不排水双层粘土地基承载力的强度折减有限元分析

地基极限承载力的理论计算公式只适用于均质土地基,对于两层土强度参数较为悬殊的层状地基的极限承载力,用有限元法计算更为准确和合理.强度折减有限元法是一个计算安全系数可靠的方法,利用这一原理,采用有限元岩土软件Plaxis8.2建立计算模型,先计算单层土的极限承载力,计算结果与Prandtl解比较,误差极小,在精度满足要求的基础上计算不排水条件下双层粘性土地基的极限承载力.经过计算结果的对比,分析上层土厚度和下层土强度对极限承载力的影响.

Numerical analysis for bearing capacity of undrained two-layer clays by FEM with strength reduction

Classical theory formulae of ultimate bearing capacity are considered only applicable to homogeneous ground.For nonhomogeneous ground of two-layer soils,there is a more reasonable and rigorous method based on finite element method with strength reduction.Plaxis8.2,a finite element software for geotechnical engineering,is able to calculate safety factor of foundations by finite element method with strength reduction.By comparing to Prandtl's solution,the precision of plaxis is considered well satisfying.Then plaxis was used to building the model of undrained two-layer soils clays and educed ultimate bearing capacity which is related to the thickness of upper layer and the strength of sublayer.Based on the results,the influence factor and characteristic of ultimate bearing capacity were analysed in detail.