摘要
When mining extra-thick coal seams,the main cause of strong ground pressure are the high-level thick and hard strata,but as yet there is no active and effective control technology.This paper proposes the method of subjecting hard roofs to ground fracturing,and physical simulation is used to study the control effect of ground fracturing on the strata structure and energy release.The results show that ground fracturing changes the structural characteristics of the strata and reduces the energy release intensity and the spatial extent of overburden movement,thereby exerting significant control on the ground pressure.The Datong mining area in China is selected as the engineering background.An engineering test was conducted on site by ground horizontal well fracturing,and a 20-m-thick hard rock layer located 110 m vertically above the coal seam was targeted as the fracturing layer.On-site microseismic monitoring shows that the crack propagation length is up to 216 m and the height is up to 50 m.On-site mine pressure monitoring shows that(1)the roadway deformation is reduced to 100 mm,(2)the periodic weighting characteristics of the hydraulic supports are not obvious,and(3)the ground pressure in the working face is controlled significantly,thereby showing that the ground fracturing is successful.Ground fracturing changed the breaking characteristics of the high-level hard strata,thereby helping to ameliorate the stress concentration in the stope and providing an effective control approach for hard rock.
基金
This work was supported by the State Key Research Development Program of China(Grant No.2018YFC0604500,2018YFC0604506)
by the China Postdoctoral Science Foundation(Grant No.2019M651080)
as an applied basic research Project of Shanxi Province(Grant No.201901D211030)
by the Scientific,Technological Innovation Programs of Higher Education Institutions in Shanxi(STIP)(Grant No.2019L0208)
as a Major Program in Shanxi Province(Grant No.20191101015)
as a Distinguished Youth Funds of National Natural Science Foundation of China(No.51925402).
