Investigation of porosity control methods and orthogonal testing of coal-similar materials
Coal-similar materials form the foundation for simulating tests.Porosity significantly impacts the generation and movement of coal seam gas.Currently,the similarity of porosity is often overlooked in materials used for simulating coal and gas outbursts.By incorporating porosity control materials into the raw materials,it becomes possible to regulate the porosity of the similar materials by leveraging their inherent volatilization or melting characteristics.In this study,camphor particles were chosen as the porosity control material for coal bodies.To account for the impact of various factors such as camphor particle gradation,camphor particle mass fraction,molding pressure,and cement mass fraction,an orthogonal design method was employed.This method facilitated the execution of an orthogonal matching ratio test on similar materials with four factors and four levels.Consequently,16 similar material specimens were meticulously prepared.Subsequently,each specimen was subjected to testing to determine the porosity,firmness coefficient,initial velocity of gas emission,and permeability parameters.By conducting variance analysis and multiple linear regression analysis,the quantitative relationship between the influencing factors of the similar materials and the simulation indexes was established.Furthermore,a multiple linear regression equation was derived to demonstrate the relationship between these factors.Building on these findings,the ratio of similar materials for coal samples in the outburst coal seam of Linsheng Coal Mine was determined and confirmed through experimentation.The results indicate that camphor particles are better suited as porosity control materials compared to dry ice particles.The mass fraction of camphor particles exerts a significant influence on the material's porosity,while the particle gradation has a minor effect.As the mass fraction of camphor particles increases,the porosity of similar materials also increases.The specimens prepared using the porosity control method with camphor particles exhibit favorable similarity to the firmness coefficient,initial diffusion velocity,and permeability of raw coal samples.These results demonstrate the feasibility and effectiveness of the porosity control method employed.
safety engineeringsimilar material for coalcamphor granulesporosity controlorthogonal test
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