坑中坑开挖影响下的基坑稳定性研究  

Foundation Pit Stability Under the Influence of the Pit in Pit Excavation

作　　者：杨才 王世君[1] 丰土根 YANG Cai;WANG Shijun;FENG Tugen(Guangzhou Metro Design and Research Institute Co.,Ltd.,Guangzhou,Guangdong 510010,China;Research Institute of Geotechnical Engineering,Hohai University,Nanjing,Jiangsu 210098,China)

机构地区：[1]广州地铁设计研究院股份有限公司,广东广州510010 [2]河海大学岩土工程研究所,江苏南京210098

出　　处：《水利与建筑工程学报》2019年第2期52-55,67,共5页Journal of Water Resources and Architectural Engineering

基　　金：国家自然科学基金项目(51009054)

摘　　要：坑中坑开挖对于悬臂式支护结构基坑稳定系统有诸多影响,内坑的开挖会引起基坑被动区土体抗力损失,增大坑外土体的剪切变形趋势,降低基坑整体稳定性。采用强度折减有限元法,对坑中坑的三个主要影响因素:坑址系数、深度比、面积比进行了控制变量研究,研究表明:对比三种失稳判据下的稳定安全系数,基坑整体稳定安全系数与坑趾系数呈正相关关系,与深度比和面积比呈负相关关系,据此建议在内坑开挖过程中,要尽量避免内坑紧邻外坑坑壁开挖、内坑过度深挖、内坑面积过大开挖。Pit in pit excavation has many effects to the cantilever retaining structure foundation pit’s stability system.Pit in pit excavation will cause the loss of soil’s resistance in passive zone,and increase the trend of soil’s shear deformation,at the same time reduce the overall stability of foundation pit.In this paper,by using strength reduction finite element method,three main factors of pit in pit pit site coefficient,depth ratio,area ratio were analyzed.Research results shows that:comparing the stability safety factor under three kinds of instability criterion,this paper suggests using the run through of plastic zone optimization criterion.The stability safety factor of foundation pit is positively related to pit toe coefficient,and is negatively related to the depth ratio and area ratio.Therefore,in the process of pit excavation,pit in pit’s excavation being adjacent to the outer wall,excessive digging and the size being too large should be avoided.

关 键 词：坑中坑 强度折减法 稳定性 失稳判据 

分 类 号：TU931[建筑科学—结构工程]