复杂煤层组隧道围岩与支护结构施工力学行为

Construction Mechanical Behavior of Surrounding Rock and Supporting Structure of Tunnel in Complex Coal Seam Group

隧道开挖穿越倾斜煤系地层时,容易出现因围岩变形过大而导致的坍塌,严重时进而诱发瓦斯突出、爆炸等次生灾害发生。为保证富煤隧道安全高效施工,以天城坝隧道为背景工程,采用数值模拟软件FLAC^(3D)结合现场监测的方法,探究五种厚度下复杂煤层组的围岩变化规律以及施工工法的适用性。研究结果表明:①随着煤层厚度的增大,煤层组围岩变形均越来越大,变形在开挖步数50 m左右处达到峰值。②对比分析两种工法下五组煤层围岩变形量和初期支护应力,三台阶预留核心土法相较于三台阶法能有效降低围岩变形。③将三台阶预留核心土开挖模拟结果与现场实测数据对比,拱顶和仰拱数据差值率分别为5.69%和5.68%,均在允许范围内。这说明三台阶预留核心土法施工能有效控制隧道施工对洞周围岩的扰动,可保证复杂煤层组隧道的安全高效开挖。

When the tunnel is excavated through the inclined coal measure strata,it is easy to collapse due to the excessive deformation of the surrounding rock,and in severe cases,it will induce secondary disasters such as gas outbursts and explosions.To ensure the safe and efficient construction of the coal-rich tunnel,this paper takes the Tianchengba tunnel as the background project and uses the numerical analysis software FLAC^(3D) combined with the field monitoring method to explore the surrounding rock variation law of the complex coal seam group under five thicknesses and the applicability of the construction method.The results show these as follows.With the increase of the thickness of the coal seam,the deformation of the surrounding rock of the coal seam group is getting larger and larger,and the deformation reaches the peak at about 50 m of the excavation steps.Comparing and analyzing the deformation of surrounding rock and the initial support stress of five groups of coal seams under the two construction methods,the three-step reserved core soil method can effectively reduce the deformation of surrounding rock compared with the three-step method.Comparing the simulation results of three-bench reserved core soil excavation with the field-measured data,the difference rates of the vault and inverted arch data are 5.69%and 5.68%respectively,which are within the allowable range.This shows that the construction of the three-step reserved core soil method can effectively control the disturbance of the tunnel construction to the surrounding rock of the tunnel,and can ensure the safe and efficient excavation of the tunnel in the complex coal seam group.