Study On Roof Stability Of Stope In Soft And Hard Rock Stope

The stability of the roof in the goaf is an important prerequisite for safe mine production.When the top rock mass of the stope mined in the local area is composed of layers of soft and hard rocks with different strengths,the problem of instability of the goaf caused by roof deformation and destruction is The key to mine safe mining,the use of theoretical analysis,numerical calculations and other methods to study the law of the stress and displacement changes in the mining of soft and hard rock roofs,in order to analyze the stability of the roof.The roof of the strata in the strata can be divided into five types: hard rock,soft rock,soft rock sandwich body,hard rock sandwich body,and soft and hard rock interbed body.The top plate of soft and hard rock interbedded body is selected as the research object.The structural features of the rock masses with different intensities of soft and hard rock alternately appear,and the rock masses may intersect at a certain angle.Based on the theory of Reissner slab,the top plate of the soft and hard rock interbed stope was reduced to a three-dimensional strain plate,and a mechanical analysis model of the stope roof was established.Combining the knowledge of the elastic mechanics plate theory and the bending mechanics of the material mechanics,the support and support were deduced.The deflection curve equation of the roof of the stope is simply supported,and the maximum displacement and stress analytical formula of the roof are obtained;that is,the maximum displacement and the maximum stress of the roof,the top load,the elastic modulus of the rock mass,the Poisson's ratio,the thickness of the roof are established.The relevant equations for the main factors such as the size of the roof and the mining of the roof.Combining the maximum displacement and maximum stress analytical formula of the top plate,the maximum displacement of the top plate and the maximum stress along with the length and width of the top plate,the length and thickness of the top plate,and the three-dimensional curve of the mutual change are plotted using Matlab software,and the top plate can be obtained from the graph.The maximum displacement and the relationship between stress and single factor,as well as the interaction of the two factors on the maximum displacement and stress of the roof.Based on the geological conditions of typical hard and soft rock mining in a certain vanadium mine in Jiangxi Province,a FLAC3 D numerical simulation model of rock formations in soft and hard rock interbeds was constructed.Three types of mining schemes were designed.Through simulated excavation of rock formations,they were obtained at different depths.,the different mining thickness,and the variation rule of stress and strain of the roof under different mining size ratios;the research results show that the mining size of the roof,the thickness of the roof and the depth of burial do have an important influence on the stability of the slab,and its influence relationship is related to The sexual effects are identical to the conclusions obtained in Chapter 4,thus validating the feasibility of the Reissner plate theory.