Study On The Mechanism And Control Of Surrounding Rock Instability Under The Dynamic Load Of Overburden Fracture In Deep Mining

The dynamic stress field formed by the movement of mining overburden causes the stope and surrounding rock mass to be in a state of long-term and frequent disturbance,resulting in the dynamic disaster of adjacent goaf roadway.Based on stress wave theory,disturbance state concept theory,creep theory,indoor physical similarity simulation and rock basic mechanical properties test,FLAC^3D numerical simulation,orthogonal test principle and outdoor field test,taking the deep roadway of Hongyang No.3 Mine in Shennan mining area as the engineering background,this paper studies the disaster mechanism of roof fracture and the deformation and failure of the surrounding rock of the deep adjacent goaf roadway.The influence factors and deformation mechanism of large deformation of surrounding rock under dynamic disturbance are analyzed,the failure mechanism of rock is revealed,and the supporting scheme to control the deformation of surrounding rock is proposed.（1）The mechanical model of the roof fracture of the working face is established,the dynamic load characteristics and propagation mechanism of the surrounding rock of the roadway under the influence of mining are analyzed,the mode and distance of the roof fracture of the working face are obtained,the relationship between the dynamic load intensity of the adjacent empty roadway and the dynamic load of the roof fracture is revealed.Through the similar simulation experiment,the movement characteristics,structural characteristics and dynamic load response of the adjacent goaf are verified.（2）The fatigue test of sandstone under cyclic loading is carried out by MTS-815 rock mechanics test system and acoustic emission system.The influence of stress amplitude and loading frequency under cyclic loading conditions on its fatigue damage characteristics is discussed.The stress-strain curve characteristics,energy dissipation characteristics,acoustic emission characteristics and strain damage evolution process of sandstone under graded cyclic loading are analyzed.On the basis of creep theory and disturbance state theory,the theoretical model between peak strain and cycle number under cyclic load is established.Through the test data,the parameters of the strain damage model of sandstone based on the disturbance state concept theory are identified,and the rationality of the model is verified.（3）According to elastic theory and stress wave theory,the instability mechanism of high stress roadway surrounding rock under disturbance is analyzed.The ideal elastic-plastic model of roadway surrounding rock is established by FLAC^3D software.On the basis of orthogonal optimization combination,the sensitivity analysis of the factors（disturbance amplitude,frequency,side pressure coefficient and disturbance time）that affect the deformation of roadway surrounding rock under dynamic disturbance is carried out.The mathematical formulas of roof deformation,floor deformation,side deformation,roof plastic area,floor plastic area and side plastic area under the action of multiple factors are established by using multiple linear regression analysis.The regression effect is very significant.（4）Due to the influence of structural stress and mining conditions,there are strong characteristics of mine pressure in the working face of the second west mining area of Hongyang No.By using microseismic monitoring system,roof dynamic monitoring instrument and FLAC^3Dnumerical simulation software,the characteristics of microseismic activity and roadway deformation and failure in deep mining face are studied,and the mechanical response characteristics of surrounding rock and support body before and after dynamic load are simulated.The original supporting scheme is optimized by theoretical analysis and numerical simulation,and the supporting effect is improved,which has guidance and reference value for practical engineering.