不排水双层粘性土地基极限承载力的数值分析

采用弹塑性有限元分析了条形基础作用下不排水条件的双层粘性土地基极限承载力性状。采用修正的地基承载力系数表征,并将不同的几何与土层参数条件下的数值解与上下限解和经典的经验解进行比较。表明弹塑性位移有限元法可以很好地求解地基的极限承载力问题,其求解得到的修正地基承载力系数与基于下限原理的有限元解很接近,而上限解高估了地基的极限荷载值,传统的经验解在某些条件下却偏小。

NUMERICAL ANALYSIS OF ULTIMATE BEARING CAPACITY OF UNDRAINED TWO-LAYERED CLAYS

The ultimate bearing capacity of a rigid strip footings resting on undrained two-layered clays Is estimated using an elastio-plastic finite element method. For a wide range of problem geometries, the results are obtained and presented with the terms of modified bearing capacity factor. The results are compared with those obtained from existing limit analysis, empirical and semi-empirical solutions, upper bound solutions, as well asfinite element analysis based on the upper and lower bound limit theorems. The comparisons show that the elasto-plastic displacement finite element method can give robust and accurate solutions to the true limit bearing capacity of clay profiles. And the solutions of the paper have a good agreement with the lower bound solutions. However the upper bound solutions can overestimate the bearing capacity of undrained two-layered clays in some instance. The classical empirical solutions can underestimate the collapse load.