Stability Study On Underground Stope Structure Based On Finite Element Limit Analysis Method

Abstract:The safety factor is a key problem for designer. Combined with "the study of Shaxi copper deposits’mining method selection and parameter optimization of ore block structure" research projects, a new method to calculate the general safety factor of Underground stope structure was put forward, which was based on the finite element limit analysis method. The main contents are as follows:(1)The system investigation work had been done.The work include the status quo of underground stope stability analysis and finite element limit analysis and the the principles of finite element limit analysis method for solving geotechnical stability.(2)Based on numerical experiments, the underground stope structural stability limit analysis method was proposed. According to practical experience, taking the pillar shear instability and a large area of roof caving instability as the overall instability measure of the stope structure measure in the numerical experiments. So proposed the transfixion of plastic strain in pillar and large area transfixion of plastic strain in roof and the mutation of key points displacement, total volume of the destruction unit and maximum plastic strain as the critical failure criterion to get the safety factor and then evaluate the stability.(3)According to the Shaxi copper mine orebody occurrence conditions, as well as surrounding rock characteristics of roof and floor engineering geological conditions, selecting typical rock samples on site and doing experiments to study rock physical and mechanical properties.(4) According to the engineering geological investigation and rock mechanics test results, utilizing finite elemen limit analysis method, using FLAC3D numerical simulation software to establish the three-dimensional model.By continuous reducting mechanical strength parameters of rock mass shearing value, according to the proposed overall instability criterion, seeking stope structure’s overall critical instability criterions of Tong Quanshan ore block to determine its critical state, and to get the overall safety factor. The results show that the design recommended stope structure has good stability and the method can be used for quantitative evaluation of the overall security of the underground stope structure.(5)The stope structure parameters were optimizated based on the finite element limit analysis method for deposit mining design.