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为了预测地铁深基坑开挖阶段围护结构的变形特性,从围护结构综合刚度的角度研究了软土地区地铁深基坑的围护结构设计方法。鉴于Clough综合刚度模型存在诸多缺陷,提出了新的MVSS综合刚度模型,其包含了围护墙(桩)刚度、基坑深度、支撑刚度、支撑水平及竖向间距、地基加固等多个变量,反映了基坑围护结构的整体属性。从有限元计算及地铁基坑实测变形等角度验证了MVSS综合刚度合理性,并建立了地铁深基坑围护结构侧向变形与基坑围护综合刚度之间的函数算式。该算式为基坑围护结构的变形预测提供了新的思路与方法。基坑围护结构最大侧向变形与基坑MVSS综合刚度呈递减函数关系,但当其MVSS综合刚度增大至一定程度后,其继续增大对基坑围护结构变形的进一步控制效果甚微。
In order to predict the deformation characteristics of the retaining structure during the excavation of deep foundation pit, the design method of the retaining structure for the deep foundation pit in soft soil area is studied from the perspective of the comprehensive stiffness of the retaining structure. In view of the shortcomings of the Clough synthetic stiffness model, a new MVSS synthetic stiffness model is proposed, which includes many variables such as the stiffness of retaining wall (piles), pit depth, support stiffness, support level and vertical spacing, Reflects the overall properties of the foundation pit envelope. The rationality of the integrated stiffness of MVSS is verified from the point of finite element calculation and the measured deformation of subway excavation, and the function formula between the lateral deformation of the retaining structure of deep foundation pit and the integrated stiffness of foundation pit enclosure is established. The formula provides a new idea and method for the deformation prediction of the foundation pit retaining structure. The maximum lateral deformation of the retaining structure of the foundation pit is a decreasing function with the integrated stiffness of the foundation pit. However, when the overall rigidity of the MVSS increases to a certain extent, the further increase of the control stiffness of the retaining structure will have little effect on the deformation of the retaining structure of the foundation pit .