Research On Physical And Mechanical Properties Of Desert Sand Grouting Material In Goaf And Its Application

Northwest my country is rich in desert sand,and there are many coal mines in these deserts.The geological mining conditions of the coal mines are poor,and most of the reserves need to be mined by well workers,resulting in more goafs.Aiming at the characteristics of desert sand with finer particles,large specific surface area,and difficulty in mixing,this paper carried out an indoor mixing ratio experiment of desert sand grouting materials in the goaf.Relying on the existing goaf treatment project under the expressway,the desert sand grouting material is used to carry out the grouting treatment design for the existing goaf.Use FLAC3 D software to establish a goaf grouting treatment model,and analyze the surface settlement before and after grouting reinforcement in the goaf.The main research contents and results of this paper are as follows:(1)Analyze the physical properties of desert sand,in order to grasp and understand the characteristics and basic properties of desert sand,so as to facilitate more accurate design of indoor mixing ratio experiments of grouting materials.The particle density of desert sand is 1.63g/cm3,the moisture content is 3.42%,and the particle size is mostly below 0.1mm.The uneven coefficient of desert sand u<5,the coefficient of curvature c≈1,and the gradation is poor.(2)Indoor proportioning test of desert sand grouting material to study the influence of waterbinder ratio,glue-sand ratio,and fly ash content on the viscosity,fluidity,stone rate,water separation rate and compression resistance of the desert sand grouting material The impact of intensity.Through pre-experiment,an orthogonal scheme design was carried out,and the test was carried out at a factor level of 0.8:1～1.0:1,glue-sand ratio 2:8～4:6,and fly ash content of15%～25%.Through the analysis of the test results,it is concluded that the optimal ratio of desert sand grouting materials is: water-binder ratio 0.8:1,rubber-sand ratio 4:6,and fly ash content 25%.(3)Relying on the engineering example of the existing goaf governance problems under the Urumqi expressway,the design plan of grouting construction in the goaf was proposed,and the simulation verification was carried out through FLAC3 D software.The optimal ratio of desert sand grouting materials and the treatment length,treatment width,treatment depth,grouting volume,drilling layout and other related parameters of the grouting treatment in the actual project are determined.The simulation results show that the desert sand grouting material has a good effect on the grouting control of the existing goaf under the expressway.The desert sand grouting filling material studied in this paper has applicability.