Experimental Study On Catastrophe Mechanism And Safety Control Of Gob-Side Entry In Deep Fault Structure Area

The impact failure of roadway is one of the dynamic disasters in coal mine,which mainly occurs in high stress coal pillar or fault and other geological structure areas.With the increase of coal demand,shallow coal resources are increasingly exhausted.Thus,coal mining gradually enters into deep mining state.Influenced by "three highs and one disturbance" in deep surrounding rock,roadway roof fall,rock burst and other disasters are serious,which threaten the safety production of coal mines.Especially in the mining process of deep fault structure area the structure of surrounding rock near gob side entry is complex due to faults and coal pillars,and the roadway is prone to disaster.Therefore,the mechanism and control methods of gob side entry disaster in deep fault structure area need to be further studied.On this background,this paper mainly carried out the following research work,and relevant conclusions are achieved.(1)Numerical experimental study on catastrophe mechanism of gob side entry in deep fault structure areaTaking the case of 2305,working face rock burst in longgu coal mine as the research object.The numerical calculation model of gob side entry in deep fault structure area is established.The stress evolution and energy migration of surrounding rock are studied under different fault parameters and coal seam parameters.The catastrophe mechanism of gob side entry in deep fault structure area is revealed.?The larger the fault dip angle is,the more difficult it is for the surrounding rock near the fault to form a balanced structure.The mine pressure is obvious,and the surrounding rock pressure near the fault is transferred to the roadway,which leads to the continuous increase of the surrounding rock stress of the roadway along the goaf.However,when the fault dip angle exceeds a certain angle,the interaction between the upper and lower walls of the fault decreases,and the stress between the roadway along the goaf and the surrounding rock near the fault begins to decrease.? As the strike of fault larger,the triangle coal pillar is graduating smaller.Therefore,the energy is continuously accumulated in the triangle coal pillar area in front of the working face.The high energy is mainly concentrated in the gob side entry and the surrounding rock near the fault.Affected by the mining disturbance,the accumulated energy of the surrounding rock exceeds the limit value,which is easy to cause roadway disaster.? The larger the fault fall,the higher the stress concentration and energy accumulation of surrounding rock near the fault.The peak stress and energy of surrounding rock near the hanging wall of the fault are 6.3%and 2.4%higher than those near the footwall,respectively.The greater the height difference between the upper and lower wall coal seams,the higher the surrounding rock stress near the hanging wall fault is affected by the interaction between the upper and lower wall,which is easy to cause fault instability(2)Experimental study on model test of gob side entry in deep fault structure areaThe stress,displacement and overburden movement characteristics of surrounding rock in the goaf in the deep fault structure area during the mining process of working face are studied.The rationality of numerical test is verified,and the law of overburden movement and surrounding rock stress change in the working face mining process is obtained.? The results show that the displacement of the surrounding rock of the roadway roof monitored by the model test is similar to that of the numerical test at the corresponding monitoring point,and the average difference rate of the displacement of the surrounding rock of the roadway is 13.4%,which verifies the effectiveness of the numerical calculation results.? In the early stage of working face,the gob side entry is affected by the goaf and coal pillar,and the stress concentration area appears in the deep surrounding rock of the roof.The stress of the surrounding rock in the deep mining face decreases with the increase of the surrounding rock stress.? The shallow measuring point of the roof of the roadway is located in the coal seam,which is greatly affected by the advance mining,with the maximum displacement of 400mm;the deep measuring point is located in the hard sandstone layer,and the displacement is only 56mm.(3)Research on safety control method of gob side entry catastrophe in deep fault structure areaIn order to reduce the energy accumulation degree of deep hard surrounding rock,combined with the results of numerical and model test,the method of roof cutting and self forming roadway in deep fault structure area is established,and the numerical comparison test between roof cutting and self forming roadway in deep fault structure area and gob side entry is further carried out.The prevention and control effect of roof cutting and self forming roadway in deep fault structure area on roadway disaster in deep complex fault area is clarified It can provide some guidance for the safety control of gob side entry catastrophe in deep fault structure area.? The peak value of lateral support pressure and energy peak of surrounding rock of the roadway automatically formed by roof cutting are 21.6%and 20.03%lower than that of the gob-side entry.The peak position of the lateral support pressure and the peak position of the surrounding rock energy of the roadway automatically formed by roof cutting are about 4-6m higher than that of the surrounding rock of the gob-side entry.The method of the roadway automatically formed by roof cutting in deep fault structure area can effectively cut off the stress transfer between the goaf roof and roadway roof.It was reduced the stress concentration and energy accumulation of surrounding rock near the roadway,make the lateral supporting pressure and energy peak position of the surrounding rock away from the roadway,and reduce the possibility of the roadway catastrophe.? When mining the method of the roadway automatically formed by roof cutting in deep fault structure area,the stress and energy peak of surrounding rock in front of the working face are 17.4%and 21.2%lower than that of the gob-side entry.The peak stress of surrounding rock in front of the working face can be effectively reduced in the mining process.It has a certain safety control of roadway catastrophe in deep fault structure area.