Study On Stability Of Mined-out Area In Shilei Tungsten Mine

The shrinkage method is the most effective mining method for mining steeply inclined thin orebody,but when the mining work is completed,a large number of mined-out areas will be left behind.If the mined-out areas are not dealt with in time and reasonably,with the gradual increase of ground pressure,large-scale instability of mined-out areas may occur,resulting in huge loss of resources,and even the safety of production personnel in danger.Therefore,it is of great significance to study and analyze the stability of mined-out areas and determine the economic and safe treatment scheme of mined-out areas for ensuring safe production of mines.by means of field investigation,theoretical analysis,field monitoring and numerical simulation,this paper studies and analyses the stability of goaf in 43-47 line production area of Shilei tungsten mine northern zone,and simulates,filling treatment of goaf with FLAC3 D software,and obtains an economical reasonable treatment scheme of goaf.The main research contents are as follows:(1)Through onsite investigation and mine geological survey report,basic informati on such as the distribution,scale and shape of minedout areas in mines can be underst ood and grasped.(2)The rock mass is sampled and processed into specimens.The mechanical para meters of rock mass are measured by experiments.Then the generalized HookBrown criterion and elastic wave method are used to modify the reduction,and the mechanic al parameters of rock mass are obtained.(3)The instability mechanism of pillars and roofs in goaf is analyzed by using structural mechanics theory,and single pillar is calculated.The ultimate span of the short side of the goaf is 6.9 meters,the ultimate span of the short side of the goaf is 43.6 meters,and the safe width of the pillar is three meters.(4)Establish a three-dimensional model and use FLAC3 D software to carry out numerical simulation excavation of the mine.According to the stress,displacement and expected area cloud map of each middle section obtained after simulation excavation,the stability of the goaf is analyzed.The analysis results show that with the decrease of mining depth,the stress,displacement and plastic area of the lower goaf increase gradually,but most of the goaf has not yet reached the instability dilemma,and some of the stress concentration in the goaf.Larger wast rock is used to fill the goaf.Compared with the stress nephogram before and after filling,the stress of the goaf is obviously redrawn,which can provide a reference for selecting the treatment method of the goaf.(5)The photoelastic stress meter and convergence instrument are used to arrange monitoring points in the surrounding rock and roadway of the empty area to monitor the stress of the surrounding rock and the displacement of the roadway section.The monitoring results show that the mined-out area is relatively stable on the whole,but the stress concentration in the local mined-out area and the ground pressure is obvious.