坑中坑式软土基坑抗隆起稳定性分析

Heave resistant stability analysis of pit-in-pit excavations in soft clay foundation

采用强度折减有限元法,分析软黏土地基中坑中坑式基坑的内坑开挖对外坑抗隆起稳定性的影响。随着基坑开挖,塑性应变区出现在外坑墙脚和内坑坑底,逐渐扩张至贯通,在内坑距离外坑挡墙较近的一侧形成近似圆弧状的剪切破坏面。坑外土沿着破坏面发生塑性流动,最终导致隆起破坏。研究内外坑的间距和内坑的尺寸对坑中坑式基坑的抗隆起稳定性的影响,发现增大内外坑的间距,内坑的深度以及内坑的宽度会改变破坏面的形式以及坑中坑式基坑的抗隆起稳定安全系数的大小。归纳得出在3种参数影响下总共存在3种不同的破坏面形式。

The finite element method with the strength reduction technique was adopted to analyze the effects ning wall of the outer pit. The plastic flow of soil outside the pit along the failure surface resulted in heaves. Effects of the spacing between the outer and inner pits and the size of inner pits on the heave-resistant stability of the base pits of pit-in-pit were researched. Results show that increasing the spacing between inner and outer pits, the depth and width of inner wits will change the form of the failure surface and the safety factor of the base pit. There are three modes of failure surfaces under the effects of three kinds of parameters.