Research On The Development And Engineering Characteristic Of A New Cementitious Filling Material

China is rich in coal resources.With the development of coal mining intensity,the mining depth is increasing,the speed of mechanical propulsion is fast,the working face is long,and the coal body is easily disturbed,which makes the safety accidents of coal mining happen continuously.The deeper the coal mining depth is,the worse the coal seam occurrence condition is and the higher the gas content is.However,coal mine air leakage is the main cause of gas accumulation,which leads to gas mine accidents.In order to reduce gas safety accidents in coal mines,avoid gas leakage,and prevent coal mine fire caused by gas.It is very important to develop a new type of cementitious filling material with low cost,environmental protection,plugging,sealing,compression resistance and good expansion effect.Based on the research background of coal mine gas treatment,this paper analyzes the problems of filling materials used in gas treatment.In order to improve the filling effect of the filling material,foam is introduced into the inorganic filling material to change the performance of the filling material.Based on expansive cementitious backfill material,the formation and stability mechanism of foams and the mechanism of foam formation were studied in this paper.Through single factor analysis and orthogonal experiment,the influence of each component of filling material on its performance was studied,and the filling effect of filling material was simulated with COMSOL numerical simulation software.The main work and research results are as follows:(1)Stability of foam and reaction mechanism of main materials.By analyzing the relationship between the surface tension and foam,and the relationship between surfactant and foam,the principle and process of foam generation,and the conditions and failure mechanism of foam production are obtained,which is of guiding significance for the preparation of foam and the stability of foam.The mixing of foam and cement slurry mainly changed from "gasliquid interface" to "gas-liquid solid interface",and "gas liquid solid interface" to "gas solid interface transition".Finally,three stages of gas solid interface were formed,filling material with stomatal structure was formed,which lay a foundation for subsequent expansion cementitious filling material preparation.(2)Test and analysis of the optimal ratio of expansive cementitious filling materials.The effects of water cement ratio,foam content,water reducing agent and water glass content on the properties of expansive cementitious backfilling material were studied by single factor analysis and orthogonal test.The optimum ratio of foam permeability(0.5L),water cement ratio(0.40),water reducing agent(0.4%)and water glass(0.5%)was the best proportion when dry density was used as evaluation index.The ratio is foam content(2.0L),water cement ratio(0.55),water glass(1%),water reducing agent(0.40%).(3)Study on permeability of filling material and its application by numerical simulation.The influence of gas permeability of filling materials on gas migration is analyzed by numerical simulation.Based on the gas migration in large space goaf with high strength and rapid advance,the gas migration law under different control modes is studied.In this paper,there are 43 figures,23 tables,and 100 references.