下伏溶洞对穿越上砂下黏地层隧道管片变形影响分析

Analysis of the Influence of the Underlying Karst Cave on the Deformation of the Tunnel Tube Going Through Upper Sand Lower Clay Stratum

以武汉地铁6号线Ⅱ标段"前马区间"为工程背景,针对其上砂下黏且下伏灰岩溶洞发育的地质条件,运用有限差分软件FLAC3D 5.0建立三维数值分析模型,在考虑流固耦合效应的基础上,研究下伏溶洞对穿越上砂下黏地层盾构隧道管片变形的影响。针对不同的溶洞距基岩面距离d、溶洞直径D、跨度w、溶洞充填率ω,分析隧道管片水平及竖直方向变形。结果表明:溶洞距基岩面距离d越大、溶洞直径D越小、跨度w越小、溶洞充填率ω越大,隧道管片的变形越接近无溶洞情况;下伏溶洞的存在一定程度上抑制管片的水平位移收敛变形;ω从0.75增大到1.00时,管片竖向变形大幅度减小,进行溶洞处理时需充分注浆。

This paper regards the"front horse section"of section Ⅱ of Wuhan Subway line 6 as the engineering background.According to the geological conditions of upper sand lower clay and development karst cave in underlying limestone,this paper uses finite difference software FLAC3D 5.0 to establish the three-dimensional numerical analysis model.On the basis of considering the fluid-solid coupling effect, the influence of the underlying karst cave on the deformation of the shield tunnel tube going through upper sand lower clay stratum is studied.For different distances from karst cave to bedrock surface,diameter and filling rate of karst cave,this paper analyzes the horizontal and vertical deformation of the tunnel tube.The results show that the distance from karst cave to bedrock surface is greater,the karst cave's diameter is smaller,the karst cave's span is smaller and the karst cave's filling rate is greater,the deformation of tunnel tube is closer to insoluble hole.The exist of the underlying karst cave is inhibited to the horizontal displacement convergent deformation of the tube to a certain extent.When the filling ratio of karst cave increases from 0.75 to 1.00,the vertical deformation of the tube is greatly reduced,it suggests that sufficient grouting is required for cavern treatment.