On Mechanical Stability Of First Base In Caving Process Of Longshou Lean Ore Mining Area

Based on fieldwork and investigation in existing research results of geological conditions, geological structure and rock mechanics nature in the ore mining area, this paper summed up key mechanical problems that may appear in the caving method and carried out the corresponding mechanical simulation calculation.The caving simulation include two parts: the first part establishes the two-dimensional finite element model according with the actual mining history evolution process to study the stress concentration, which called as "stress packets ", in the closed mine roof at the bottom of open pit formed by the early open pit mining and subsequent underground mining, which is consistent with the continuous ridgy characteristics at the bottom of open pit. The second part simulates the mining process of the caving method with the established three-dimensional finite element model, and find that the stress field of the bottom structure are significantly affected by the original "stress packets" characteristics and the subsequent caving process, from which it is obtained that the spatial and temporal law of the stress and the deformation at the bottom structure during the continuous enlarging process of caving area.Research results provide a theoretical guidance for the optimal design of the bottom structure in the future caving mining.