各向异性软土深基坑坑底抗隆起稳定性分析

孔德森^{1, 2}，门燕青^{1, 3}，王丽华^{1, 2}，张秋华^{1, 2}

(1. 山东科技大学 土木建筑学院，山东 青岛，266590；
2. 山东科技大学 山东省土木工程防灾减灾重点实验室，山东 青岛，266590；
3. 同济大学 土木工程学院，上海，200092)

摘 要：基于软土深基坑极易发生坑底隆起破坏的现状，采用Casagrande各向异性强度理论，利用极限平衡方法，针对圆弧滑动破坏模式，考虑土体各向异性特征，推导软土深基坑坑底抗隆起稳定性的分析公式。同时，对推导所得的公式进行基坑开挖空间效应和时间效应修正，在此基础上，结合典型的基坑坑底隆起破坏实例对推导所得的坑底抗隆起稳定性分析公式进行对比分析和验证。研究结果表明：同时考虑土体各向异性和基坑开挖时空效应的坑底抗隆起稳定性分析公式更加合理，对软土深基坑工程的设计和分析具有借鉴和参考价值。

关键词：基坑；隆起；稳定性；各向异性

Basal heave stability analysis of deep foundation pits in anisotropic soft clays

KONG De-sen^{1, 2}, MEN Yan-qing^{1, 3}, WANG Li-hua^{1, 2}, ZHANG Qiu-hua^{1, 2}

(1. College of Civil Engineering and Architecture, Shandong University of Science and Technology,
Qingdao 266590, China;
2. Shandong Provincial Key Laboratory of Civil Engineering Disaster Prevention and Mitigation,
Shandong University of Science and Technology, Qingdao 266590, China;
3. College of Civil Engineering, Tongji University, Shanghai 200092, China)

Abstract:Based on the situation of deep foundation pits in soft clays that basal heave failure occurs easily, Casagrande anisotropy strength theory and limit equilibrium method were adopted in the derivation of the analyzing formula for the basal heave stability analysis of deep foundation pit in soft clays with soil anisotropy being considered. Meanwhile, modifications on spatial effect and time effect of the foundation pit excavation were conducted for the obtained formula. Based on the above analysis, comparison analysis and verification were carried out between the obtained formulae for the basal heave stability analysis and typical failure cases of foundation pit basal heave. Research results indicate that the analysis formula of basal heave stability deducted when soil anisotropy and spatial-time effect of the foundation pit excavation are considered, it is closer to the project practice and of certain reference value for the design and analysis of deep foundation pit project.

Key words:foundation pit; basal heave; stability; anisotropy