Abstract
This paper focuses on the responses of overburden stress and pore water pressure in confined aquifer to mining under the Ordovician limestone aquifer and the reverse fault. Taking 32 coal seam mining in the first eastern mining area of Qianyingzi coalmine in China as engineering background, on the basis of the mining hydrogeological and engineering geological model of the study area, a numerical calculation model considering the fluid-solid interaction is established. Simulation results indicate that the variation characteristics of pore water pressure in confined aquifer and overburden stress are affected by both mining effect and geological tectonics and are closely related to the shear failure of the reverse fault plane caused by mining effect and the failure characteristics of the overburden strata in the stope. According to the variation of pore water pressure before and after the roof water inrush, the reduction range of pore water pressure can be used as one of the early warning indicators for water inrush accidents. These new understandings are of reference value to the mining water inrush under the combined action of reverse faults and confined aquifers and to the establishment of corresponding forecasting and early warning systems.
Highlights
It is a key theoretical problem of coal mine disaster control and prevention that the variation of overburden stress and pore water pressure in confined aquifer caused by coal mining
Different from the coal mining under loose aquifer, the roof water inrush mechanism and overburden failure characteristics of coal mining under limestone (Ordovician limestone and Cambrian limestone) aquifer are often coupled with faults, which make the geological conditions of the stope more complex
In this paper, taking 32 coal seam mining in the first eastern mining area of Qianyingzi coalmine in China as engineering background, the responses of overburden stress and water pressure in confined aquifer to mining under the Ordovician limestone aquifer and the reverse fault are studied with using FLAC3D software, which is aimed at revealing the roof water inrush mechanism of mining under the Ordovician limestone aquifer and the reverse fault and establishing the early warning and prediction index of roof water inrush caused by mining under the combined action of reverse faults and confined aquifers
Summary
It is a key theoretical problem of coal mine disaster control and prevention that the variation of overburden stress and pore water pressure in confined aquifer caused by coal mining. Different from the coal mining under loose aquifer, the roof water inrush mechanism and overburden failure characteristics of coal mining under limestone (Ordovician limestone and Cambrian limestone) aquifer are often coupled with faults, which make the geological conditions of the stope more complex. The current research pay less attention on the issue of mining under a double threat from both the fault and roof confined water, especially in the variation of overburden stress and pore water pressure under these special geological conditions. In this paper, taking 32 coal seam mining in the first eastern mining area of Qianyingzi coalmine in China as engineering background, the responses of overburden stress and water pressure in confined aquifer to mining under the Ordovician limestone aquifer and the reverse fault are studied with using FLAC3D software, which is aimed at revealing the roof water inrush mechanism of mining under the Ordovician limestone aquifer and the reverse fault and establishing the early warning and prediction index of roof water inrush caused by mining under the combined action of reverse faults and confined aquifers
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