Failure mechanism of the high pressure water in the Weibei on the top of the seams floor aquifers

摘要

Ordovician limestone aquifer of Weibei Chenghe mining area with abundant water, characteristics of water pressure, and No. 5 coal seam floor aquifer from Ordovician limestone top interface is relatively close distance, so it is a threat for No. 5 coal production safety. Before the coal seam mining, the floor water layer of No. 5 coal seam is in a stable equilibrium state. After the coal seam is mined, coal seam floor aquifer will cause the strata above the coal seam floor rock from the top to the bottom of the formation of coal seam floor damage, effective protection of aquifuge and water flowing zone because of the impact force of rock pressure and confined waterpressure. The floor mining failure will occur at the top of the water resisting layer and form the mining failure zone of the floor; at the same time, the change of the mechanical structure of the floor will cause the pressure of the confined water at the bottom of the aquiclude to lead up and down along the primary fracture and form a confined water rising belt. With the continuous exploitation of the coal seam, the mining failure zone of the floor may be connected with the ascending zone of the confined water, thus causing the floor water bursting along the through fracture formed by the mining. The current literature does not give a definite answer about the pressure of water on the floor mining failure with the formation of the influence of mining damage depth in the end how much, but from a simple numerical simulation and physical simulation study cannot fully reveal the phenomenon. Therefore, it is necessary to carry out research on failure mechanism of Ordovician limestone confined water on rock layer at the top of water resisting layer of coal seam floor, and from the point of view of mechanical action mechanism, the influence of confined water pressure on the mining failure depth of bottom plate is analyzed, which makes up the blank in this field. The research results of this paper play a key role in the study of the coupling mechanism between the confined water pressure and the mine pressure for further study and can provide reference for similar coal mines in North China type coalfield.