Study On Failure Mechanism And Control Technology Of Composite Roof With Medium Thick And Weak Strata In Roadway

In the process of coal mine safety production,the control of roof safety is one of the important problems in the prevention and control of coal mine safety accidents in our country.However,there are few studies on the support of composite roof with medium-thick and weak strata in roadways.In the case of unreasonable support methods,there will be considerable potential safety hazards.Therefore,it is necessary to analyze the deformation mechanism and failure mechanism of composite roof with weak strata in roadway,and put forward corresponding strengthening support technology,which can provide reasonable and effective reference basis for surrounding rock control of similar composite roof roadway.Based on the background of roof separation failure control in three downhill roadways of Hongyan Coal Mine,this paper explains the serious roof subsidence and failure of support body in three mining areas of Hongyan Coal Mine by means of theoretical analysis and numerical simulation,roof structure and failure mechanism of roadways under existing support modes,and obtains the roof separation failure mechanism by combining bolting and grouting reinforcement control technology.The corresponding roadway reinforcement scheme is verified by field engineering contrast test in the later stage.The main conclusions are as follows:(1)According to the characteristics of composite structure of weak strata in the roof of downhill roadway in Hongyan Coal Mine,the failure mechanism of roof separation is analyzed from the mechanical point of view.It is concluded that the separation failure of weak stratum composite roof is easy to occur at the lithologic interface between weak strata and hard strata,which leads to serious roof subsidence and roof fall accident.Through the application of numerical simulation software,the stress distribution law of surrounding rock and the plastic failure range of roadway under the influence of different layouts and adjacent working faces are analyzed and studied.(2)According to the characteristics of separation failure of composite roof with medium thick and weak strata in roadway,through the mechanism of grouting reinforcement of roadway surrounding rock and the coupling effect of decompression and span reduction of anchor cable bearing arch,the bolting and grouting reinforcement scheme for downhill mining area in Hongyan Coal Mine is determined,and the relevant parameters of bolting and grouting reinforcement scheme are determined according to the actual situation in Hongyan Coal Mine.(3)According to the actual situation and monitoring results,the effect of bolt-grouting reinforcement support scheme is determined by comparative analysis.The results show that the bolt-grouting reinforcement support scheme can effectively fill the surrounding rock cracks and give full play to the bearing capacity of bolt and cable in time.It can improve the integrity and strength of the surrounding rock of roadway and control the stability of the surrounding rock of composite roof roadway with soft rock strata.