Optimization Research Of Non-pillar Sublevel Caving Method In An Iron Mine

This paper is aimed at researching the structural parameters of non-pillar sublevel caving,poorly effective of medium-length hole blasting and the difficult technical problems of roadway supporting in an iron ore.In it,comprehensive research methods are adopted,which are theoretical analysis,field investigation and laboratory experiments.This paper has strong pertinence,and the main results are as follows:(1)In accordance with the investigation of engineering geology,joint orientation mainly concentrated in the SW 50° to SE 70°,which is consistent with the main mining area faulted structure and the joint strike direction.Those results indicate the close activities of faults and the joints causes within the district.(2)The rock mass quality of the mining area is classified in this paper based on the RMR method and rock mechanical tests.The results are: the levels of the ore body and surrounding rock are the third grade;the rock mass is of average quality.(3)The structure parameters of the iron ore is recommended with 20 m ×18m ×4m(sublevel interval height × cross-cut drift spacing × ore caving step)through a series of physical simulation experiments,combined with the theoretical analysis.(4)The blasting parameters recommends that each blast-hole layout has 9~10 holes,the bore diameter is of 76 mm,hole bottom distance 2.9 m ~3 m,row spacing 2 m,and the row surface angle is of 85°according to the research of medium-length hole blasting and a series of fan-patterned blasting experiments.What's more,the blasting parameters should be millisecond delay in hole-by-hole,and an indirect priming among the holes.(5)Based on the classification of rock-body quality of mine and the analysis of blasting effects,this paper puts forward some technical measures about roadway excavation and supporting.First of all,the tunnel smooth blasting technique should be adopted where possible when roadway is excavated.Then,the surrounding rock should be supported by sprayed concrete as soon as possible.After that,according to the condition of surrounding rock,technical personnel ought to determine whether the second spraying has to be supported or the rock bolt should be constructed after the second spraying support.Secondly,the investigation of engineering geology should be enhanced so that the supporting measures can be adopted flexibly.Last but not least,in order to ensure the construction quality,specialized implement had better be purchased.