Decompression Deformation and Stress Distribution of Underlying Coal Seam in Upper Protective Coal Seam Mining

Abstract

To grasp the pressure and failure deformation and stress distribution of the underlying coal seam during the mining process of the protective coal seam, and improve the effect of the upper protective coal seam mining to prevent the coal seam and gas outburst of the underlying coal seam, this paper takes the Ⅵ16-17 coal seam of Pingdingshan No.4 mine in Henan Province as the object. Based on the Poyting-Thomson model, the creep dynamics model of coal and rock mass is constructed. The Comsol Mutiphysics 5.2 is used to simulate the deformation and deformation law of the underlying coal seam and the engineering verification. The results show that with the advancement of the upper protective layer working face (from 10 m to 60 m), the left and right sides of the underlying coal seam form a relief angle of 98.5° and 114° respectively, and the lateral plastic deformation increases to a maximum of about 216 m; the coal seam is characterized by plastic deformation to deformation recovery, which indicates that the exploitation of the upper protective layer contributes to the formation of gas depressurization channels in the underlying coal seam, which is beneficial to the extraction of gas in the underlying coal seam.

Keywords

• protective layer
• pressure relief angle
• numerical simulation
• stress distribution
• plastic deformation