Journal of Engineering Research

Based on the risks of strong mining pressure and coal wall fragmentation caused by the overlying inclined coal pillar during the strong mining process of the underlying coal seam, FLAC3D software was used for engineering modeling to analyze the stress distribution characteristics of the bottom plate after the excavation of the overlying coal seam, and the evolution law of stress during the process of the working face passing through the inclined coal pillar was obtained. The results showed that: (1) After the excavation of coal seam 22, stress concentration occurred directly below the coal pillar, with a maximum stress value of about 18MPa. The strong influence range of the overlying coal pillar was about 60m on both sides of the coal pillar. (2) During the process of passing through the coal pillar, the pressure influence range of the advanced support of the 42202 working face gradually connects with the stress concentration zone below the coal pillar, forming a strip-shaped stress concentration zone; And as the working face advances, it gradually rotates until the working face passes over the coal pillar, and the two stress concentration zones gradually separate. (3) When the working face is located below the coal pillar, the peak forward support pressure of the working face is about 35MPa; Before entering the coal pillar at the working face, the pressure was about 33MPa; The minimum pressure after the coal pillar exits the working face is about 24MPa. Before entering the coal pillar at the working face, the maximum impact range of advanced support pressure is about 150m~200m; When the working face is directly below the coal pillar, it is about 80m-100m; The influence range of the advance support pressure after passing through the coal pillar on the working face is the smallest, about 45m~70m.

Underground coal mining; Key stratum; Strong mining; Dip coal pillar; Strata control