长期荷载下有侧向约束柔性桩复合地基试验  

Experimental Study of Bearing Behavior of Composite Foundation with Flexible Pile and Lateral Restraint at Long-term Load

作　　者：吴有平[1] 张可能[1] 刘杰[2] 何杰[2] 

机构地区：[1]中南大学地球科学与信息物理学院,有色资源与地质灾害探查湖南省重点实验室,长沙410083 [2]湖南工业大学土木工程学院,湖南株洲412008

出　　处：《上海交通大学学报》2014年第11期1568-1573,共6页Journal of Shanghai Jiaotong University

基　　金：国家自然科学基金项目(51078140;51108176)资助

摘　　要：为探讨长期荷载作用下柔性桩复合地基的工作性状,进行了有无侧向约束条件下夯实水泥土桩复合地基的长期荷载对比试验.在复合地基表面埋设沉降标,量测了桩体和土体沉降值,得到了桩和土的沉降随时间的变化规律;通过在桩间土表面、桩顶、桩端埋设土压力盒和在桩身埋设内贴应变片PVC管量测应力值,获得了桩顶与土顶应力、桩-土应力比、桩身轴力随时间发展的变化规律.试验结果表明：在长期荷载作用下,设置了约束长桩夯实水泥土桩复合地基的工作性状明显优于无约束夯实水泥土桩复合地基的工作性状——大幅度缩短了进入沉降稳定时间（约为64%）,减小工后沉降量（约为29%-42%）,降低桩-土应力比约39%;明显地调整了桩身轴力分布.分析认为：采用柔性桩加固软土路基时,在加固区边缘设置刚性长约束桩,能有效地控制路基的工后沉降,提高路基的承载性能.In order to study the bearing behavior of composite foundation with flexible pile at long-term load, comparative experiments of composite foundation with rammed soil-cement pile with or without lateral restraint at long-term load were conducted. Settlement marks were laid on the surface of composite foundation to measure the sedimentation of pile and soil, from which the variation law of the sedimentation of pile and soil with time could be obtained. By laying earth pressure cells on the surface and bottom of the foundation and building PVC tube with stain gauge in pile shaft to measure the stress value, the stress vat iation of pile top and soil top, the stress ratio of pile soil and pile shaft tress change with time were analyzed. The results of comparative tests show that at long-term load, the performance of composite foundation of rammed soil-cement pile with lateral constraint length piles is obviously better than that without lateral restraint, which can greatly shorten the time step in stable phase （approximately 64%） and reduce the settlement after construction （approximately 29% to 42%）, and decrease the pile-soil stress ratio approximately 39%, hence adjust the distribution of axial force of pile shaft significantly. It can be acknowledged that when soft soil is treated with flexible pile, the settlement after construction can be effectively reduced and bearing capacity of subgrade can be improved if rigid long pile is set as lateral restraint.

关 键 词：长期荷载 侧向约束 夯实水泥土桩 复合地基 模型试验 

分 类 号：TU447[建筑科学—岩土工程]