Credibility Research And Stability Analysis Of Surrounding Rock Quality Classification Of Stope Roadway In Metal Mine

The stope roadway of metal mine is an important place for mine production.It is an important work for mine safety production to accurately classify the quality of surrounding rock of stope roadway and clarify the stability of surrounding rock of stope.In this paper,the surrounding rock of-230 m and-245 m horizontal stope roadway in Longdong mining area of Daye Iron Mine is taken as the research object.Through data investigation,field investigation and indoor experiment,the quality of surrounding rock of stope roadway is classified by RMR method,Q method and BQ method,and the quality of surrounding rock of stope is compared and analyzed.In view of the fact that the grades of grading factors in the RMR method are step-by-step and the scores of each factor are only simple mathematical operations to obtain the comprehensive grade of rock mass quality,which will cause a large difference between the comprehensive grade of roadway surrounding rock and the actual engineering situation,and some of the surrounding rock quality scores are located at the grade boundary,resulting in the problem of fuzzy rating.The credibility model of roadway surrounding rock quality classification based on entropy weight grey correlation and D-S evidence theory is constructed to evaluate the credibility of roadway surrounding rock quality classification results and improve the accuracy of classification.The stability of roadway surrounding rock is analyzed by the credibility results of roadway surrounding rock quality classification.According to the field situation of roadway surrounding rock and the classification results of loose circle surrounding rock,the applicability of the credibility results of roadway surrounding rock quality classification to the stability analysis of roadway surrounding rock is verified.The main conclusions are as follows :On the basis of field investigation,the quality classification of the-230 m and-245 m horizontal stope roadways in the Longdong mining area of Daye Iron Mine was carried out.The RMR classification was mainly grade II and grade III,the Q classification was mainly grade II,and the BQ classification was mainly grade III and grade IV.There are some differences in the classification results of the three rock mass quality classification methods,but on the whole,it shows that the surrounding rock quality of-245 m level roadway in Longdong mining area is better than that of-230 m level roadway,and the surrounding rock quality classification results of RMR method and corresponding support measures are more in line with the surrounding rock quality of roadway in this area.Based on the RMR method,a credibility model of roadway surrounding rock quality classification based on entropy weight grey correlation and D-S evidence is established.Considering the influence of qualitative and quantitative factors on rock mass quality classification,the credibility of roadway surrounding rock quality is evaluated for 19 typical measuring points in Daye Iron Mine.The results show that the model effectively integrates the credibility of each classification factor to the rock mass quality classification results.Some classification results are located at the boundary of the grade,which leads to the ambiguity of the grade determination,and accurately determines the classification results of the surrounding rock of the roadway.Based on the credibility results of surrounding rock quality classification,the stability of roadway is analyzed.The surrounding rock quality of-230 m and-245 m horizontal stopes in Longdong mining area of Daye Iron Mine is gradually improved from west to east,the stability of surrounding rock is gradually enhanced,and the support measures adopted on site are from strong to weak.The loose circle test was carried out in the area with general surrounding rock quality in the west of Longdong mining area.The results show that the quality of roadway surrounding rock is general surrounding rock.The classification of loose circle surrounding rock is consistent with the evaluation results of the credibility model of roadway surrounding rock quality classification,the stability of roadway surrounding rock and the supporting measures taken.