偏压基坑工程设计、施工与受力变形特性研究进展

Review on design,construction,stress and deformation characteristics of asymmetrically loaded deep excavation

在调研国内外偏压基坑工程理论与实践研究成果的基础上,分别从偏压基坑的形成原因、设计计算方法、施工安全控制技术、围护结构受力变形特性以及施工环境效应等方面对偏压基坑工程的研究现状进行总结.通过与非偏压基坑的特性进行对比分析,给出了两者之间的差异.结果表明,偏压基坑两侧围护结构的受力变形存在明显的不对称性,偏压侧受力变形大于非偏压侧,当偏压荷载达到一定值时,基坑围护结构可能发生向非偏压侧的整体偏移;传统的基坑设计计算方法未能考虑偏压基坑两侧围护结构变形的差异以及变形控制标准的不同,其设计出的结果往往过于保守或风险较大;通过土体加固改良、增加支撑系统刚度、合理安排施工顺序、信息化监测预警等措施可以降低偏压的不利影响.

Based on the research of the theory and practice of asymmetrically-loaded deep excavation at home and abroad,this paper summarizes the research status of asymmetrically-loaded deep excavation from the aspects of the formation reasons of asymmetric load,design and calculation methods,construction safety controlling technologies,stress and deformation characteristics of retaining structure and construction-induced environmental responses.The differences between asymmetrically and symmetrically-loaded deep excavation are given by comparison.The results indicate that the stress and deformation of retaining structures on both sides of asymmetrically-loaded deep excavation are obviously asymmetric,and the stress and deform-ation on the side with higher load are larger than that on the side with lower load.When the overload on the higher load side reaches a certain degree,under the action of asymmetric load,the whole retaining structures may move to the lower load side.The traditional design and calculation methods fail to take into account the deformation differences of retaining structures on both sides of asymmetrically-loaded deep excavation and the different deformation control standards,and the design results are often too conservative or risky.The adverse effects of asymmetric load can be reduced through soil consolidation and improvement,increasing stiffness of supporting system,reasonable arrangement of construction sequence,information monitoring and early warning.