Mechanism And Application Of Pressure Relief For Roof Cutting With Dense Drilling

The main coal seam in Datong mining area is mostly hard roof.After mining face,due to overburden failure to collapse in time to fill the gob,the peak load and lateral support pressure of the face and the influence range have increased significantly.Based on the engineering background of 8311 working face and 8312 working face in Sanpan District of Tashan Coal Mine,this paper studies the mechanism and technology of narrow coal pillar stability control in double-drilling tunnel under hard roof conditions.This paper proposes a new type of "dense drilling weakened roof" new cutting roof pressure relief technology,using a combination of numerical calculation and field practice to study the mechanism and key technical parameters of dense drilling weakened roof.A numerical calculation model for narrow coal pillars in the double-lane tunneling section was established,and Taylor polygons were used to divide the key research areas of 6m section narrow coal pillars and roofs to improve numerical calculation accuracy and reliability;different angles and depths of intensive drilling were studied The characteristics of crack development and distribution,failure form,plastic zone range and vertical stress distribution in the coal pillar under the coal column are summarized.The range of the plastic zone with bearing capacity in the center of the coal pillar under different drilling angles and depths is summarized;The deformation characteristics of the roof under the angle and depth and the development and failure forms of the cracks inside the roof have obtained the damage degree of the rock mass above the roadway and coal pillars under different drilling angles and depths as well as the size and scope of the complete area.By comprehensively comparing and analyzing the destruction degree of section coal pillars and roof under different drilling angles and depths,the technical parameters of dense drilling to weaken roof are determined.In the 2311 roadway,an industrial test of intensive drilling to weaken roof cutting and pressure relief was carried out,and a set of "dense drilling + roof anchor cable reinforcement support + section coal pillar to anchor cable reinforcement support" was proposed.Technical scheme for narrow coal pillar stability control in roadway driving section.Industrial tests have shown that: the deformation of surrounding rock in the test section of dense drilling is reduced compared with the section without drilling;the stress increase of the roof cable is 56% lower than that of the section without drilling;the surrounding rock on the side of coal pillar and coal body The peak stress is generally smaller than the test section without drilling.The paper has 59 pictures,4 tables,and 70 references.