sloping ground has been proven to be effective in reducing the lateral displacement. The X-section cast-in-place concrete pile（XCC pile） can save material usage compared with the conventional circular pile. Besides, its special section shape has better effect in restraining the lateral flow of liquefied sand than circular section. A series of 1 g shaking table tests are conducted to verify the efficiency of improvement of XCC piles against liquefaction-induced lateral flow. The mitigation efficiencies of XCC piles and circular pile are compared. Besides, the effects of pile arrangement pattern, orientation of X-section and special section are taken into consideration. The results suggest that the XCC pile can restrict the lateral displacement of liquefied sand, compared with the unimproved case, and the lateral displacement and flow area in XCC pile-improved case are reduced by 38% and 50%, respectively. With the same material usage, the mitigation efficiency of XCC piles is obviously higher than that of circular pile and the flow area is reduced by 20%. The triangular pile arrangement pattern is more effective in restricting the lateral spreading than square pile arrangement pattern. The mitigation efficiency of different orientations of XCC piles depends on the effective section length perpendicular to the direction of lateral flows. The special section effect of XCC piles can increase the mitigation effect by 5%-18%.

关 键 词：振动台试验 XCC桩 液化 侧向变形 流动面积 场地加固 

分 类 号：TU43[建筑科学—岩土工程]