Study On The Grouting Reinforcement Of Loess With Sodium Silicate And Cement Paste

The grouting method is widely used in the treatment of subsidence disease in loess project and the reinforcement of existing building foundation.For economic reasons,cement paste or sodium silicate is basically used as grouting slurry in loess engineering,and there are many experimental investigations about the effect of grouting,thus the effectiveness of cement slurry or sodium silicate to reinforce the loess is verified.However,there is a lack of mechanism research on the grouting in the loess and many problems in grouting engineering design needs to be solved.For this,relevant researches have been carried out based on the field test and theoretical analysis,original loess and remodeled loess are used as the medium and two kinds of single liquid of sodium silicate and cement paste are used as the grouting slurry,the relationship between the grouting pressure and the size of the slurry diffusion,the amount of grouting,the time of effective grouting and the time of grouting under each pressure are explored,the mechanism of the diffusion of two kinds of slurry in sodium silicate and cement paste is theoretically analyzed.The specific research results are as follows:1.This paper invents a set of field grouting equipment with practical value of engineering.,solving the shallow loess grouting hole sealing problem,designing the quality of real-time flow monitoring equipment,and configures the corresponding pipe equipment.Considering the characteristics of grouting reinforcement,the effective grouting time,the volume of soil volume per unit volume of soil,are puted forward to facilitate the description of cement and sodium silicate slurry grouting capacity.2.Based on the field grouting test,the difference of stone body formed by two kinds of slurry of sodium silicate and cement slurry is analyzed.It was observed that the cement slurry spread in the form of split and remolded loess in the form of remolding and original loess.With the pressure increasing to a certain extent,there would be large cracks in the two soils with the grouting radius increasing.The sodium silicate spreads mainly in the form of infiltration in the two kinds of soil.With the pressure increased to a certain extent,the split diffusion was found in the two soils,but the infiltration grouting was primary.Mainly.The relationship between slurry diffusion radius,grouting quantity,effective grouting time and grouting pressure is analyzed,and the changing rule of grouting volume with time under each pressure is analyzed.3.In the macroporous soil(including coarse grained soil),the cement slurry diffuses in the form of infiltration.Taking the large pore soil as the grouting medium and considering the filtration effect of porous media,on the basis of the steady state plane parallel flow theory and considering the influence of displacing the pore water or air with cement paste under pressure by the piston displacement,a physical model for cement slurry diffusion is established,and the relationship between cement front diffusion velocity,grouting volume and diffusion distance and time is also derived under the condition of the isobaric grouting according to the above physical model.4.The cement paste in the loess is diffused in the form of splitting,the split diffusion model considering the infiltration of free water in cement paste into the soil is established based on the experimental result.When the tensile stress in the soil exceeds the tensile strength of the soil,the fracture expansion occurs,combining the Poisson laminar flow equation,the elastic equation of the plane strain and the stress boundary condition of the crack tip,taking into account the infiltration effect of free water in the cement paste,the expansion equation of the linear main crack is obtained;the cement paste injected into the main crack compress the influenced,the elastic modulus of the loess is changed,the relation between the modulus change and the volume compression of the loess is deduced,and the expansion equation of the secondary crack is derived by the calculation method of the main crack.The split diffusion model and field test results of cement paste in loess are compared and analyzed,and the rationality of the model is preliminarily verified.5.The sodium silicate in the loess is diffused in the form of permeation.Based on the field test results and the the steady seepage theory,the physical model of the water glass diffusion is established by considering the influence of displacing the pore water or air with cement paste under pressure by the piston displacement;on the basis of the model,the relationship of grouting variables in the diffusion of sodium silicate in the loess is derived.Based on the steady state grouting model mentioned above,the unsteady state of the actual grouting process is considered,and the unsteady two-dimensional grouting model of the sodium silicate in the loess is further derived.The seepage diffusion model and field test results of loess glass were coMPared and analyzed,and the rationality of the model was preliminarily verified.