Stability Analysis And Evaluation Of Goaf Overburden Strata Caused By Shallow Seam Mining

Exploitation of shallow buried coal resources caused the surface deformation, cracking,not only destroyed the ecological balance of mining area, accelerated the process of soilerosion, but also cause serious damage to the ground facilities, and even induce massivegeological disasters.Therefore, the stability analysis and evaluation of the overlying strata ofshallow coal goaf has very important significance for disaster prevention and mitigation.Based on Nian Zi Gou mine as an example, this paper carried out the systematic research onthe shallow coal gob overburden failure law and overlying strata stability by using theoreticalanalysis, numerical simulation and engineering practice and other methods, through the datacollection, field investigation and goaf detection. The main work and achievements asfollows:(1) This paper studied the destruction rule of strata movement mechanism of shallowburied coal goaf from three aspects of destruction of roof breakage and overburden stratamovement and surface movement, and using ADINA finite element software to study thedifferent recovery rate, different mining width and different width of coal pillar under shallowgoaf surface deformation and stress distribution of coal pillar.(2) Using the catastrophe theory to mechanics of shallow buried goaf coal pillar-roofmodel for the stability analysis, obtain the mutation mechanism of the instability of thesystem, gives a shallow buried coal-the sufficient and necessary condition of roof systeminstability.(3) This paper analyzed the strata stability factors of shallow coal seam from threeaspects of the geological and hydrological factors, mined-out area characteristic parametersand other factors, and from the numerous factors selected16factors as evaluation index, established the shallow buried goaf stability evaluation index system, established thecomprehensive evaluation hierarchical structure model, using the analytic hierarchy process toanalyze the importance of each evaluation factor combination, determine the weight of theevaluation factors, constructed based on expert evaluation method and formula method ofmembership function, established the shallow buried coal seam goaf stability of the two stagefuzzy comprehensive evaluation model, the stability of Nian Zi Gou coal mine goaf wasevaluated. The evaluation results are basically consistent with the actual situation.