Research On Optimization Of Static Roof Cutting And Stress Releasing Parameters At The Side Of Mining Roadway

Along with the deep popularity of the concept of non coal pillar mining,the technology of gob-side entry retaining has been developed and popularized rapidly in a short period of several decades because of its unique engineering characteristics and advantages.However,the deformation of the surrounding rock of the retaining entry under the strong support is still so seriously affected by the strong dynamical mining pressure.In order to solve the problem that stunts the promotion and development of the technology,many scholars at home and abroad have studied the spatial structure and mechanical characteristics of the gob-side entry retaining,and gradually summed up the control means of the surrounding rock along the gob with the core of the roof cutting and stress releasing technology.It has achieved many fruits in the field practice.Through the analysis of the current research status in the field at home and abroad,it can be seen that the main technical measures to deal with the cutting and releasing of the top of the gob-side entry retaining are blasting precracking,hydraulic fracturing and high-pressure gas precracking.However,because the detonationenergy releasing of explosive materials is too large and its controllability is hard,it is easy to induce major safety accidents in the mine,so the use of blasting presplitting and stress releasing method is limited in some high gassy mine.Although the hydraulic fracturing stress releasing method can avoid the problems of hidden danger in the method of blasting presplitting and stress relief,the equipment has higher equipment and be easy to cause difficult drainage in the working area,and it is difficult to achieve the fracturing pressure of the cracking requirements.Based on the defects of the existing technology and the characteristics of the urgent demand to solve the problem,according to the engineering application characteristics of the static crushing agent,the technology is considered to be introduced into the roof cutting and stress releasing process of the mining roadway,and the static statics at the side of the mining roadway are analyzed from three aspects of theoretical analysis,laboratory test and numerical simulation.Comprehensive research and analysis of the roof cutting and stress releasing technology has yielded some research results.Through the investigation on the auxiliary air entry(the gob-side entry retaining)in the 3108 working face of Xinyuan Mine,and referring to the relevant documents,the data of the geological features of the working face,the layouts of the roadway,the surrounding structure of the coal seam and the physical-mechanical parameters of the coal and rocks are collected,and the research and analysis of the static cutting and stress releasing of the gob is made.Through the analysis of the expansion mechanism of the static crushing agent,the influence characteristics of external factors on the expansion performance and the stage process of the reaction,the hydration reaction process and the size of the swelling stress at different water cement ratio,different inner aperture of steel tube and different water temperature are obtained by the laboratory improvement test.The breakage mechanism of rock is analyzed,and the relationship between the crack propagation mechanism and the formula of the expansion pressure in the borehole,the radius of the borehole and the distance between the drilling holes is obtained.The theoretical basis is provided for the subsequent determination of the rational hole spacing of the drill holes.The optimum hole spacing parameters are determined by numerical simulation,and the best construction scheme and parameters are determined through the comparison of the scheme.The parameter basis and the choice of the scheme are provided for the follow test,in addition,the deformation characteristics and variation of stresses of the surrounding rock before and after the static roof cutting and stress releasing are analyzed by numerical simulation.The static roof cutting and stress relief can improve the stress conditions and reduce the deformation of the surrounding rock,thus it can be explained that the static crushing and stress relief technique is effective for the control of the surrounding rock.Through the method of laboratory test,theoretical analysis and numerical simulation,this paper studies and optimizes the relevant parameters of the staticroof cutting and stress ureleasing technology at the side of the mining roadway.From a certain extent,the effect and characteristics of the static crushing and stress releasing are explained,which not only widens the application direction and field of static crushing technology.It can also play a certain role in promoting and innovating the technology of roof cutting and stress relief along the gob of entry remaining.This paper has a certain reference significance for the study of cutting andrelief under similar conditions.At the same time,it provides reference and reference for the method of reducing the error of the expansion performance test of static crushing agent.