Study On Mining Overburden Rock And Surface Movement Law Of Steeply Inclined Thick And Large Orebody

At present,with the continuous development of China’s mining industry and the continuous expansion of mining scale,various geological environment problems caused by underground mining are common.A large number of surface subsidence and deformation disasters caused by goaf collapse occur every year.The overburden rock and surface movement caused by the mining process of steeply inclined orebody is extremely complex.How to control the surface collapse of steeply inclined thick orebody is a recognized technical problem in the industry.Taking the underground mining of steeply inclined thick and large orebody as the research background,this paper uses a series of means such as theoretical analysis,numerical simulation analysis and similarity simulation analysis to carry out in-depth research on the overburden rock and surface migration law of steeply inclined thick and large orebody mining.The specific research results are as follows:(1)The main influencing factors and characteristic parameters of rock movement of steeply inclined orebody are analyzed,which provides a theoretical basis and calculation basis for the study of rock movement in mining steeply inclined thick and large orebody,summarizes the basic forms of overburden rock movement and failure,establishes a typical numerical simulation model,and analyzes the basic mechanism and typical characteristics of rock movement of steeply inclined orebody from displacement,stress and plastic zone,It is pointed out that the essential reason for the difference of strata movement and deformation law between steeply inclined orebody and horizontal orebody lies in the difference of stress components between them.(2)According to the basic influencing factors,characteristics and rock movement mechanism of steeply inclined orebody mining,taking the four main influencing factors of rock mass quality grade,mining depth,thickness and dip angle as the starting point,and using FLAC3 D numerical simulation software,detailed numerical simulation analysis is carried out from four angles: surface movement,overburden rock migration,stress analysis and plastic zone.It is concluded that with the improvement of rock mass quality grade,The surface settlement center gradually moves towards the hanging wall,the surrounding rock movement,surface settlement and deformation value are significantly reduced,and the reduction rate is reduced,and the maximum stress concentration factor in the hanging wall stress concentration area of goaf is significantly increased;With the increase of mining depth,the surface settlement and deformation value gradually increase and the increase rate is faster and faster.The maximum subsidence value point moves slightly downhill with the increase of mining depth.The displacement of hanging wall surrounding rock in goaf increases rapidly,the displacement of hanging wall surrounding rock in goaf increases slowly,and the maximum stress concentration factor in hanging wall stress concentration area decreases gradually;With the increase of dip angle,the surface settlement and deformation value gradually decrease,and the decreasing rate is slower and slower.The surface settlement center gradually moves to the footwall,the maximum horizontal displacement of surrounding rock gradually exceeds the maximum vertical displacement of surrounding rock,and the maximum stress concentration factor in the hanging wall stress concentration area of goaf gradually decreases;With the increase of thickness,the surface settlement and deformation value gradually increase and the increasing rate is faster and faster,the displacement of surrounding rock in the upper and lower walls also increases and the increasing rate is faster and faster,and the maximum stress concentration factor in the stress concentration area of the upper wall of the goaf gradually decreases.(3)In view of the defects in the existing delineation method of moving zone,the numerical simulation study is carried out on the mining of steeply inclined thick orebody with different buried depths of fixed orebody height under the condition of other parameters unchanged.It is concluded that when the buried depth increases,the maximum surface settlement gradually decreases until it finally remains stable.When the buried depth is 15 m,45m,75 m,105m,135 m and 165 m respectively,the hanging wall movement angles of grade III surrounding rock are 65.4 °,60.0 °,57.3 ° and 55.4 °,54.1 °,53.4 °,the moving angle becomes smaller and smaller,and the influence range becomes larger and larger,while the sensitivity of the moving angle to the change of buried depth becomes lower and lower,and the decreasing rate becomes smaller and smaller;The research on the depth ratio shows that there is a certain threshold for the depth ratio.When the depth ratio gradually increases and reaches the threshold,the maximum surface settlement and movement angle gradually remain unchanged.For example,when the depth ratio increases with the decrease of thickness,the maximum surface settlement gradually decreases and finally remains stable,and the movement angle gradually increases and the increasing speed is slower and slower.Similar simulation and numerical simulation are carried out for the mining of steeply inclined thick and large orebody with fixed maximum mining depth under the condition that other parameters remain unchanged.The similar simulation results show that when the maximum mining depth of steeply inclined orebody is fixed,the surface settlement changes greatly with the increase of burial depth.When the burial depth increases to a certain value,the impact of mining on the surface is almost negligible.The numerical simulation results show that when the maximum mining depth remains unchanged,with the increase of buried depth,the surface deformation value becomes smaller and smaller,and the surface settlement also shows a decreasing trend.The settlement center gradually moves towards the hanging wall,the movement angle gradually increases,and the increasing rate gradually accelerates.For example,when the buried depth is 15 m,45m,75 m and 105 m,the hanging wall movement angles are 58.3 °,60.9 °,65 ° and 74.1 ° respectively,and the buried depth is 135 m and above,Almost no impact on the surface.The settlement and stress data of numerical simulation and similar simulation monitoring points are derived and analyzed.It can be seen that the change trends of settlement and stress of the two monitoring points are basically the same.When the buried depth reaches a certain value,it has no impact on the surface settlement.The stress values of No.1,2,4,5 and 6 measuring points generally show a decreasing trend,indicating that the overburden rock and surface movement characteristics of the two simulation results are basically the same.