The Seepage Evolution Characteristics in Undisturbed Loess under Dynamic Preferential Flow: New Insights from X-ray Computed Tomography

Preferential flow is widely developed in varieties of voids (such as macropores and fissures) loess areas, affecting slope hydrology stability even leading to geological disasters. However, the model seepage evolution with dynamic preferential not clear, which obstructs disclosure mechanism landslides induced by flow. This study aimed capture occurrence status water voids, explain variability characteristics pore structure, reveal infiltration experiments were conducted combining X-ray computed tomography (X-ray CT) nondestructive detection contrast techniques under conditions. Three-dimensional (3D) visualized reconstruction, digital image correlation (DIC), processing, quantitative analyses performed AVIZO 2019.1, including two-dimensional (2D) 3D distribution macropore changing, variation porosity, number, volume, dip angle, connectivity. Results showed that (1) exists saturated unsaturated conditions strong uniformity anisotropy; (2) only migrates into existing connected macropores, but also connects original isolated pores channels forms larger percolation groups medium gradually increased high pressure; (3) develops ‘preferential flow–piston flow–preferential piston mixture flow’ process. The new insights undisturbed will enrich understanding provided an important reference for future research on instability