基于块体剪流组合机构的黏土基坑抗隆起稳定性分析  

Analysis of basal heave stability of braced excavations in clay based on combined mechanisms of rigid blocks and continuous velocity field

作　　者：谭廷震 黄茂松[1,2] 刘奕晖 王浩然 张中杰 TAN Ting-zhen;HUANG Mao-song;LIU Yi-hui;WANG Hao-ran;ZHANG Zhong-jie(Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University,Shanghai 200092,China;Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China;Shanghai Urban Construction Design and Research Institute(Group)Co.,Ltd.,Shanghai 200125,China)

机构地区：[1]同济大学岩土及地下工程教育部重点实验室,上海200092 [2]同济大学地下建筑与工程系,上海200092 [3]上海市城市建设设计研究总院(集团)有限公司,上海200125

出　　处：《岩土力学》2022年第4期909-917,931,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金重点项目(No.51738010);国家重点研发计划项目(No.2016YFC0800200)。

摘　　要：现行规范中基坑抗隆起稳定性计算方法主要为基于极限平衡理论的圆弧滑动法,这种方法没有严格的理论基础,得到的安全系数普遍偏高,且当挡墙插入比较小时,安全系数明显不合理。极限分析法拥有严格的理论基础,已经建立了一些基坑抗隆起稳定分析上限机构,但是这些机构的适用性缺乏一定的研究。针对上述问题,首先介绍了基坑抗隆起稳定上限分析的理论框架,对机构优化概念与块体剪流组合机构的构造做了比较全面的探讨;随后在均质地基下利用弹塑性有限元的模拟结果进行了讨论,并在非均质地基条件下利用圆弧滑动法的计算结果进行了讨论;最后总结了不同块体剪流组合上限机构的适用条件。分析表明,挡墙刚度较大且插入比较小时,应该将挡墙刚度按无穷大处理;挡墙刚度较小且插入比较大时,应该考虑挡墙刚度的影响。通过工程案例分析,验证了提出的圆弧机构上限法的合理性。In existing norms,the method for basal heave stability analysis of excavations is mainly the circular sliding method.This method bases on the limit equilibrium theory and has no rigorous theoretical basis.The safety factors derived by the circular sliding method are generally overestimated,and the derived safety factors are highly deviant when the wall embedment depth ratios are relatively small.The limit analysis method has a rigorous theoretical basis,based on which some failure mechanisms have already been proposed.However,there is a lack of research on the applicability of these mechanisms.In this study,the theoretical framework of the upper bound analysis for basal heave stability analysis is introduced,and the concept of mechanism optimization as well as the combined mechanism of rigid blocks and continuous velocity field are discussed comprehensively.The upper bound mechanisms are compared with the elastoplastic finite element method in uniform clay ground and the circular sliding method in non-uniform clay ground respectively.The applicable conditions of these mechanisms are concluded.The results show that the stiffness of the wall should be treated as infinity when the stiffness is large and the embedded depth ratio is relatively small,while the influence of the stiffness should be considered when the stiffness is small and the embedded depth ratio is relatively large.The proposed circular upper bound mechanism is verified by a field case study.

关 键 词：基坑 极限分析法 抗隆起稳定 挡墙刚度 圆弧滑动法 

分 类 号：TU442[建筑科学—岩土工程]