Study On Dynamic Response Of Suspended Stope Floor

Taking backstopping of mine's residual ores lying above stopes in the open-stope condition as engineering background, comprehensively applying numerical simulation and theoretical analysis methods, this paper gives a research on characteristics of dynamical response of stope floor when subjected to impact of massive caved rock and hopes to draw some beneficial results, these results can be regarded as an explorative and assistant job for the recovery technology of residual ores which are hosted above stopes.The main research works are as follows:(1)The dynamic mechanical properties of rock derived from mine was tested by using improved SHPB equipment. In the test research, the characteristics of rock's deformation, fracture and energy dissipation were investigated when the rock was subjected to different impact loading rates, confining pressure and cyclical impact loading. At the same time, for the sake of subsequent numerical simulation, the dynamic physical and mechanical parameters, such as deformation modulus and peak strength of siliceous limestone were obtained.(2)The micro-parameters calibrating of PFC rock material. Because of the unique characteristics of particle flow method, it is necessary to adjust the micro-parameters between particles so that macroscopic mechanical response of particle assembly is in accordance with that of real rock material. For this reason, a virtual test platform composing of uniaxial compression and SHPB was established, in this test platform, PFC specimen composing of particle was tested, and the PFC materials micro-parameters which were expected were obtained.(3)Through using the PFC based on discrete element method, the characteristics of dynamical response of stope floor when subjected to impact loading was studied. The rule of transition and distribution of impact loading and the formation and evolution of cracks in the rock beam and surrounding rock was analyzed, furthermore, the influence of factors, such as different forms of impact loading, squeezing action from surrounding rock and fracture surface on characteristics of dynamical response of stope floor was also investigated.(4)According to project actual situation, numerical model composing of stope structure, ores cushion and caved rock was established, by using this model, the mechanical relationship between stope floor and ores cushion subjected to impact loading was investigated, meanwhile, the effect of ores cushion's microscopic and macroscopic parameters such as distribution of particle size, friction coefficient and thickness of ore cushion on damage properties of stope floor was also studied so as to obtain the cushioning mechanism of ores cushion.(5)The catastrophic model for dynamic buckling and fracture of stope floor which contains fracture surfaces was established, using this theoretical model, non-linear evolution of stope floor induced by caved ores was analyzed.