顶板水力压裂防治冲击地压效果评价研究

Effect Evaluation of Roof Hydraulic Fracturing on Rock Burst Prevention

水力压裂在顶板型冲击地压防治中应用广泛。为了研究顶板水力压裂在红庆河煤矿402工作面应用效果,基于微震监测数据使用峰度和偏度指标对工作面在实体煤、单侧采空、水力压裂3种开采时期煤岩体破裂的分布形态进行了定量化研究;同时使用微震能量及b值评价了3个开采时期冲击危险性的变化。研究结果表明:水力压裂开采阶段和单侧采空开采阶段的偏度分别达到-0.677和-0.317,水力压裂开采阶段的负偏态性高于单侧采空时期,煤岩体破裂区域前移;水力压裂开采阶段的峰度为0.302,低于单侧采空时期的0.846,煤岩体破裂集中程度显著降低,水力压裂改变了煤岩体破裂的分布形态。与单侧采空开采阶段相比在更高的开采强度下,水力压裂开采时期的微震事件总频次显著增加、微震总能量和每米释放能量明显降低,煤岩体内积聚的总能量呈现降低态势,煤岩体内的弹性能以小能量的形式进行释放;水力压裂开采阶段的b值明显高于单侧采空开采阶段,水力压裂的施工降低该开采区域的冲击危险性。

Hydraulic fracturing is widely used in roof rock burst prevention.In order to study the application effect of roof hydraulic fracturing in the 402 working face of Hongqinghe coal mine,based on the microseismic monitoring data,the kurtosis and skewness indexes were used to quantitatively study the distribution patterns of coal and rock fracture in the working face in three mining periods:solid coal,single-side gob and hydraulic fracturing.At the same time,the variation of impact risk in three mining periods is evaluated by using microseismic energy and b value.The results show that the skewness of hydraulic fracturing and single-side caving reaches-0.677 and-0.317,respectively.The negative skewness of hydraulic fracturing is higher than that of single-side caving,and the fracture area of coal and rock moves forward.The kurtosis of hydraulic fracturing is 0.302,which is lower than 0.846 in single-side caving period.The concentration of coal and rock fracture is significantly reduced,and hydraulic fracturing changes the distribution pattern of coal and rock fracture.Compared with the singleside mined-out mining stage,the total frequency of microseismic events in the hydraulic fracturing mining stage increases significantly,the total microseismic energy and the energy released per meter decrease significantly,and the total energy accumulated in the coal and rock mass decreases.The elastic energy in the coal and rock mass releases in the form of small energy.The b value of hydraulic fracturing is significantly higher than that of single side mined-out mining,and the hydraulic fracturing reduces the impact risk of the mining area.