地基承载力尺寸效应离散元分析

Analysis on Scale Effect of Bearing Capacity of Foundation by Discrete Element Method

摘要:

采用离散元软件PFC2D模拟4种宽度的载荷试验，并结合前人试验结果，研究地基尺寸效应的一般规律，探讨尺寸效应产生的原因.结果表明：承载力系数随基础宽度的增大而减小，减小量随基础宽度的增大而降低.p s曲线的最大曲率（即拐点的曲率）随基础宽度的增大而减小，曲线总体形态逐渐趋于平滑.净砂在离散元模拟中, 它的强度包线为一条直线.随着应力水平的提高，土颗粒的峰值内摩擦角基本不变，但是地基极限承载力依然存在尺寸效应，这说明强度包线的非线性并不是尺寸效应产生的根本原因.

关键词:地基承载力; 承载力系数; 尺寸效应; 强度包线

Abstract:

Based on the previous experimental results and a simulation loading test with 4 widths of the footing by employing the discrete element software of PFC2D, a study was made on the general law of scale effect and the causes of the scale effect. The result indicates that with the increasing of the width of the footing, bearing capacity factor decreases, and the amount of reduction decreases with the increasing of the width of the footing. Maximum curvature of p s curve (i.e., the curvature of the inflection point) decreases with the increasing of the width of the footing, and the overall shape of p s curve gradually gets smooth. In the discrete element method(DEM) simulation of net sand, the soil strength envelope is a straight line. When peak internal friction angle of particles remains as a constant with an increasing confining pressure, the scale effect remains on the bearing capacity of the foundation, which suggests that the strength envelope of nonlinear is not the fundamental cause of scale effect.

Key words:foundation bearing capacity; bearing capacity factor; scale effect; strength envelope