Microstructure Analysis And Simulation Reconstruction Of Gravelly Soil Based On CT Images

Different types of geotechnical materials are involved in engineering projects,and their macroscopic physical and mechanical properties are directly influenced by the pore structure characteristics.However,there are many geotechnical materials and the internal pore structure is very variable,so the problem of how to accurately simulate and reconstruct a geotechnical material under the condition of obtaining the microstructural characteristics of that geotechnical material remains to be solved.Based on the laboratory configuration of grade-deficient gravel soil samples,the pore structure parameters of the gravel soil samples were obtained,and the following conclusions were drawn for the simulated reconstruction of the gravel soil samples:（1）The pore structure parameters obtained in the laboratory do not differ much from the results obtained by Avizo software,and the permeability results of the three soil samples calculated by using the Poiseuille formula are:1.237×10^-3 cm²,4.839×10^-4cm²,6.936×10^-4cm²,and the permeability results of the gravel soil samples calculated by the Kozeny-Carman formula are:8.272×10^-5cm²,2.270×10^-5cm²,2.623×10^-5cm²,the comparison of the permeability results of the three soil samples shows that the accuracy of the results calculated using the Poiseuille formula is smaller than that calculated by the Kozeny-Carman formula,probably because the capillary bundle model used in the Poiseuille formula does not take into account the physical parameter of the tortuosity of the pore microstructure;（2）An important theoretical model in the study of geotechnical micro reconstruction is the overlapping sphere model,which is used to reconstruct porous media materials by randomly adding spheres with polydisperse radius R as pores to the porous media material model,and the Schultz distribution is used as the pore size distribution function.Assuming that all the pore radius parameters of the soil sample scanned by Avizo fit the gamma distribution,the Schultz distribution parameters of the sphere radii of the overlapping sphere system can be calculated based on the mean and variance of the gamma probability distribution function,and the linear path function of the soil sample pores is fitted to the linear path function of the pores of the overlapping sphere system with good results,indicating that the overlapping sphere theory can be used for soil sample reconstruction;（3）The conventional simulated annealing method mostly uses the two-point correlation function to reconstruct the soil sample model,on the basis of which the linear path function using the overlapping sphere system is added to reconstruct the soil sample,and the linear path function plots of the original soil sample slice,the random reconstructed soil sample slice using the original soil sample porosity and the reconstructed soil sample slice by simulated annealing are made,and the results show that the simulated annealing method adding the linear path function using the overlapping sphere system reconstructs the soil sample pore structure well.