Key technologies for prevention and control of water-sand inrush disaster in fully mechanized caving mining under rich water aquifer

Fully mechanized coal caving mining under the nearby rich water aquifer is very dangerous for the reason that the overburden of weakly consolidated coal seam has poor resistance to mining deformation and fracture caused by high intensity mining is easy to permeate the aquifer,which usually results in water-sand inrush. In order to realize the accurate prevention and control of water-sand disaster in fully mechanized caving mining under rich water aquifer,prevention and control technology of water-sand inrush disaster based on fine exploration of hydrogeological conditions,measurement and monitoring of overburden failure height,design and real-time adjustment of mining and caving height of coal seam is studied. A combination of fine exploration based on net parallel electrical method and encryption drilling is proposed to find out the hydrogeological conditions of mining working face. The overburden failure height characteristics of dynamic and static fully mechanized caving mining were obtained by using the empirical formula prediction,numerical simulation,measurement of borehole water injection method and the integrated monitoring of electricityseismic. By controlling the mining and caving height of coal seam,optimizing the position of two roadway in working face,inverse computation of mining and caving height by monitoring overburden fracture height using electricity-seismic,the mining and caving height of coal seam can be real-time adjusted. Taking the application working face as example,the method of parallel electricity,drilling testing,measurement of overburden failure height and precise control of mining and caving height of coal seam is adopted to dynamically control overburden failure range and realize fully mechanized caving safety mining under nearby rich water aquifer. The results show that hydrogeological information and the key parameters of overburden failure in fully mechanized mining can be effectively got by geophysical prospecting and drilling detection. Fully mechanized mining under nearby water rich aquifer can be safely conducted by combination the mining fracture with hydrogeologic conditions,controlling the mining and caving height,different measurements being taken to dewater or protect different aquifer.