Study On Stability Evaluation Of Goaf Of An Iron Mine In Liguo Town,Xuzhou

With the rapid development of mining cities and the acceleration of urbanization and industrialization,the value of the original abandoned goaf land resources is constantly improving,and more and more important engineering construction will inevitably occupy the goaf site.In order to promote the reuse of goaf land resources,it is necessary to make a scientific,reasonable and reasonable evaluation on the stability of goaf.Based on the analysis of the regional geological conditions of the study area,this paper summarizes the metallogenic background and deposit characteristics of the study area.Through comprehensive investigation and analysis,the engineering geological conditions and development characteristics of the study area are identified.The stability of the goaf is evaluated by using a variety of discriminant methods and FLAC numerical simulation,and the suitability of the goaf site engineering construction is evaluated by zoning.The survey results show that the thickness of the backfill layer on the goaf site is uneven,the overall engineering properties of the soil are poor,the bedrock surface is undulating,and the lithology and strength change,so the uniformity of the site foundation is relatively poor.There are two main goafs in the study area: abandoned pit left by surface mining in the southwest corner of the project construction area,which has been backfilled by miscellaneous fill;goaf roadway in the middle of the project construction area.According to the surface deformation characteristics of the goaf,the instability of the goaf is judged,the duration of the surface movement is calculated according to the empirical formula,and the stability of the goaf is judged according to the duration;the roof lithology and the thickness of the loose layer,the influence depth of the critical load and the "activation" analysis of the influencing factors are used to preliminarily evaluate the goaf as the unstable goaf.FLAC software is used to carry out the numerical simulation of goaf stability.Under the action of external load,the stress concentration of unfilled goaf roadway is more obvious,and it is easy to produce deformation and failure;the surface deformation difference is large,and the settlement is larger where the thickness of artificial accumulation layer is large,while the bedrock in the study area has higher stability because of no mining effect.The suitability of goaf site engineering construction can be divided into three types: I.poor suitability of engineering construction,and goaf has great influence on engineering construction;II.Basically suitable engineering construction,and goaf has medium influence on engineering construction;III.suitable engineering construction,and goaf has little influence on the proposed project.