基于微震监测关键层破断诱发冲击地压的物理相似材料模拟实验研究

Similar material simulation experimental study on rockbursts induced by key stratum breaking based on microseismic monitoring

为研究冲击倾向性顶板破断及其能量释放规律,采用物理模拟材料模拟实验,结合微震监测仪器、压力传感器,研究实体煤和采空区下回采工作面微震事件的分布特征及其与矿压分布规律之间的关系,分析矿压对煤岩体能量积聚与释放的影响,揭示关键层破断诱冲机制。研究表明:实体煤下微震事件主要发生在工作面前方顶板岩层中,微震事件能量释放值高于采空区下;采空区下微震事件主要发生在工作面后方顶板岩层中,微震事件发生的频次高于实体煤下回采。依据相似定理推导了能量相似比公式,定义物理相似材料模型中覆岩垮落发生大事件的能量值为333.33 J,发现大事件多发生在应力增高区"倒梯形"结构附近。随着工作面距离开切巷距离的缩短,微震事件能量积聚与释放周期随之减小。关键层破断诱发冲击地压时,主关键层积聚弹性能为冲击地压显现提供能量,冲击地压显现的位置一般处在受采动影响的应力增高区。为此,提出控制源头、降低应力集中、降低应力传导效率的控制策略,工程实践效果监测表明工作面顶板得到了有效控制,保障了安全生产。

In order to study the breakage and energy release regularity of impact tendency roofs,physical similar material simulation experiment was carried out,and the distribution characteristics of microseismic events under the solid coal and the goaf and the relationship between microseismic events and the rock pressure were studied combined with microseismic monitoring instruments and pressure sensors.The influence of the rock pressure on energy accumulation and release of coal and rock mass was analyzed,and the mechanism of rockbursts induced by breakage of the key strata was revealed.The results show that the microseismic events under the solid coal mainly occur in the roof strata in front of the working face and that the energy release value of microseismic events under the solid coal is higher than that under the goaf.The microseismic events under the goaf mainly occur in the roof strata behind the working face,and the frequency of the microseismic events is higher than that under the solid coal.Based on the similarity theorem,the formula of the energy similarity ratio was deduced,and the energy value of large events in the physical similar material model was defined as 333.33 J.It was found that large events mostly occur near the inverted trapezoidal structure in the stress increasing area.With shortening the distance between the working face and the open-cut roadway,the period of energy accumulation and release of microseismic events decreases.When rockburst is induced by breakage of the key stratum,the elastic energy accumulated in the main key stratum provides energy for rockburst.The location of rockburst is generally in the stress increasing area affected by mining.The control strategies of controlling source,reducing stress concentration and conduction efficiency were put forward.The engineering monitoring results show that the roof of the working face is effectively controlled and safety production is guaranteed.