明挖基坑对既有下卧地铁盾构隧道影响的三维分析

Three Dimensional Analysis of the Influence of Foundation Pit Excavation on the Existing Subway Shield Tunnel

湘雅路过江通道工程明挖基坑近距离上跨长沙市轨道交通地铁1号线,为了保证施工的顺利进行,建立三维数值模型研究基坑开挖对地铁1号线的影响。根据三维计算分析可知,采用基底MJS旋喷桩注浆预加固技术对隧道周边土层进行预加固可有效减少隧道衬砌变形,相较于未采用加固方案,采用加固方案时的衬砌最大竖向位移减小了33.6%,最大径向位移减小了76.9%,结构的最大轴力减小了11.7%,最大正弯矩较减小了17.8%,最大负弯矩减小了8.2%。

The excavation foundation pit of Xiangya road river crossing project crosses Changsha Metro Line 1 in a short distance.In order to ensure the smooth construction,a three-dimensional numerical model is established to study the impact of foundation pit excavation on Metro Line 1.According to the three-dimensional calculation analysis,it can be seen that the pre-reinforcement of the soil layer around the tunnel can effectively reduce the deformation of tunnel lining by using the pre-reinforcement technology of MJS rotary jet grouting pile.Compared with that without the reinforcement scheme,the maximum vertical displacement of the lining decreases by 33.6%,the maximum radial displacement by 76.9%,the maximum axial force by 11.7%,the maximum positive moment by 17.8%,and the maximum negative moment by 8.2%.