开挖卸荷对既有群桩竖向承载性状的影响分析

发布时间：2018-10-15 21:16

【摘要】：既有建筑下增层开挖对已有桩基础的影响不同于基坑开挖对坑内桩基的影响。基于工程实例验证的有限元参数,用硬化土弹塑性模型模拟土体,用接触面单元模拟桩土相互作用,建立了桩筏基础-地基-增层开挖三维有限元模型,对增层开挖后群桩基础的竖向承载性状进行研究。分析了桩顶刚度、桩身轴力、桩侧摩阻力、桩端阻比以及土体回弹的变化规律,并研究了不同桩端土体刚度和增层开挖深度对这些参数的影响。结果表明,增层开挖后群桩中不同基桩表现出不同的承载性状,增大桩端土体刚度可明显提高单桩承载力和端阻比临界值;随着增层开挖深度的增加,侧阻和端阻的发挥程度也随之提高。研究结果有望为地下室增层开挖施工中的结构托换变形控制和补桩设计提供依据。
[Abstract]:The influence of excavation on the existing pile foundation is different from the influence of excavation on the pile foundation in the pit. Based on the finite element parameters verified by engineering examples, a three-dimensional finite element model of pile-raft foundation-soil-increasing excavation is established by simulating soil mass with the elastoplastic model of hardened soil and pile-soil interaction with contact surface element. The vertical bearing behavior of pile group foundation after excavation is studied. The variation law of pile top stiffness, pile axial force, pile side friction, pile tip resistance ratio and soil springback are analyzed, and the effects of different pile end soil stiffness and excavation depth on these parameters are studied. The results show that different piles in pile group show different bearing behavior after excavation, and the increase of soil stiffness at the end of pile can obviously increase the critical value of bearing capacity and end resistance ratio of single pile, and with the increase of excavation depth, the load capacity of single pile and the critical value of end resistance ratio can be obviously increased with the increase of pile end soil stiffness. The exertion degree of side resistance and end resistance is also increased. The research results are expected to provide the basis for the deformation control of structural underpinning and the design of pile filling in the excavation of the basement.
【作者单位】：浙江大学滨海和城市岩土工程研究中心;浙江大学软弱土与环境土工教育部重点实验室;浙江理工大学建筑工程学院;
【基金】：国家自然科学基金项目(No.41102179) 浙江省科技厅公益技术研究项目(No.2012C23029)
【分类号】：TU473.1

【相似文献】