保护煤层开采引起覆岩垮落及其被保护煤层透气性变化的数值模拟

NUMERICAL SIMULATION OF STRATUM COLLAPSE AND GAS PERMEABILITY EVOLUTION FOR THE PROTECTED COALSEAM INDUCED BY EXCAVATION

在充分考虑到岩石的非均匀性、存在的节理、裂隙等基础上，运用岩石破裂过程分析系统（RFPA），进行由于深部煤层（保护层）开采诱发的上覆岩层垮落过程及被保护煤层透气性系数变化的数值模拟。模拟结果较好地展示在开采保护煤层过程中覆岩节理、裂隙的发育、顶板的垮落以及被保护煤层的弯曲、变形和透气性系数的变化过程，反映出岩层移动的三带特征：垮落带、断裂带、整体弯曲下沉带以及这三带演化的动态过程。从破坏点空间分布中可以看出岩层破坏的逐层传递性。文中阐明被保护煤层在保护煤层开采期间的应力场与透气性变化之间的联系。

With the full consideration of the heterogeneity, existing joints, and cracks in the rock, a numerical approach of rock failure process analysis（RFPA） to simulate the stratum movement, layer separation, the whole collapse progresses, and gas permeability changing of the protected coalseam induced by deeper excavation is proposed. The numerical simulation results well displayed the whole processes of the growth of the joint, crack of the stratum and the bending, displacement, and the change of gas permeability for the protected coalseam during the deeper coalseam excavation. It also disclosed the three phases of the stratum movement, i.e., collapse area, rupture area, and whole sunk area. It can be seen from the distribution of acoustic emission in the space that the stratum failure is transferred from deeper to surface. By the analysis of the stress fields changing, the reasons of the gas permeability improvement of the protected coalseam are presented.