桩周土含水率对三维碎石桩基承载力影响的实验.doc

桩周土含水率对三维碎石桩基承载力影响的实验刘源, 徐同桐, 赵宪锋（兰州交通大学 土木工程学院，兰州 730070）［摘要］ 探讨桩周土含水率对碎石桩桩体的荷载传力效率的影响通过含水桩周土与碎石桩组成的复合地基的室内三维荷载试验，和对碎石桩两端应力的计算处理，详细分析了碎石桩的桩长、截面形状和桩周土含水率对桩体承载力的影响结果表明：当桩周土含水率为11.6%时，长桩桩体分担荷载最大；当为较低和较高的含水率时，桩体分担的荷载部分减小，底部应力较小给出了碎石桩复合地基由刺入破坏向鼓胀破坏转变的关键参数——临界长径比含水率不同，桩体对应的临界长径比不同对应于试验中所采用的含水率（7.89%～16.01%），桩体临界长径比为20～22.5，且临界长径比随含水率的增加呈先增加后减小的变化趋势［关键词］ 三维碎石桩；荷载；桩周土；含水率；临界长径比Experimental study on influence of soil moisture content in 3D gravel pile foundation on its bearing capacityLIU Yuan, XU Tongtong, ZHAO XianfengSchool of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, ChinaAbstract: The influence of soil moisture content in the gravel pile on the load transfer efficiency of the gravel pile is discussed. Indoor 3-D load test of composite foundation composed of water-bearing pile surrounding soil and gravel pile and the calculation of the stress at both ends of the gravel pile are carried out, with the detailed analyses of pile length, section shape and soil moisture content. It shows that when the moisture content of the surrounding soil is 11.6%, the load of the long pile is the largest; when moisture content is lower and higher, the load shared by the pile is reduced and the stress at the pile bottom is smaller. The critical slenderness ratio λcr which is a key parameter of the transition of the gravel pile composite foundation from the piercing failure to the bulging failure is obtained. It is obvious that if the moisture content is different, the critical length to diameter ratio of the pile is different. Corresponding to the moisture content (7.89%~16.01%) used in the test, when the ratio λcr of the pile is in the range of 20~22.5, it increases first and then decreases with the increment of moisture content.Key words: 3D gravel pile; load; soil around pile; moisture content; critical slenderness ratio。