Study On The Mechanism And Control Technology Of Energy Storage Induced Scour In Hard Roof

In the process of working face advancing,because the hard roof is not easy to collapse,a large amount of energy accumulation in the hard roof is very easy to induce rock burst.The rock burst caused by improper control of the hard roof is a long-term threat to the safety of mine production.Taking the 6304 working face of Yunhe Coal Mine as the research background,this paper studies the mechanism and control technology of energy accumulation induced scour of hard roof by means of data collection,theoretical analysis,numerical simulation and field test.The main results are as follows:(1)Considering the actual situation of 6304 working face and combining with the knowledge of elastic mechanics,the analytic formula of energy before and after the fracture of hard roof plate is deduced by building the mechanical analysis model,and the energy solution before and after the fracture of hard roof plate is finally obtained.The results show that the energy difference before and after the fracture of hard roof is large,which means that a lot of energy is released in the mining space during the fracture of roof plate The attack risk is high.According to the actual situation of roof strata,the failure mode of roof is analyzed and judged.It is theoretically calculated that the ultimate span of 6304 working face roof when tensile failure occurs is greater than shear failure.The calculation results show that the hanging distance of hard roof is too large to fall in time.Further,it proves the necessity of hard roof control and the generality of energy accumulation of hard roof The influencing factors and key influencing factors are analyzed.(2)Based on FLAC3D numerical simulation software,the dynamic failure and stress state of hard roof in different advancing stages of working face are simulated and analyzed firstly,then the energy distribution characteristics of hard roof and the energy release law of roof fracture are analyzed;by changing key parameters,the influence of hard roof thickness,working face mining width and goaf on the energy accumulation of hard roof is simulated It is found that the narrow working face is more likely to cause the energy concentration of the hard roof.With the increase of the thickness of the roof,the energy concentration will be higher.Under the influence of the goaf,there will be asymmetric distribution on both sides of the working face,which makes the control of the hard roof more complex.(3)In view of the control problem of hard roof,a deep hole presplitting blasting technology is proposed.The blasting parameters and blasting scheme are determined by previous experience accumulation and mathematical equation calculation.The spacing between boreholes is determined as 10 m.the step spacing is reduced by artificial blasting to reduce the degree of energy accumulation in the hard roof.After the field test,through the energy data collection of the pre arranged microseismic monitoring system,the effectiveness of the technology is verified by comparing the energy events before and after the implementation of the deep hole presplitting blasting technology.The large energy events detected in the mining stage are greatly reduced,and the hard top plate is basically controlled successfully,ensuring the production safety of the working face.