岩溶隧道施工围岩变形动态监测与仿真分析

 岩溶区隧道因受岩溶发育程度、岩溶位置等影响，其围岩位移特征与一般隧道存在较大区别。以达成高速铁路宝石岩隧道为工程背景，对侧部含有溶洞的隧道围岩变形进行现场监测研究，并运用有限差分软件FLAC3D进行仿真分析，现场监测和仿真分析所得围岩变形规律基本一致。结果表明：隧道开挖后，围岩分别向溶洞和隧道内变形，溶洞与隧道之间的围岩向两个相反的方向变形，是较危险区域；靠近溶洞的隧道左侧特征位置的位移值要比远离溶洞的隧道右侧相应部位的位移值大，其中，左边墙的水平位移是右边墙的2倍左右。随着开挖断面处溶洞尺寸的逐渐增大，拱顶下沉位移增量最大，边墙水平位移增量次之，腰拱水平位移增量最小。溶洞顶部下沉位移和靠近隧道的溶洞右侧部水平位移较大，溶洞其他部位的位移值较小。侧部含有溶洞的隧道，其围岩变形的非对称性容易使隧道受“偏压”。所得结论可为同类隧道的设计、施工和研究提供有益的借鉴和参考。

DYNAMIC MONITORING AND SIMULATION ANALYSIS OF SURROUNDING ROCK DEFORMATION OF TUNNEL IN KARST REGION

Because of the influence of karst caves，deformation characteristics of surrounding rock of tunnel in karst zone are different from those of common tunnel. Taking Baoshiyan tunnel in Dacheng high-speed railway as an example，the deformation characteristics of surrounding rock of the tunnel with a karst cave at side is studied by field monitoring and by finite difference software ，and the deformation characteristics of the surrounding rock of tunnel are obtained by field monitoring and by simulation analysis，which are mostly consistent. Results indicate that after the tunnel is excavated，the surrounding rock moves toward the karst cave and the tunnel. The surrounding rock between the karst cave and the tunnel deforms in opposite direction，and it is also the most dangerous zone. The displacements of the surrounding rock of the tunnel¢s representive positions near the karst cave are larger than those positions away from the karst cave，and the horizontal displacement of the left side wall is twice bigger than that of the right side wall. With the increase of the karst cave dimension，the settlement increment of the crown is the largest，and the horizontal displacement increment of the side wall is moderate and that of the hance is the least. The subsidence of the karst cave top and the horizontal displacement at the right position are larger，and those of other positions are little. Because the deformation of the surrounding rock of the tunnel appears unsymmetrical，deviation pressure will occur during excavation. The conclusion can be useful in design，construction and research of similar tunnels.