推进方式对断层围岩应力演化规律的影响

The influence of different mining modes on the evolution law of stress in fault surrounding rock

煤炭开采中的冲击地压与断层构造密切相关,而工作面分别沿断层上盘和下盘推进时具有不同的冲击危险。为研究工作面推进方式与断层活动的相关性,以某过正断层工作面为例,通过数值计算分析不同推进方式下断层两盘接触应力状态的演化过程,基于对推进过程关键层破断规律的分析,研究断层应力演化差异性产生的原因,并通过工作面实际回采过程的微震监测数据,验证了采动影响下断层活化规律。研究发现:上盘开采时的断层应力变化幅度大于下盘开采时的应力变化幅度,上盘开采时断层围岩系统应力传递能力优于下盘开采;推进方式会影响上覆岩层破断后的覆岩结构和应力传递,上盘开采时关键层破断后更易形成砌体梁结构,且结构体系的稳定性高于下盘开采,下盘开采时工作面冲击危险性更高,须根据断层性质做好工作面布置和开采优化,进而降低冲击地压危险。

Rock bursts in coal mining are closely related to the fault structure, and different risks of burst exist when the working face carries forward along the hanging wall and the foot wall of the fault respectively. In order to study the correlation between the advancing mode of working face and the ac- tivities of faults, with a working face over normal fault as an example, the evolution process of the stress state of the two sets of faults in different propulsion modes was analyzed through numerical calculation; based on the analysis of the breaking regularity of key stratum in the process of advancing, the reason for the difference of fault stress evolution is studied; the regularity of fault activation under the influence of mining is verified through the micro-seismic monitoring data in the mining process of the actual working face. It has been found that the fault stress change in the hanging wall mining is greater than that in the footwall mining, and the stress transmission capacity of the fault in the hanging wall miningis better than that in the footwall mining; the overlying rock structure and the stress transfer after strata breaking can be influenced by the advancing mode： during hanging wall mining, it is more likely for the key strata to become a voussoir beam structure, and its stability is higher than that in the footwall; dur- ing footwall mining, there is a higher risk of burst in the working face, so it is necessary to optimize the working face layout and mining technology according to the fault characteristics to reduce the risk of coal bumps.