The coal-seam gas content and pressure in the section of Tianping tunnel where the coal seam was exposed are very high, the ground stress is large and the tunnel support becomes more and more difficult. In order to smoothly and safely drive through the coal seam exposing section and control the stability of the tunnel surrounding rock, analysis was made on the deformation failure characteristics of the tunnel surrounding rock by using FLAC3D program which was computed based on the mixed discrete method, corresponding support measure and scheme were obtained through research, and site implementation and effect monitoring were carried out. The numerical simulation results showed the state of the stress redistribution and change of the tunnel, the high concentration of the stress in the local range of two sides 3 to 5 m away from the roadway wall was the most direct factor leading to roadway instability. The site monitoring results indicated that the maximum deformation of the tunnel surrounding rock was 108 mm after the support scheme was adopted and it was in an allowable range, so the roadway can keep stable for a long time.%天坪隧道平导揭煤段煤层瓦斯含量高、瓦斯压力大,尤其地应力大,巷道支护越来越困难.为了能够顺利安全通过揭煤段,控制巷道围岩的长期稳定,利用基于混合离散法计算的FLAC3 D程序计算分析巷道围岩的变形破坏特征,研究得出相应的支护对策和方案,并进行现场实施和效果监测.数值模拟结果显示了巷道应力重新分布变化的状态,两帮距离巷道壁3~5m局部范围的应力高度集中是导致巷道失稳的最直接因素. 现场监测结果表明,采用该支护方案后,巷道围岩变形量最大值108 mm,在允许范围内,能够确保巷道长期稳定.
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