Temporal variation in the permeability anisotropy behavior of the Malan loess in northern Shaanxi Province, China: an experimental study

By analyzing a fresh soil section and soil samples from Yan'an New Area, northwest China, an engineering shallow loess slope was investigated. Temporal variation in the saturated horizontal hydraulic conductivity (K_h) and saturated vertical hydraulic conductivity (K_v) of loess samples were measured using variable head permeability tests. The K_h and K_v values indicate that the loess exhibited permeability anisotropy in space and time, and K_h and K_v at different depths decreased as seepage time increased. K_h-time showed an exponentially decreasing trend, and K_v-time showed a linearly decreasing trend. Analysis of the initial state and micromorphological features of the loess indicate that the orientation of soil particles in the deposition process may be inherently anisotropic. The K_h and K_v values of the loess tended to decrease with depth, as described by an exponential decay model.