Abstract:

In order to minimize the influence of coal mining on inclined shaft structures, the rational dimensions of protective coal pillar have to be calculated. The coal pillar dimensions are calculated by empirical formula method, 2D discrete element model is established, the distributions of internal force and displacement of segment of inclined shaft are analyzed, and rational dimensions of protective coal pillar are given by considering 5 different crosssections of groundinclined shafts. Some conclusions are drawn as follows: 1) The coal pillar dimensions calculated by discrete element model are smaller than that calculated by empirical formulas. 2) The inclined shaft structure uplifts a little and then sinks obviously with the vertical distance between coal mining working face and inclined shafts decrease. 3) The inclined shaft displaces away from coal mining working face as a result of the sagging pressure from the overlying broken rock layers when the vertical distance between coal mining working face and inclined shafts is comparative small. 4) The inclined shaft structure displaces towards coal mining working face when the vertical distance between the coal mining working face and inclined shafts is large enough. 5) The bearing capacity of inclined shaft structure might become insufficient due to stress concentration at the interfaces of rock and coal layers with distinctively different physicomechanical properties; thus the improvement and control methods are necessary.

Key words: coal seam, inclined shaft, segment, coal pillar dimensions, empirical formula method, discrete element simulation