考虑主应力轴旋转的基坑开挖应力路径研究  

Research on stress path during excavation considering rotation of principal stress axis

作　　者：应宏伟[1,2] 李晶[1,2] 谢新宇[3] 朱凯[1,2] 周建[1,2] 

机构地区：[1]浙江大学软弱土与环境土工教育部重点实验室,杭州310058 [2]浙江大学岩土工程研究所,杭州310058 [3]浙江大学宁波理工学院,浙江宁波315100

出　　处：《岩土力学》2012年第4期1013-1017,共5页Rock and Soil Mechanics

基　　金："十一五"国家科技支撑计划项目(No.2008BAJ06B01-4);宁波市科技创新团队基金(No.2011B81005)

摘　　要：首先对应力路径的概念进行丰富和扩展,提出考虑主应力轴旋转的三维应力路径,然后采用数值方法,对基坑开挖过程中的应力路径进行了深入分析,研究了基坑内外各种应力路径及其规律,结果表明:开挖过程中无论横向还是竖向,应力路径都表现出卸荷特性,且坑内卸荷量大于坑外卸荷量,使得坑内应力变化及主应力轴旋转较坑外大;随着离基坑中心距离的增大,坑内应力变化减小,主应力轴旋转趋缓;开挖过程对坑外应力变化及主应力轴旋转的影响随离围护墙距离的增大而减小。坑内应力路径总体表现为平均压应力p减小,广义剪应力q减小,主应力轴偏转角增大;坑外应力路径总体表现为p减小,q增大,增大。最后归纳出基坑开挖过程中坑内与坑外的典型应力路径,以指导基坑工程实践设计分析和室内试验模拟。Firstly, the concept of stress path is extended by proposing the threedimensional stress path considering the rotation of principal stress axis. Then the deep analysis of the stress path during excavation is carried out by numerical method. It is shown that whether the horizontal or the vertical stress exhibits characters of unloading during excavation; and the magnitude of unloading of the inner part of foundation pit is larger than that of the outer part of foundation pit, which cause the changes of both stress and rotation of principal stress axis of the inner part of foundation pit are larger than that of the outer part of foundation pit. As the distance from the centre of foundation pit increasing, both the changes of stress and rotation of principal stress axis of the inner part of foundation pit decrease. The effects of excavation on the change of stress and the rotation of principal stress axis of the outer part of foundation pit decrease as the distance from the wall increasing. The main performance of the stress path of the inner part of foundation pit is that the mean compressive stress p and the generalized shear stress q decrease while the rotation angle of principal stress axis tr increases. And the main performance of the stress path of the outer part of foundation pit is that q and a increase while p decreases. So on the basis of the main performance of the stress path, the typical stress paths of both inner and outer parts of foundation pit during excavation are obtained to guide the practice design analysis and indoor experiment of foundation pit engineering.

关 键 词：基坑开挖 应力路径 主应力轴旋转 应力变化 

分 类 号：TU431[建筑科学—岩土工程]