Optimization of Filling Material Ratio in Goaf Based on Response Surface Method
In order to solve the problems of caving and gas diffusion in goaf,slag,fly ash and cement were selected as the aggregate,fine material and cementing agent of filling materials respectively.Response Surface Method(RSM)was adopted to design the matching test,and mass concentration,material proportion and slag particle size were taken as the single influencing factors.Material fluidity,compressive strength and permeability are the response target values.The effects of slurry mass con-centration,material proportion and slag particle size on the fluidity,compressive strength and permeability of filling materials are analyzed,and a nonlinear regression equation is established to optimize the ratio of filling materials under multi-objective conditions.The study results indicate that:① The volcanic ash effect of fly ash can affect the hydration process of filling mate-rials.As the proportion of fly ash increases,the compressive strength of each age group first increases and then decreases,and the permeability of each age group increases.② The surface of slag is rough and the density changes greatly.In the later stage of maintenance,as the particle size of slag increases,the compressive strength of the material first increases and then decrea-ses,and the permeability of the material decreases.③ The optimal material ratio for filling materials is cement:fly ash:slag=1∶3∶5,with a slurry mass concentration of 80％and a slag particle size of 5～10 mm.④ The flowability of the filling material under this ratio is 20.5 cm,and the permeability after 14 days is 0.021×10-14 m2,with a compressive strength of 22.2 MPa af-ter 14 days.The study results provide basic parameters and theoretical basis for the collaborative management of subsidence re-duction and gas storage in goaf.
filling materialsreduction of subsidence in goafcoal bed methane storagemechanical propertiespermeabil-ity characteristicsresponse surface method
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维普
