近接溶洞条件下隧道施工掌子面变形破坏特征数值分析

Numerical Analysis on the Features of Deformation and Damage of Tunnel Face in the Course of Construction under the Condition of Coming Close to Karst Cave

以宜万铁路齐岳山隧道工程为背景,以危险地段的岩溶地质条件为基础,应用三维有限元分析方法,在隧道掌子面前方的溶洞规模大于、等于和小于隧道掌子面规模的3种情况下,模拟分析不同岩体厚度、不同岩溶水压力时隧道掌子面的变形破坏规律。研究结果表明:当溶洞直径大于或等于隧道直径时,相同岩溶水压力作用下掌子面变形值相近,当溶洞直径小于隧道直径时,掌子面变形量小;掌子面变形量最大值出现在掌子面中心位置;当掌子面与岩溶洞壁之间的距离大于2.0 m时,掌子面变形量增加并不明显;在溶洞内无水压力条件下,掌子面岩体塑性区范围很小,但随着水压力的增大,塑性区的范围逐步增大。

Qiyueshan tunnel engineering of Yichang-Wanzhou Railway was taken as the research background.Based on the karst geological conditions in hazardous section,3D finite element analysis method was applied to simulate and analyze the deformation and damage law of the tunnel face with different rock mass thickness and different karst water pressure under three conditions,namely,the scale of the karst cave in front of the tunnel face is greater than,equal to and less than the scale of the tunnel face.The results indicate that when the diameter of the karst cave is greater than or equal to the tunnel diameter,the deformation values of the tunnel face are similar under the action of the same karst water pressure.When the diameter of the karst cave is less than the tunnel diameter,the deformation of the tunnel face is small.The maximum deformation of the tunnel face appears in the center position of the tunnel face.When the distance between the tunnel face and the wall of the karst cave is greater than 2.0 m,the increase in the deformation of the tunnel face is not obvious.Under the condition that there is no water pressure in the karst cave,the plastic area of the tunnel face rock mass is very small.However,the plastic area will gradually increase along with the increase of water pressure.