正断层附近煤的物理力学性质变化及其对矿压分布的影响

通过对正断层附近煤层显微裂隙、孔隙观测，力学性质实验和数值模拟分析，系统地揭示了正断层对煤的物理力学性质和矿压分布的影响。研究表明，正断层带附近煤岩体破碎，煤（岩）体中裂隙的发育程度随距断层面距离的变小而增强，煤岩力学强度越靠近断层越低；且裂隙的力学性质向断层面方向由张性向张扭、压扭性再到张性转化；断层导致初始应力场的挠动，局部产生附加应力。在采动影响下断层“活化”，随着距断层面距离的减小，工作面前方煤（岩）体中支承压力均明显增大，支承压力峰值位置向前方煤岩体中转移，在回采工作面煤壁和其前方断层之间煤柱之上压力分布类似于小的残留煤柱的情况，煤柱愈窄，压力峰值愈高，煤的抗压强度是残留煤柱承压作用的极限。

Influence of normal faults on the physical and mechanical properties of coal and the distribution of underground pressure

Through the observation of micro fractures and pores, the mechanical experiment and numerical simulation,it is systematically revealed the influences law of normal faults on the physical and mechanical properties of coal and the distribution of underground pressure. The test results indicate that coal (rock) mass in fault zone and its influential range is broken. The closer to fault plane, the more fractures in coal (rock) mass and the less mechanical strength of coal (rock) mass are. The mechanical properties of fractures change from extension to tension shear, and from tension shear to compression shear, then in turn to extension towards fault plane. The fault induces changes of initial stress field and additional stress in some areas. The fault activation is induced during coal mining. The abutment stress ahead of working face obviously increases and the peak value position of abutment stress migrates to the inside of coal mass with reduction of distance away from the fault. The pressure distribution which acts on the pillar between the coal wall of working face and the frontal fault, is similar to the residence pillar that the peak value of pressure appear at the middle of pillar. And the thinner the pillar, the bigger the peak value is, the coal compressive strength is the limit of resident pillar abutment pressure.