Full-length hydraulic fracturing pressure relief mechanism and multi-parameter effect anlysis of long horizontal and deep hole in isolated working face

Abstract

To solve the strong dynamic pressure problem faced by the roadways under deep island working face conditions, the three types of overhanging roof in the lateral mining area of the working face, overhanging roof in the side of the mining area of the working face and overhanging roof of the upper high rock structure under complex stress condition in the back mining roadway are analyzed. The type of deep hole fracturing is analyzed, and a full-length hydraulic fracturing arrangement based on long horizontal holes is proposed. It has been applied in 3203 island working face of a mine. By fracturing long horizontal holes in different layers of target rock, the full-length pressure relief treatment of strong dynamic pressure roadway in isolated island working face is realized. The mine pressure is observed in stope and roadway and the evaluation indexes are selected. Through multi-parameter and phased analysis, it can be found that: this pressure relief method can build a weakening band in the roof, achieve the effect of improving the spatial structure of the end of the working face and the roof above the goaf, shorten the working face periodic weighting distance, reduce the peak value of the leading supporting stress of the working face, optimize the distribution state of the stress field in the leading area of the working face from the perspective of time and space, transfer the high stress of the coal pillar and the surrounding rock of the roadway, and reduce the influence of mining stress. The amount of roadway deformation during mining is significantly reduced, and the safe and efficient mining of isolated island working face is realized.

Keywords

• isolated working face
• overhanging roof
• overlength horizontal hole
• full-length hydraulic fracturing
• pressure relief effect