嵌岩桩负摩阻力现场试验与计算方法研究  

Field test and calculation method of negative skin friction of rock-socketed piles

作　　者：吴爽爽 胡新丽[1] 章涵[1] 周昌 龚辉 WU Shuang-shuang;HU Xin-li;ZHANG Han;ZHOU Chang;GONG Hui(Faculty of Engineering,China University of Geosciences,Wuhan,Hubei 430074,China;Guizhou Bridge Construction Group Co.,Ltd.,Guiyang,Guizhou 550001,China)

机构地区：[1]中国地质大学(武汉)工程学院,湖北武汉430074 [2]贵州桥梁建设集团有限责任公司,贵州贵阳550001

出　　处：《岩土力学》2019年第9期3610-3617,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金重点项目（No.41630643）;国家重点研究发展计划（973计划）（2017YFC1501302）~~

摘　　要：桩-土剪切位移对桩基负摩阻力发展有重要的影响。在既有研究的基础上,通过桩周土体沉降与桩身应变的监测结果建立了计算桩-土剪切位移量的方法。利用该方法对浅中层桩-土监测数据进行分析,确定了在桩顶自由条件下该试验场地桩-土剪切位移量在4~5 mm;对于深层桩-土没有达到该剪切位移量,负摩阻力则无法发挥至极值。根据负摩阻力的发挥特征,改进了规范中嵌岩桩负摩阻力的计算方法,该方法同时考虑了桩周土竖向有效应力与桩土剪切位移的影响。使用该方法计算的负摩阻力与实测结果较为吻合,获得的下拉荷载能够达到安全与经济的效果,可供工程设计参考、借鉴。The pile-soil shear displacement has a significant influence on the development of negative skin friction of piles. Based on current research, a calculation method of plie-soil shear displacement was established by the monitoring results of the pile strain and the soil settlement in the field test. This method was used to analyze the monitoring data of pile and soil in the shallow middle layer, and then the shear displacement of pile and soil was determined to be 4-5 mm under the condition of free pile top in the test. However, the negative skin friction was unavailable to reach its extreme value when the shear displacement of deep pile and soil did not reach the above value. In addition, according to the development characteristics of negative skin friction, its calculation in the specifications was improved by considering both the vertical effective stress of soil around piles and the pile-soil shear displacement. The negative skin friction calculated by this improved method has a good correspondence with the test results. The obtained dragload can achieve a safe, economical effect, which can offer references for engineering design.

关 键 词：桩-土剪切位移 负摩阻力 嵌岩桩 有效应力法 下拉荷载 

分 类 号：TU473[建筑科学—结构工程]