堆载作用下单桩中性点位置与负摩阻力特性研究  

Study on Neutral Point Position and Negative Friction Resistance of Single Pile under Heap Loading

作　　者：范孟华[1] 闫保衡 朱润朝 王凯 FAN Menghua;YAN Baoheng;ZHU Runchao;WANG Kai(School of Civil Engineering and Architecture,Henan University,Henan Kaifeng 475004,China)

机构地区：[1]河南大学土木建筑学院,河南开封475004

出　　处：《河南大学学报（自然科学版）》2022年第3期329-336,共8页Journal of Henan University:Natural Science

基　　金：国家自然科学基金资助项目(51508163)。

摘　　要：为了探究承台外围土体出现上部堆载作用时,桩身负摩阻力和中性点位置在这一过程中的变化特性,利用室内模型实验和有限元软件数值模拟两种方法.首先在室内模型实验中使用应变仪采集桩身各处应变片产生的数值,之后建立单桩数值模型进行有限元分析,结合两方实验结果分析桩身负摩阻力和中性点位置在施加堆载后的初期,以及随堆载等级增加时的变化特征,最终得出以下结论:承台外围土体的堆载作用使桩身轴力原本随深度递减的变化趋势,变为了轴力上升段和轴力下降段,同样,堆载作用也使桩身上部出现桩侧负摩阻力,而桩身下部正摩阻力区间相较堆载前变化不大,仅是正摩阻力数值的大小随着堆载等级增加而增大,桩身中性点位置在堆载等级增大的过程中逐渐向桩的底部移动.In order to explore the change characteristics of pile negative friction resistance and neutral point position under Upper loading effect of soil around cap,we have used indoor model test and finite element numerical simulation.Firstly,in the indoor model experiment,the strain gauge is used to collect the values generated by strain gauges around the pile body,and then establish the numerical model of single pile for finite element analysis.Combined with the test results of two sides,the change characteristics of negative friction resistance and neutral point position of pile body in the early stage after loading and with the increase of loading grade are analyzed.The conclusions are as follows:The pile shaft axial force decreases with the depth due to the surcharge effect on the periphery of the foundation slab,which changes into the upward section and the downward section of the axial force,and also causes negative friction of pile side to appear on top of pile body.Similarly,the pile side negative friction occurs in the upper part of the pile body,and the positive friction resistance in the lower part of the pile body does not change much,only the value of the positive friction resistance increases with the increase of the load level.The neutral point position of pile moves to the bottom of pile with the increase of load level.

关 键 词：桩基础 堆载作用 负摩阻力 中性点位置 数值模拟 

分 类 号：TU473.2[建筑科学—结构工程]