LAUSR

The fracture and behavior of multi-hard and thick roofs differ from those of other types of overlying strata. Therefore, abnormal rock pressure problems, such as gateway instability, rock burst, and hydraulic cylinder damage, will be encountered as a result of the instantaneous fracture of roofs. The key to controlling the behavior of the strata is to obtain the movement and fracture patterns of multi-hard and thick roofs. The periodical characteristics and occurrence zones of microseismic (MS) events of M mine with multi-hard and thick roofs were analyzed in the case study. Then the mining-induced fracturing and movement of the roofs were investigated. Anti-burst measures, including the “ultra-deep hole pre-split blasting measure,” the “stronger large-diameter boreholes pressure relief measure,” and the “reducing advancing speed measure,” were implemented according to the conclusions from MS monitoring. Finally, the aim of “there were earthquakes, but there were no accidents” was achieved through these measures.