Study On The Stability Of Existing Ash Dams In Coal Mining Subsidence Area

This thesis takes an existing ash dam in a valley of Puxian County,Linfen City as the research object,and evaluates the feasibility of coal mining under the dam and the stability of the ash dam.A mechanical parameter inversion method based on the surface soil samples of the ash dam is adopted to determine the physical and mechanical characteristics of the ash dam fillings,and numerical simulation is used to analyze the displacement change,slope stability and seepage stability of the most unfavorable position of the ash dam under the disturbance of mining under the dam and rainfall intensity of 0.73mm/h for 120 h,and then evaluate the overall stability of the ash dam.Based on the analysis results,corresponding engineering countermeasures and suggestions for ash dam reinforcement and seepage prevention design are proposed.The specific research results are as follows:1.The research results of the safety and displacement law of the ash dam under mining influence show that mining under the dam is feasible.The maximum horizontal displacement is 10.84 mm,and the maximum vertical settlement is-31.27 mm,both showing asymmetric distribution;The safety factor of the most unfavorable position of the ash dam is 1.5765,which meets the specification requirements.2.The maximum total water head and maximum pore water pressure of the ash dam under continuous rainfall are calculated to be 34.68 m and 64.11 k Pa respectively;The safety factor of the most unfavorable position under continuous rainfall condition is 1.70,and under the dual influence of rainfall and mining is 1.4769.The stability of the ash dam is good and no reinforcement treatment is needed.3.Based on the analysis of the comparison between the infiltration line after continuous rainfall for 120 h and the initial state,engineering suggestions such as setting drainage pipes at the toe of the first-level sub-dam and #5 characteristic point,setting vertical or horizontal seepage prevention facilities on the upstream side of the ash dam are proposed.The thesis has a total of 33 pictures,17 tables,and 90 references.