考虑固结影响的桩筏-地基共同作用弹塑性分析

Elasto-plastic numerical analysis of piled raft-foundation interaction considering consolidation effect of subsoils

为深入探讨桩筏基础的工作机理及其与地基的共同作用效应,应用Biot固结理论与有限元法,对于地基土采用基于Mohr-Coulomb破坏准则的理想弹塑性模型,对桩筏基础与地基共同作用问题进行了弹塑性耦合固结有限元数值分析.计算表明地基固结作用对桩筏基础-地基共同作用体系的受力变形特性具有显著的影响,桩筏基础的受力变形特性的时间变化特征依赖于下卧土层中超孔隙水压力的变化特征和桩基长度等基础特性,并随着时间的发展而最终达到稳定状态.因此,在桩筏基础上结构的工程设计中应合理地考虑地基固结效应.

To intensively discuss the loading mechanism and the interactive behavior of piled rafts with subsoil, numerical analyses on performance of an interaction system of piled rafts and the soil were conducted by using a fully coupled finite-element method based on Bolt＇ s equations of consolidation, in which the perfect elasto-ptastic constitutive model based on Mohr-Coulomb＇ s yield criterion was adopted. It is shown that the consolidation behavior of the foundation remarkably affects the time-dependent performance of interaction of piled rafts and the soil, and characteristics of the variation of excess pore pressures with time and foundation properties such as piles＇ length are intimately associated with those of the internal forces and deformations of piled raft foundation especially in poor drainage condition. It is demonstrated that the interaction analyses con- sidering the consolidation effect can give a more rational evaluation of overall performance of the system of piled rafts and soil in the design of structures on piled raft foundation.