保护层开采上覆煤层变形特性数值模拟

Numerical simulation of the upper coal and rock deformation characteristic caused by mining protecting stratum

基于岩石破裂损伤理论和有限元计算方法,利用RFPA应用系统模拟分析了保护层开采过程中,被保护层层厚变形规律、煤层水平变形特征和保护层与被保护层之间的相对层间距对被保护层保护效果的影响,认为随着保护层采煤工作面向前推进,被保护层垂直变形呈现"M"型分布;卸压区煤层水平变形呈现拉抻和挤压状态,增加该区域煤体机械破坏,有利于被保护层次生裂隙的发育;相对层间距对被保护层卸压变形产生较大影响,相对层间距愈大,其变形量减小,不利于煤层离层裂隙和破断裂隙的产生.对数值模拟结果与现场实际测定结果进行对比分析,两者基本吻合.

According to the rock failure damage theories and the finite element method, the dynamic progressive process of the upper protected coal caused by mining the protecting coal was simulated by RFPA soft system. The deformation law of the protected coal thickness, the horizontal movement characteristics and the effects of the relative distance for the protected strata along with the mining protecting stratum mining were found. The results indicate that the vertical deformation of the protected coal strata is distributed according to ＂M＂ within limits of protected strata, and the coal seams in pressure relief zone of protected layer horizontally move at reverse orientation, which makes the coal seam endure the level stretch and extrusion and results in physical disturbance of the coal body in the area that makes for the development of secondary fracture, and through simulating the connection between the relative distance and the pressure relief deformation of protected layer, it is observed that the longer the relatively interlayer interval, the smaller the deformation is, which goes against the creation of rupture crannies and bed separation crannies. The experiment results at site are consistent with those results shown above.