Study On Sealing Characteristic Using New Inorganic Retarded Sealing Material For Gas Drainage Borehole

Gas extraction is a valid way to reduce gas disaster that appear in the process of coal mining.Sealing technology is crucial for efficient gas extraction.Thus,choosing a suitable sealing material can guarantee the long-term and efficient gas drainage.Based on learning from previous experience,this paper raises the idea that is sealing with liquid materials.Through material selection and performance test,laboratory device design and material diffusion performance test,discrete element numerical calculation,the grouting performance,seepage mechanism and application of new inorganic retarding sealing materials are studied.First of all,this paper introduces a new type of inorganic retarding sealing material and tests its various properties.Through analyzing the main ingredients and the functions of all kinds of ingredients in the new type of inorganic retarding and sealing materials,all tests are designed to test its fluidity,water evolution rate and permeability in different water cement ratio conditions.The application range of water cement ratio of the new type of inorganic retarding and sealing materials is 8:1,9:1 and 10:1.The grouting time of the above three kinds of water cement ratio grout was tested,which were 12.5min,23.2min and 35.9min respectively.Through testing the grouting of the above three kinds of water cement ratio slurry and the stability and thermal stability of the material we can conclude that the material had excellent stability and thermal stability.Finally,the influences of portland cement,fly ash and sodium triopoly phosphate on the properties of the new inorganic retarding sealing materials are analyzed quantitatively.Secondly,the diffusion process and pressure distribution of the new inorganic retarding sealing material slurry under different conditions were investigated.Test pressure at different points in the process of slurry diffusion under different conditions,through the design of fracture grouting test system.Different fracture width,different fracture opening,different fracture angle and different bending angle is tested,and the pressure distribution in the process of slurry diffusion under these conditions is obtained.Through the design of slurry plane diffusion test system,the slurry diffusion and grouting pressure changes under the same water cement ratio and different crack opening conditions,as well as the slurry diffusion and grouting pressure changes under the same crack opening and different water cement ratio conditions are tested,and the slurry diffusion law and grouting pressure change law under these conditions are obtained.Thirdly,the seepage of slurry in the coal and rock mass around the sealing section of gas drainage borehole is further studied.The numerical model of drilling grouting is built by FLUENT software,and the diffusion rule and pressure change of new inorganic retarding sealing material under different grouting parameters are simulated.It is proved that the range of slurry diffusion to the lower part is substantially larger than that to the upper part with the less grouting pressure.The influence of slurry gravity on slurry flow decreases,when in the high grouting pressure.In the Initial stage of grouting,Diffusion radius of pore slurry expands rapidly with the increase of grouting pressure.But in the latter stage of grouting,Diffusion radius of pore slurry have a small change with the increase of grouting pressure.By analyzing the pressure changes in the process of slurry diffusion under different grouting parameters,it is concluded that the pressure distribution of three kinds of water cement ratio slurry in the coal and rock mass around the borehole is significant difference under the condition of small grouting pressure.As the grouting pressure increases gradually,the difference of the pressure curve of the three kinds of water cement ratio slurry in the surrounding rock decreases,and the coal around the borehole is analyzed under various grouting pressure conditions at different grouting times the distribution of internal slurry pressure.Finally,the new type of inorganic retarding sealing material proposed in this paper has been tested in 21109 working face of Henan Energy City suburb coal mine.The results show that:according to the field test design of the conclusion of this paper,during the two-month observation period of gas drainage,the gas concentration of the drilling holes sealed with new inorganic retarding sealing materials is always greater than 30%,and the gas extraction purity is always above 0.12m~3/min,compared with the drilling holes sealed with polyurethane and expansion cement,The pumping effect is good.There are 53 figures,9 tables and 88 references in this paper.