软岩铁路隧道支护受力及优化分析

以玉磨铁路曼么二号隧道为背景,分析软岩隧道受力特征,以及施作临时仰拱对隧道围岩压力、位移的影响,为以后的工程方案比选提供参考。通过采用数值模拟和现场监测实际数据对比分析的方法,分析了三维隧道围岩、钢拱架的真实受力状态,模拟了有无临时仰拱时隧道的围岩压力和位移变化情况;探讨在软弱围岩地质情况下,有无临时仰拱对隧道应力场和位移场的影响,得出了施作临时仰拱对控制软弱围岩隧道的变形效果比较明显。结果表明:钢拱架右侧受力明显大于左侧,玉磨铁路曼么二号隧道受力不对称,可能存在偏压现象;实测数据与模拟数值变化趋势基本相同,验证了MIDAS/GTS能够有效地模拟隧道施工过程;通过模拟对比分析,施作临时仰拱时拱顶沉降值减小了15.5%,左拱腰位移减小了69%,右拱腰位移减小了66.7%,隧道围岩压力最大值为143.4 kPa,出现在拱顶位置,最大围岩压力减小了6.5%。

Stress and Optimization Analysis of Soft Rock Railway Tunnel Support

The purpose of the study is to analyze the stress characteristics of the soft rock tunnel and the effect of the temporary inverted arch on the surrounding rock pressure and displacement of the tunnel in the Yumo No. 2 tunnel of Yumao Railway, and provide reference for the subsequent comparison of engineering schemes. Method of study: A method of comparative analysis using actual data by numerical simulation and on-site monitoring. The true stress state of the surrounding rock and steel arch of the three-dimensional tunnel is analyzed. The variation of surrounding rock pressure and displacement of the tunnel with or without temporary inversion is simulated. The influence of the temporary invert arch on the stress field and displacement field of the tunnel under the condition of weak surrounding rock geological conditions is discussed. It is concluded that the deformation effect of the temporary invert arch is small for controlling the soft surrounding rock tunnel. Research results: the right side of the steel arch is significantly more stressed than the left side, the tunnel is asymmetrical, and there is a possibility of bias. The measured data and the simulated value change trend are basically the same, which verifies that MIDAS/GTSNX can effectively simulate the tunnel construction process. Through simulation and comparison analysis, the settlement value of the vault is reduced by 15.5% when the temporary invert is applied; the displacement of the left arch is reduced by 69%; the displacement of the right arch is reduced by 66.7%, and the maximum pressure of the surrounding rock of the tunnel is 143.4kPa. , appearing in the vault position, the maximum surrounding rock pressure is reduced by 6.5%.