Dense boreholes for weakening bottom layer by cutting roof and pressure relief of gob-side entry retaining

Abstract

In order to ensure the safe and smooth process of gob-side entry retaining of high stress thick coal seam bottom layer in Guhanshan Coal Mine, combined with the broken condition and gas condition of the regenerated roof, the necessity of adopting dense borehole to cut roof and relieve pressure of the gob-side entry retaining roadway at the bottom layer of Guhanshan Mine is verified by theoretical analysis and numerical simulation test. The inclined angle, depth and spacing of dense drilling holes were analyzed and optimized by using the slip and instability conditions of masonry beams and numerical simulation tests. The borehole parameters are applied to the field engineering practice, and the shrinkage of both sides of the roadway is 656 mm and the shrinkage of top and bottom is 545 mm, which can meet the requirements of safety and production.

Keywords

• layered mining
• bottom layer
• gob-side entry retaining
• dense boreholes
• cutting roof pressure relief