Microseismic Real-time Acquisition And Dynamic Forecast And Application Research Of Floor Mining-induced Failure Depth

With the increase of mining depth in our country, the disaster of water inrush and slab rupture in coalface after mining is increasing year by year. Because of the floor damage by mining, the floor arise of deformation, and the frame appear to subsidence by the sharply reduction of bearing strength which increase the difficulty of moving frame. In addition, under the conditions of under pressure mining, the floor mining-induced damage reduced the thickness of water-resisting layer of coal floor, resulted in the decrease of bottom water resistance ability, and increased the risk of inrush. As a result, the dynamic real-time access of the coal mining-induced failure depth of floor and the stress distribution play an important role in the study of coal floor block water ability. This thesis take the floor water inrush risk of9th coal in First Underground Mine as a research object, and a series of technological means, such as theoretical analysis, numerical simulation, microseismic monitoring, are used to study the coal mining-induced floor deformation rules and damage depth. Finally, some innovative results are obtained as follows:(1) The support stress variation law and the stress distribution and propagation law in the strike of floor rock mass was got through the theoretical analysis of coal floor mining-induced stress state; The stress field and fracture field evolution law was obtained by discrete element numerical simulation software.(2) Through the microseismic real-time monitoring in9th19106coalface of Shanxi First Underground Mine, the microseismic wave propagation law was obtained. The shortest distance clustering method was used to cluster. The distance between microseismic events which expressed by Euclidean distance was used to estimate evaluate its closeness degree and classify reasonably. Finally, a general pattern was built to gain the mining-induced failure depth of floor.(3) Based on the unified strength theory, a general formula of the mining-induced failure depth of floor was inferred. The datasets of the mining-induced failure depth of floor from9th19106coalface in Pingshuo First Underground Mine were used to invert the two parameters of b, and build the formula of the mining-induced failure depth of floor which fit the9th coal in First Underground Mine.(4) Based on the unascertained mathematics theory, the dynamic forecast research of the mining-induced failure depth of floor was carried out. According to the results of microseismic monitoring, four main influencing factors, such as mining depth, coal seam dip angle, mining thick and structure impact, were regarded as judgment indexes and used to establish the dynamic forecast model of floor mining-induced failure depth by unascertained clustering method. The verification results show that the dynamic forecast model of mining-induced failure depth of floor is reliable and practical, and it could be popularized and applied to the similar mines.(5) The dynamic water inrush coefficient concept was raised to calculate the possibility of floor water inrush in19106working face. Based on the catastrophe theory, the microseismic monitoring results were used to gain the thickness of aquiclude in floor and dynamic water inrush coefficient. Finally, the method was used to evaluate the possibility of floor water inrush in19106working face which appeared little possibility.