近断层掘进的煤层瓦斯赋存及突出危险性

Coal seam gas occurrence and outburst dangerous in near-fault excavation

采用RFPA;数值软件模拟了煤与瓦斯突出的发生过程,研究了从断层下方(上、下盘)和煤层同一水平(上、下盘)进行掘进的两种情况。通过研究分析,突出未发生前,随巷道向前掘进,断层区域出现应力集中增大并发生破坏。断层破坏后,煤层受到拉、剪应力的共同作用也发生破坏,煤层瓦斯解析。由于应力和瓦斯压力的平衡被打破在瞬间发生了突出情况。若沿断层上盘掘进,过断层后,巷道上方煤层发生破坏,煤体发生的破坏更严重,随着巷道在煤层的掘进,上部煤层受力增大,引起断层上盘的破坏,进而发生更加严重的突出。而沿断层下盘掘进,煤体的破坏较少,当巷道掘进至断层附近时,瓦斯压力使破碎的煤块沿着断层破裂面压入掘进巷道进而发生煤与瓦斯突出。

The occurrence process of coal and gas outburst is simulated by RFPA;numerical software, and two cases of tunneling from below the fault(hanging wall and footwall)and the same level of coal seam(hanging wall and footwall)are studied.The analysis shows that before the outburst occurs, the stress concentration increases and damage occurs in the fault area with the advance of the roadway;after the fault is destroyed, the coal seam is also destroyed by the combined action of tensile and shear stress, and the gas desorption in the coal seam is happened;as the balance between stress and gas pressure was broken, outburst occurred in an instant.If tunneling along the hanging wall of the fault, after passing through the fault, the coal seam above the roadway will be damaged, and the damage of the coal body will be more serious.When tunneling in the coal seam, the stress of the upper coal seam will increase, causing the damage of the hanging wall of the fault, and then more serious outburst.If tunneling along the footwall of the fault, when the tunnel is excavated near the fault, the gas pressure will press the broken coal into the roadway along the fault fracture surface, and then coal and gas outburst will occur.