Study on improving mechanical behavior of sandstone hole wall in soft coal seam

Abstract

In order to study the mechanical behavior of sandstone on the wall of gas drainage borehole in deep coal seam under high temperature conditions and improve the efficiency of gas drainage, this article takes the sandstone in the rock hole section of the cross-seam gas drainage drilling hole in 1366 working face of Hengda Coal Mine as the research object, carring out triaxial compression test of sandstone under different temperature treatments, rheology-permeability test under different loads and drainage test of boreholes with expansive cement slurry. The test results show that the high temperature leads to the development of cracks in the specimen, the reduction of ultimate resistance strength, the expansion of structure, the increase of crack area and permeability, and the increase of residual gas content in rock hole section. The expansion cement slurry fills the cracks of sandstone, strengthens the anti-collapse protective layer, reduces the gas residual area, improves the gas drainage volume fraction of coal seam.

Keywords

• high temperature state
• volume damage threshold
• ultimate strength
• rheology permeability
• gas residual area