红黏土地层静压闭口管桩残余应力模型试验分析

发布时间：2018-11-07 08:01

【摘要】：在典型的上硬、下软红黏土地层中静压管桩滞留的残余应力对基桩承载特性有较大影响。通过自行设计模型试验设备进行红黏土地层单、群桩静压闭口管桩室内试验,分析3种桩径下静压单、群桩残余应力的变化规律及时间效应。结果表明,静压管桩桩身残余应力沿桩身从上到下先增大后变小,呈折线型分布;对于典型的红黏土上硬、下软地层,桩端持力层位于硬塑层和可塑层时,桩身和桩端残余应力均较小;当管桩压入到基岩持力层后桩端受约束增强,桩身和桩端残余应力明显增大;静压单桩完成后静置初期桩身残余应力时间效应比较明显,减小幅度较大,复压后而后随着休止时间的延长,桩身残余应力呈指数型衰减至一较低稳定值;静载试验时忽略残余应力就将认为整个桩身所受压力偏小,偏大计算中性面以上侧摩阻力7.97%,偏小计算中性面以下侧摩阻力8.33%和桩端阻力2.29%。
[Abstract]:The residual stress of static pressure pipe pile in the typical soft red clay stratum has great influence on the bearing characteristics of the foundation pile. Through self-designed model test equipment, the laboratory tests of red clay single and group pile static pressure closed pipe pile are carried out, and the variation law and time effect of three kinds of pile diameter static pressure single and group pile residual stress are analyzed. The results show that the residual stress of the static pressure pipe pile body increases first from top to bottom and then becomes smaller, showing a broken line distribution. For typical red clay upper and lower soft stratum, the residual stress of pile body and pile end is smaller when the pile end bearing layer is located in hard plastic layer and plastic layer. When the pipe pile is pressed into the bearing layer of the bedrock, the pile end is restrained and the residual stress of the pile body and the pile end increase obviously. The time effect of residual stress in the initial statics of static single pile is obvious, and the amplitude of reduction is larger. After repressing, the residual stress of pile decreases exponentially to a lower stable value with the prolongation of the rest time. If the residual stress is ignored in the static load test, the pressure on the whole pile body will be considered to be small, and the lateral frictional resistance above the neutral plane will be calculated by 7.97, the lateral friction at the bottom of the neutral plane by 8.33% and the pile tip resistance by 2.29%.
【作者单位】：广西科技大学土木建筑工程学院;哈尔滨工业大学深圳研究生院;
【基金】：国家自然科学基金项目(No.51469005) 广西自然科学基金项目(No.2015GXNSFAA139270,No.2015GXNSFAA139257) 广西研究生教育创新计划项目(No.YCSZ2014200)~~
【分类号】：TU446

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