Study On Mining Method And Mining Stability Of Near-surface Broken Blind Orebody

There are many difficulties in mining near-surface broken orebody.On the one hand,the orebody is seriously broken and the stope is prone to instability.On the other hand,there are buildings on the surface,and the surface movement and deformation need to meet the requirements of the specification.In order to realize the safe mining of near-surface broken orebody,this paper takes the zinc orebody identified in Ashele Copper Mine as the research object,and adopts the methods of theoretical analysis,laboratory test and numerical simulation to carry out the research on mining method and mining stability.The main research work and conclusions are as follows :(1)Through the analysis of mining technical data and the investigation of the engineering site,the engineering geological conditions and mining status of the mine are expounded in detail.Statistics and analysis of drilling data near the zinc orebody,grasp the occurrence form of zinc orebody and rock characteristics of surrounding rock.(2)The physical and mechanical parameters of ore and surrounding rock are obtained by point load and indoor rock mechanics test of drilling core.The rock physical and mechanical parameters are reduced to obtain the elastic mechanics and strength parameters of rock mass,which provide basic data for numerical simulation.(3)The RQD spatial estimation is carried out based on the variation function theory,and the rock mass quality of the mine and surrounding rock in the mining area is graded according to the estimation results;The three-dimensional visualization results show that The ore bodies below 850 m are mainly grade III,and there are local grade IV.More than 850 m are grade IV to V rock masses,The quality of the surface rock mass is worse.(4)Aiming at the characteristics and difficulties of zinc orebody,based on the occurrence conditions of orebody,combined with rock mechanics experiments and rock mass quality classification results,the upward drift filling method,the upward horizontal layered filling method,and the sublevel drilling and sublevel drawing mining method with backfill are proposed.Through the comparative analysis of the miningcut ratio,mining technology,economic and technical indicators and safety and reliability of the three mining schemes,and using the fuzzy comprehensive evaluation method to optimize the mining scheme,the optimal mining scheme is determined.(5)Based on the determined mining scheme,the stope structural parameters are studied.FLAC3 D software was used to simulate the whole process of orebody mining and filling under different stope structural parameters.The variation characteristics of displacement field,stress field and plastic zone of surrounding rock and stope stability were analyzed,and the optimal stope structural parameters were determined.By calculating the influence of layered mining on surface stability,the reliability of mining scheme and stope structure parameters is further demonstrated.