Optimization Design And Experimental Research On Mix Proportion Of Wet Shotcrete In Mine

The use of shotcrete support in mine roadway has the advantages of reducing the dust concentration, reducing the rebound, improving the spray quality and supporting effect. It is of great significance to improve the working conditions of the mine excavation and support, to ensure safe and healthy production. However, there are the problem of blocking pipe in wet shotcrete during pumping, pipeline explosion and other serious threat to the safety of production problems. In addition,the dust concentration of wet shotcrete operation needs to be further reduced, in order to ensure the health of workers. These are very important parts of mine safety production work. Therefore, through the optimization design of mix proportion,and then get the wet shotcrete with small dust concentration and low occupational hazard during operationbetter pumping, better spraying and supporting. In this paper, the optimum mix proportion design of wet shotcrete is studied by means of theoretical analysis,experimental research,optimization of safety assessment method and field application.The effects of the type and amount of raw materials on the workability, the pumpability,the shootability,the dust analysis and economy of wet shotcrete were analyzed in detail. It not only gets the scope of the type and amount of raw material which is suitable for mix proportion design of wet shotcrete, and found five factors that affect the mix proportion design of wet shotcrete, such as water consumption, water cement ratio, sand ratio, accelerator amount and polypropylene fiber length. Design the orthogonal experiment of five factors and four levels in all the 16 groups, on the basis of ensuring the strength, liquidity for the slump,using slump to express fluidity, using pressured bleeding rate to express cohesiveness, using the pressure drop measured by the pump pressure experimental platform developed by our research group to express shootability. Through orthogonal experiment analysis, the correlation curves between the five factors and the properties of wet shotcrete were obtained,and the best ratio of the two groups of experiments was optimized from the 16 groups.The two groups of mix proportion were optimized to get the new mix proportion of the five groups, further study on the shootability, dust analysis and economy of wet shotcrete. The determination of the rebound rate, the determination of dust concentration and the calculation of the economy be tested separately, select the best three groups of mix proportion from the five groups of mix proportion. Using the analytic hierarchy process (AHP) in the safety evaluation method to select mix proportion accurately, the optimal mix proportion is the total target, and the shootability, dust analysis and economy are taken as the judgment layer, and the three groups are used for the theoretical analysis, according to the experience and the actual situation, we choose the importance of the three kinds of performance from large to small order as follows: shootability; economy; dust analysis. Through the analysis and comparison of the final selection of a set of optimal mix ratio.On the basis of the relevant experiments and analysis, field effect detection was carried out in a mine, to ensure that the technical conditions, the relevant characteristics of the injection parameters as well as the type of raw materials in the same conditions, respectively,according to the final selection of the mix proportion and the current use of the mix proportion of application to test the effect of the optimal mix proportion.