开挖对工程桩的影响规律分析
Effect of excavation on piles
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摘要: ABAQUS软件中的临界状态模型可以较好地反映正常固结黏土的应力应变特性,借助ABAQUS建立了三维数值模型,研究正常固结黏土中基坑开挖卸载对已施做工程桩的影响规律。给出了ABAQUS临界状态模型中参数与室内土工试验参数的关系。为验证模拟结果的合理性,首先对由子程序产生的初始孔隙比以及基坑变形结果进行了检验。根据计算结果,探讨了工程桩桩身轴力随开挖的变化、开挖完成后的桩身轴力分布规律、开挖完成后桩身弯矩的分布规律以及影响开挖卸载所诱发的桩身内力分布规律的因素,以期对今后类似工程的设计和施工提供借鉴。Abstract: ABAQUS is a popular commercial finite element software and the clay plasticity model presented in it can perfectly simulate the stress-strain behavior of the normally consolidated clay. A three-dimensional finite model is established in ABAQUS to study the deep excavation effect on the underpinning piles which are constructed before the soil excavation. The parameters employed by the porous elasticity model and the critical state plasticity model in ABAQUS are decided according to the triaxial compression tests or oedometer tests. To verify the numerical simulation results, the initial void ratio obtained from the programmed subroutine and the deformations due to the soil excavation are analyzed. The variation of the axial forces with the soil excavation is presented. The distribution of the axial forces and bending moments for the piles at different locations can be obtained from the numerical simulation results. The regularities of distribution for the forces and moments are discussed and the influence factors are also mentioned. The results obtained here can be referred for similar practices.