Study On Development Regularity Of Fracture Zone Of Overlying Rock In Self - Propelled Iron Mine

Fractured zone height and shape show the degree overlying strata failure and disturbance range Induced by underground excavation, which is an important task of the study on the failure of overlying rock,and an important index of the roof stability management and water control. This paper,on Zizou Iron Mine of Xinping Ludian Mining Company (Pty.), Ltd., is to consider the fracture zone development and Influencing factors sensitivity in deep mining process of dip and high-deeping orebody.In this paper, the formation mechanism of "three zones" in overlying strata is firstly introduced, such as the development process, strength performance and main influencing factors. Then the upper bound of fractured zone is determined by using safety factor method,in combination with the yield criterion of Mole-Coulomb Model in FLAC3D. And then mechanical parameters of rock mass are determianted by Structural Plane Investigation and physical and mechnical tests. Finally numerical simulation based on finite difference method is carried out. The details are as follows:1) According to the need of numerical simulation, structural plane is investigated fistly, and physical and mechnical tests are done by using representative surrounding rock and ore. Then Hoek-Brown equation is used to reduce the the mechanical parameters of rock mass.2) According to the pillarless sublevel caving of Zizou Iron Mine, Orthogonal test of four factors and three levels is designed in the light of the development process, strength performance of fractured zone and main influencing factors. Then the FLAC3D models, established according to the experimental scheme, are excavated hop by hop, and Influencing factors sensitivity is comparatively analysed horizontally and vertically by SPSS.3) Simulation of single factor accroding to the two factors which significantly affect the fractured zone hight is carried out. Curve fitting is used to deal with the experimental results to analyse.4) According to the excavation height, orebody dip and horizontal thickness, the multivariate prediction functions of the height of fractured zone of the first and second stages are established. Finally the maximum height of each section is calculated based on geological sections.