井筒式超深地下立体车库结构计算方法研究

Study on calculation method of ultra-deep underground shaft-type stereo garage structure

井筒式地下立体车库占地面积小、开挖深度大、停车数量多,适用于解决老旧城区停车难。首先在介绍先后建成的3个工程案例的结构形式和监测数据后,总结超深地下立体车库结构计算的主要问题;然后以开挖深度为46.2m的杭州景芳园项目为例,分别利用三维连续介质有限元方法建立的地基-结构模型和结构-荷载模型,分析空间效应对结构的影响;最后以监测数据为参照,通过对比不同插入深度地下连续墙的内力和变形,分析有限元法和弹性支点法的计算精度。分析结果表明:井筒式地下立体车库结构可综合沉井和明挖地下室的做法,结合地下水处理和结构内力变形,选择合适的支护结构插入深度;对地下连续墙墙身最大弯矩和最大水平位移而言,三维有限元计算值是实测值的1.25倍以上,弹性支点法计算值是实测值的2倍左右。

The underground shaft-type stereo garage has the obvious characteristics of small plane area,large excavation depth and large number of parking,which was helpful to solve the problem of parking difficulty in old residential areas and downtown areas.Firstly,after introducing the structural types and monitoring data of three engineering cases completed successively,the main problems in the calculation of ultra-deep underground stereo garage structure were summarized.Then,taking Hangzhou Jingfangyuan project with excavation depth of 46.2 m as study background,the foundation-structure model and the structure-load model established by the three-dimensional continuum finite element method were respectively used to analyze the influence of the space effect on the structure.Finally,using the monitoring data as a reference,the calculation accuracy of the finite element method and the elastic fulcrum method were analyzed by comparing the internal force and deformation of the underground diaphragm wall with different insertion depths.The analysis results showed that underground shaft-type stereo garage structure should integrate with the practice of caisson and open excavation basement to select the appropriate excavation method and insertion depth of retaining structure by combined with groundwater treatment and structural stress and deformation.For the maximum bending moment and maximum horizontal displacement of underground diaphragm wall,the calculation value of the three-dimensional finite element was more than 1.25 times of the measured value,and the calculation value of the elastic fulcrum method was about 2 times of the measured value.