One of the hot topics in the study of rock and soil hydraulics is the size effect of a soil–rock mixture’s (SRM) seepage characteristics. The seepage process of the SRM was simulated from the pore scale through the lattice Boltzmann method (LBM) in this paper to explore the internal influence mechanism of sample size effect on the SRM seepage characteristics. SRM samples were generated using the improved Monte Carlo method (IMCM), and through 342 simulation test conditions the influence of size feature parameters such as resolution (R), segmentation type, model feature size (S), feature length ratio (F), and soil/rock particle size feature ratio (P) was examined. The study demonstrated that as R increases, the permeability of the SRM gradually rises and tends to stabilize when R reaches 60 ppi. At the same S, the dispersion degree of model permeability obtained by the four segmentation types is in the order of center < random < equal < top. With an increase in S, the permeability (k) of the SRM gradually decreases, conforming to the dimensionless mathematical model, k=a0·S−b0, and tends to stabilize at S = 80 mm. With an increase in F and an increase in S, the permeability of the SRM exhibits a linear “zonal” distribution that declines in order. When F is greater than 12, the dispersion of the permeability value distribution is especially small. With an increase in P, the permeability of the SRM decreases gradually before rising abruptly. P is crucial for the grading and structural makeup of the SRM. Overall, this paper concludes that the conditions of R = 60 ppi, center segmentation type, S = 80 mm, F ≥ 12, and P set by demand can be used to select and generate the size of the SRM optimal representative elementary volume (REV) numerical calculation model. The SRM can serve as a general reference for test and engineering construction as a common geotechnical engineering material.
To reveal the dynamic seepage mechanism of water-gas two-phase in soil, the undisturbed granite residual soil in Fuzhou was selected as the research object. Based on the computer tomography(CT) image and AVIZO-COMSOL interactive docking technology, the Level Set method was used to study the 3D water-gas two-phase seepage characteristics of the undisturbed granite residual soil at the REV scale. The results show that the residual gas in the pores is mainly distributed in blocks on the pore edges, dead corners and sudden changes of pore throats. Among the numerous pores of the REV model, there are only a few major seepage pores, which are generally characterized by wide and straight pores. In different seepage stages, the velocity distribution is different. In general, the flow velocity increases first, then decreases, and then gradually increases. The maximum velocity growth rate and decrease rate are 61.04% and 40.60%. With the increase of seepage time, the saturation of the water phase shows a sharp upward trend, and the saturation of the gas phase shows a sharp downward trend, they both occur in the initial stage of seepage, and then gradually tend to be stable. Finally, the saturation of the water phase and the residual gas phase tend to 91.86% and 8.14% respectively.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.