考虑覆盖层对地基应力分散效应的地基沉降计算方法探讨

An Evaluation Approach of Final Settlement for Foundation via Considering Stress Dispersion Effect due to Existence of Top Crust

对于软土地基上的建筑物的沉降计算,我国规范推荐采用分层总和法。分层总和法中地基附加应力的计算以点荷载作用下的半无限空间的Boussinesq解为基础。对于具有不同刚度和强度相差较大的地层而言,以此方法为基础计算得到的最终沉降往往偏大。本文提出一种基于多层弹性理论的考虑覆盖层对地基应力分散作用的地基沉降计算方法。这种方法的计算结果使地基中的应力水平较基于Boussinesq解的结果大幅降低,对于某工程实例而言,计算得到的地基中的总有效应力小于前期固结压力,土层的变形相对较小。工程实测的结果表明,所提出方法计算结果与实测结果较为接近。

Layer-wise summation method is recommended to calculate final settlement of buildings on soft subsoil.The calculation of additional stress in soft subsoil is generally based on Boussinesq＇s theory.However,the calculated final settlement is larger than the measured value for most soil layers,especial for the layered subsoil with different stiffnesses and strengths.This paper present an approach to calculate the final settlement of building via considering the stress dispersion effect of top crust based on layered elastic theory.The calculated stress based on layered elastic theory is greatly less than that based on Boussinesq＇s theory.The soil deformation is relatively smaller because the stress calculated by layered elastic theory is less than the pre-consolidation pressure.The aforementioned method is used in a case study.The result indicates that the calculated final settlement based on the proposed approach is close to the measured value.