基于冻结法的复合围护墙温度及受力变形特征分析

Analysis on Temperature and Deformation Characteristics of Composite Retaining Wall Based on Freezing Method

随着城市地下空间大力发展,既有隧道与新基坑的交叉位置通常会造成地下连续墙的不连续,引起地下水渗流、挡土能力不足等问题。以上海某地铁车站深基坑开挖工程为例,基于人工冻结法构造复合围护墙,实现加固土体和防水密封的双重效果。结合有限元分析方法模拟得到隧道周边土体温度分布情况,开展现场监测研究“冻结法+地下连续墙”复合围护墙的受力和变形特征。通过计算弯矩来评价冻胀对地下连续墙的不利影响,并提出墙体抵抗负弯矩的加固要求。

With the great development of the urban underground space,the intersecting position of the existing tunnel and new foundation pit usually leads to the discontinuity of the underground diaphragm wall,which leads to problems of groundwater seepage and insufficient retaining capacity.Taking the excavation project of a deep foundation pit in a metro station of Shanghai as an example,the composite retaining wall is constructed according to the artificial freezing method in order to achieve the dual effects of soil reinforcement and waterproof sealing.Combined with the finite element analysis method,the temperature distribution of soil around the tunnel is simulated and obtained.The field monitoring is carried out to study the stress and deformation characteristics of the"freezing method+underground diaphragm wall"composite retaining wall.The adverse effect of freezing method on the underground diaphragm wall is evaluated by calculating the bending moment.And the reinforcement requirements of wall body to resist the hogging moment are put forward.