Effect of seepage-induced erosion on soil macropore structure

Internal erosion is one of the important factors causing geological disasters. The microstructure of soil can change with seepage erosion, resulting in changes in the hydraulic and mechanical properties of the soil. The evolution of seepage erosion is investigated with X-ray computed tomography (CT) in this study. The change in macropore structure characteristics during the seepage erosion test is quantified and the influence of seepage erosion on soil deformation is analyzed. Moreover, a pore network model (PNM) is established for the specimens and the evolution of the connected pore size characteristics is assessed. The results show that the macropore structure is significantly affected by seepage erosion, especially in terms of the porosity and pore geometry characteristics. The changes in macropore structure characteristics are most obvious in the lower part of the specimen. The influence of seepage erosion on the pore size distribution (PSD) and soil deformation is heterogeneous and closely dependent on the spatial location of the soil. Moreover, seepage erosion enhances macropore connectivity and has a directional impact on macropore orientation. These findings can provide a reference for the theoretical modeling and numerical simulation of the seepage erosion and improve the understanding of the seepage erosion evolution in engineering practice.