Research On The Diffusion Law Of Grouting In Different Soil Media

Grouting engineering has a wide range of applications in the treatment of railway settlement,leakage compensation tunnels and rock filling caves,but in the current research progress,the practical application of grouting engineering is far ahead of theoretical research.Under the existing specifications,The grouting practice that guides on-site construction is still the grouting technical specification implemented in 1993.In actual field works,more workers use their own experience to reinforce the structures by grouting.Based on this,this article starts from the deficiencies and blanks of the current research on grouting,and uses the numerical simulation algorithm—CFD-DEM dynamic coupling calculation to carry out the numerical simulation analysis of the grouting engineering for the first time.The grouting test device has carried out model tests on the diffusion law of grout in the cohesive soil under different grouting pressures and single-row/double-row hole conditions.Through indoor geotechnical tests such as screening tests and direct shear tests,the grouting process has been explored.The changing law of the strength of the rock and soil before and after the solid.Finally,the study deduced the theoretical calculation model of the grout spreading area in sand,clay,breccia and other media,and verified and analyzed its correctness in combination with the indoor test results.The specific research conclusions are as follows:(1)A large-scale FLUENT-EDEM bi-directional coupled dynamic analysis technique was proposed,which can realize the dynamic fluid-solid coupling calculation of 600,000 particles.The diffusion evolution law of parameters such as the diffusion radius and the diffusion shape of grout in different rock and soil mass under different grouting pressures during grouting process was revealed.The results show that the diffusion radius in gravel soil is the largest,followed by sand.Minimum grouting radius of clay.The dissipation process of grouting pressure in the body.When the grouting pressure is low,the pressure dissipates quickly in the body medium.It shows that the grout diffusion radius is small in the macro sense.When the grouting pressure is high,the pressure dissipates slowly in the body medium.In the macro sense,the diffusion radius is large.(2)Independently designed and developed high-pressure porous grouting test device with adjustable pressure-flow rate,and carried out model tests of grout diffusion rule in clay under different grouting pressure and single row/double row hole conditions.The results show that the diffusion form of grout in rock and soil body is similar to petal type,and the reinforcement effect of double row hole on soil body in vertical direction is significantly better than that of single row hole.The shear strength of cement-soil mixture has been significantly improved.(3)The theoretical calculation model of grout diffusion area in sand,clay and breccia soil is derived,and its correctness is verified and analyzed by laboratory test results.The model can quantify the diffusion range of grout in different geotechnical materials under different pressures,and then determine the distribution range of grouting blind area.It can provide important technical support for optimizing grouting engineering design of high-speed railway and highway subgrade.