地基固结对结构-筏板-地基共同作用影响的三维数值分析

不考虑上部结构刚度影响的常规设计方法及共同作用分析的二维方法尚未真实地或全面地反映上部结构-筏板基础-地基的联合工作机理.为此,基于三维Biot固结理论,结合Mohr-Coulomb理想弹塑性模型考虑地基土的非线性特性来反映地基的固结效应,对上部结构-筏板基础-地基共同作用体系进行了三维有限元数值分析.计算与分析表明:当考虑三维空间效应时,地基的固结作用对上部结构-筏板-地基共同作用体系的承载机理与变形协调能力具有显著的影响,共同作用体系中各部分受力变形特性具有明显的时间效应,并且紧密地依赖于超孔隙水压力随时间的变化特征,同时上部结构刚度对共同作用时间效应的影响较为明显.

3-D numerical analysis for effect of subsoil consolidation on interactive behavior of superstructure-raft-foundation

Both conventional methods of structural design,which do not take into account of the stiffness of the superstructure,and two-dimensional interaction analysis cannot realistically reflect the joint load-carrying and deformation mechanisms of the interactive system and cannot accurately or completely predict variations of deformations and internal forces of both structure and raft foundation.Therefore in order to better understand long-term behavior of the interactive system,time-dependent effects of soil deformations on performance of the interaction system of rafts,foundations and superstructure is evaluated in this paper.Nonlinear deformation and strength effects of foundation soils are taken into account by using the elasto-plastic constitutive model based on Mohr-Coulomb's yield criterion while the consolidation effect of subsoil under loading is incorporated by numerically solving the coupled Biot's equations of consolidation.Numerical analysis is conducted for the structure-raft-foundation interaction system by using the finite element methods.Based on numerical analysis for a given interaction system,it is suggested that,when the 3-D spatial effect is considered,subsoil consolidation has substantial impact on the load-carrying mechanism and the deformation coordinating ability of the superstructure-raft-foundation system.Internal forces in the system obviously vary with time,relecting pore pressure causing soil deformation change with time.Moreover,the stiffness of the superstructure has significant influence on their effect on the system.