Study On Failure Mechanism And Control Technology Of Deep Surrounding Rock In Xishimen Iron Mine

The depletion of shallow mineral resources has forced mining activities to move deep into the earth.A series of technical problems brought by deep mining are attracting more and more attention.In this paper,the Xishimen iron mine is taking as the research background,facing the problems that he deformation and failure of the roadway is intensified and the difficulty of prevention and control is increased in the process of deep mining.The site investigation,lab tests,numerical simulation and theoretical analysis,are taking as combined research methods.Based upon the continuous-discrete coupling analysis model,the mechanism of deformation and failure of roadway under different confining pressure is revealed.The parameters of roadway support and blasting are optimized to ensure the safety and stability of roadway,realizing the safe transition from shallow to deep mining.This paper has achieved the innovative achievements as follows:(1)According to AHP principle and fuzzy evaluation theory,the hierarchical model of comprehensive evaluation on rock mass quality,which is improved for horizontal roadway,is established base upon lab tests.The stability characteristics of surrounding rock of-100m horizontal roadway in northern area are studied emphatically.The results show that the stability of rock mass will gradually weaken with the progress of mining downward.To-100m level,the upper surrounding rock evaluated as level 11 for roadway has changed into level ?.The mining depth and classification of the surrounding rock has a direct and important correlation.(2)Based on the continuous-discrete coupling analysis model,the stability of roadway surrounding rock is further studied and the research findings are as follows.With the increase of mining depth,the mechanical state of roadway surrounding rock gradually changed.With different confining pressure,horseshoe-shaped roadway rock gradually transition from elastic deformation to plastic deformation.Not only that,the destruction of the site also will change.When K is greater than 1,the surrounding rock damage is mainly concentrated in the roadway roof and floor.When K is less than 1,the surrounding rock damage is mainly concentrated in the roadway side walls.When K is equal to 1,the destruction of the surrounding rock shows obvious zonal disintegration.As the confining pressure continues to increase,the total number of ruptures gradually increases.(3)On the basis of the above research,the gray relational analysis method is used to optimize the parameters such as length,net degree and the installation angle of the rock bolts.Research shows that,in the case of the same degree of network,increasing the length of the anchor is appropriate with the increase in mining depth.While the rock bolt diameter and angle have little effect on the support effect.Accordingly,the corresponding parts of the support are designed.(4)The optimized parameters are applied in the North-100m horizontal roadway,and good support effect is achieved.Site monitoring results show that after the stability of surrounding rock,the roof sinking volume is control in the 15.2mm?16.8mm,an the side wall displacement is control in the 24.9mm?26.9mm.The optimized parameters such as peripheral eyeball hole spacing,minimum resistance line and cartridge diameter are 0.6m,0.67m and 25mm,respectively,which are better than the original design in the half hole rate and flatnessIn this paper,the following innovative research results have been achieved.(1)According to AHP principle and fuzzy evaluation theory,the hierarchical model of comprehensive evaluation on rock mass quality for roadway is established.(2)By constructing transfer algorithm and function of the continuous element and discrete element,a kind of continuous-discrete coupling analysis method for roadway is established and the macro-meso mechanical mechanism of roadway surrounding rock under different confining pressure is revealed.(3)Based on orthogonal test and Gray relational degree theory,a optimized method for rock bolt-mesh support parameters of roadway is established.The research methods and related achievements in this paper can partly make up for the existing the lack of the research work in the process of deep mining,and has a certain theoretical significance and engineering reference value.