上硬下软地基应力分布特征及计算方法研究

The Distribution Features and Computation Method of Stress in Rigid-Upper-Layer and Soft-Lower-Layer Ground

在软弱下卧层的承载力验算和沉降计算中,附加应力的确定是个难点.常用的方法是用均质土中的应力解或应力角扩散法来得到上硬下软地基的应力场,方法简单但计算结果可能存在较大误差.针对此问题,本文利用非均质弹性体内竖向应力的理论解和弹性地基梁理论来分析上硬下软双层地基分界面的应力分布特性,并结合有限元数值分析结果,提出了应力扩散系数的实用计算方法.该方法可以考虑不同位置和土层模量对应力扩散的影响,且公式形式简单,便于使用.

In the capacity and settlement computation of soft substratum,the determination of additional stress is difficult. To solve such a problem,the commonly used approach is to determine the stress field of soft substratum by using stress solution of isotropic soil or method of stress diffusion angle.This approach is simple yet likely to be erroneous in computation result.In an effort to address this issue,this paper analyzes the stress distribution characteristics of the interface of rigid-upper-layer and soft-lower-layer ground by using the knowledge of the theoretical solution of vertical stress in heterogeneous elastic body and elastic ground beam theory.A practical computation method of stress diffusion coefficient is put forward based on finite element numerical analysis results.This method takes account of the influences of different locations and soil modulus.Moreover,its formula is simple in form and easy to use.