"Activation" And Stability Evaluation Of Mined Out Area Under Railway Load

Our country continue to increase investment in infrastructure construction in urgent need of goaf under load "activation" rules and evaluate the stability of the in-depth study,especially some major ground transportation engineering construction can not be around mined out area,mined area makes the ground construction face extremely serious hidden danger of geological disasters.This problem is particularly serious in many coal mine in China and has a wide distribution area of small coal mines.This paper focuses on the "activation" and stability evaluation of mined out area under the load of railway trains,which is of great practical significance and engineering value to ensure the safety of railway operation.On the basis of a large number of domestic and foreign literatures,this paper combines the theory analysis,numerical simulation and field monitoring method to study the engineering example of a certain railway.First,summarizes the characteristics of goaf,analyzes the factors of goaf evolution process,influence of goaf stability and activation mechanism;secondly,using field monitoring and finite element simulation software of train dynamic loads in goaf was simulated to calculate the 3-D numerical analysis.Empty area "activation" movement and deformation and influence factors of stability under different conditions;finally,based on the analysis of factors of mining goaf stability,the stability evaluation of goaf in mining stability evaluation as well as further railway loading method considering.The main contents of the study are:1.According to the relevant literature,summarized the basic characteristics of goaf and the harmfulness of the mining,process change and strata movement after mining mining process are analyzed,the influencing factors of the stability of mined area,explains the goaf in the external load by further activation mechanism.2.By using the finite element numerical simulation software,simulated the effect of railway load of goaf under "activation" process,comparative analysis of the three conditions of the goaf "activation" movement and deformation law and influencing factors of stability.It is considered that the influence of railway load mainly has the following characteristics:(1)The displacement response caused by railway dynamic load has obvious time history characteristic and three dimension characteristic;(2)The railway train passing through the goaf,affect the gob "activation",the gobsurface subsidence,then,with the railway train through the reciprocating goaf,the goaf subsidence of "activation" continue to accumulate,influence the stability of goaf,affect the safe operation of the railway;(3)When the railway load is applied,the influence of the vertical additional effect is larger than that of the left and right;(4)The impact of railway load on the surface has certain advance and lag behind,the railway train running in front of a certain range will be affected by the surface deformation,load effect,when the train running away,the surface deformation effect before the end of;(5)Under the same geological condition,the load on the formation of the railway has a certain fluctuation.The fluctuation frequency of the far position is low,and the more close to the mined out area,the more dense the disturbance is;(6)When the railway line is located above the mining area,the dynamic load of the railway is the largest value added to the mining area.3.Construction of a variety of evaluation methods of comprehensive weight based method,reducing the subjective factors caused by weight deviation,and the discrete and continuous variable factor analysis,established two fuzzy comprehensive evaluation model of goaf stability.4.Combined with an engineering example,this paper analyzes the results of this study.