Abstract
In longwall mining, the risk of water inrushes from the floors of deeply buried coal seams is closely related to the degree and depth of the destruction for the mining floor. To analyze the main factors affecting floor failure and the evolution of such failures, this study considered the LW2703 working face of the Chengjiao Coal Mine in China, which is characterized by a large buried depth, complex fault structure, and high pressure from a confined aquifer. The characteristics affecting floor crack development depth were analyzed by considering friction angle, cohesion force, floor pressure, stress increase coefficient, and peak position. A FLAC3D simulation was performed to compare the degrees of floor damage that occurred for caving and backfilling methods during the mining process. High-density electrical detection was performed on-site and used to (1) determine the maximum depth range of the floor damage, (2) reveal the laws governing the evolution of damage in a mining floor, and (3) provide a reasonable basis for evaluating and preventing floor water inrush accidents.
Highlights
As Chinese coal mines gradually become deeper, their hydrogeological conditions become increasingly complex.e combination of ground and water pressure has made water damage more prominent and increased the frequency of floor water inrush accidents
Floor water inrushing occurs when certain basic conditions are satisfied for a water source and channel
For the north China coalfield, the water source is generally the water-filled aquifer of the Carboniferous and Ordovician systems. is indicates that the safety of a mining face depends mainly on channel formation, which is controlled by many factors
Summary
As Chinese coal mines gradually become deeper, their hydrogeological conditions become increasingly complex. E LW2703 working face in the Chengjiao Coal Mine is very deep, with a complex fault structure and high water pressure. Because of these characteristics, the face has a high water inrush risk, which threatens safe mining and production. High-density electrical detection was performed in the eld and used to (1) determine the maximum depth of oor damage, (2) reveal the laws governing the evolution of damage in a mining oor, and (3) provide a reasonable basis for evaluating and preventing oor water inrush accidents. The natural ssures in the lower part of the aquifer develop upwards, which further reduces the thickness of the water-resisting layer and can cause water inrush accidents at the working face
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