Analysis And Research Of Water Disaster Prevention For Extremely Thick Coal Seam In Tang Jiahui

The water disaster has always been one of the important reasons that hinder the safety production of the coal mine. The disasters resulting from the coal mining above the pressure-bearing water layer takes up more than 50% of the entire accidents caused by water. The primary coal seam in Tang Jiahui is coal seam 6 and the operation platform of 61101 is considered as the primary platform of the mine. The mining on the platform faces a great many of potential safety risks jointly affected by sandstone water from roof, Ordovician limestone water at the bottom, faultage fissure water and the ponding in the gob of the abandoned roadway. The average thickness of coal seam 6 is about 17 m. It is necessary to study and analyze the preventions about the water damage to the extremely thick coal in Tang jiahui mine because there is no mature experience to learn from with respect to the fact that the explorations of the over-thick coal will break the evolutionary characteristics.Under the background of the 61101 primary mining platform in Tang Jiahui coal mine featured with extremely thick coal seams, the thesis focuses on the research of the water disaster preventions and try to find out the changing features of the floor destructiveness for the over-thick coal seam mining and the solutions to handle water disasters. The study contents and the results achieved are as follows:1. Based on the hydrogeological conditions of 61101 mining platform, the author employs research methods of geophysical prospecting and misering to identify a series of problems such as the water-rich character for the aquifer of ordovician limestone, the development status of the mining platform structures, the water proof features of the floor rock stratum as well as its thickness and fracture change situations. After analyzing the research results, we discovered the isopach from coal seam 6 to the aquifer of Ordovician limestone, the thickness contours for the floor sandstone of coal seam 6, the thickness contours for the water-resisting layer of the floor and the distribution range for the abnormal area by the floor geophysical prospecting.2. Establish the construction geology models on the basis of the mechanical testing results for the 611101 platform floor rock. Under the conditions of 10.1 MPa of mine ground pressure and 1.2MPa of confined water pressure, the author utilizes the FLAC3 D numerical simulation software to perform stimulations on the pore water pressure, vertical stress as well as the distribution situations for the plastic failure zones of the floor rock stratum for coal seam 6 at different fault throws(5m, 10 m, 15 m and 20m) and propulsion distances(40m, 80 m, 120 m, 160 m and 200m), the results showed that:(1) When promoting the same distance, with the increase of fault throw, the maximum pore water pressure in the rock face floor increases; when the fault throw the same, with the continuous progress and close working face fault, the floor around maximum rock pore water pressure has also increased.(2) Face to the floor along the wall rock compressive stress, abutment pressure in the vicinity of face and the mined-out area formed part of a stress concentration. along the dip direction, basically at the rock face floor area of reduced pressure, and the floor around by the rock composition containing fine-grained sandstone and sandy mudstone, large compressive strength, rock working face of the base plate can remain stable without breaking.(3) Face in the roof and floor main tensile plastic zone in front of and behind the stope goaf shear plastic zone; the calculation takes into account the pore water pressure and Ordovician limestone, floor surrounding rock are rapidly produced plastic zone and its range is increased; as long as the surrounding rock face floor remained intact and Ordovician limestone water pressure does not exceed the strength of the upper portion of rock that can resist, it basically does not happen water inrush.3. Through the analysis on the factors that affect the water disasters for the safety operations of 61101 primary platform, the thesis has made an initial evaluation about the water inrush risk for the aquifer in floor Ordovician limestone existing in the mining with pressure for coal seam 6. During the process, several methodologies have been adopted including water bursting coefficient method, thickness ratio coefficient method for safety water-resisting layer and equations for safety water pressure. The calculation result is as follows:(1) The water bursting coefficient Ts is a critical value less than 0.06, between 0.025-0.033, which means low potentials for the happening of water bursting risk during the exploration for working platform.(2) The thickness ratio coefficients Tas for the safety water-resisting layer are all below 1, between 0.5035 and 0.7206. Therefore, it is not likely to have water bursting risks during the platform mining.(3) The maximum value of Ordovician limestone water pressure is 1.2MPa, which is far less than the safety water pressure value of 60.25 MPa set for the water-resisting layer. So the risk for the water bursting is small.4. The thesis estimates the quantity of inrush water for the platform and the mining. Considering the water disaster prevention experiences in the nearby mines, it also proposes an effective measures and solutions to prevent the water disasters.The achievements of this thesis has been put into the working practice of the water disaster preventions for the exploration of 61101 platform in the Tang jiahui mine, which enable the safety operations and has shown good results. All these achievements has provided precious experience to the task of water disaster preventions for the floor Ordovician limestone water in the over-thick coal seam and has brought fairly good economic and social profits, which can be popularized to the other mines across the country.