Seepage-Consolidation Deformation Characters of Sliding-Zone Soils under Water Level Fluctuation

During the water level fluctuation period of the Three Gorges reservoir area, the seepage stress coupling characteristics of the geotechnical body in the landslide have a great influence on the stability of the landslide. In this paper, a one-dimensional seepage test was conducted on the sliding-zone soil of Majiagou landslide. It tested the relationship between the seepage velocity of the soil and the hydraulic gradient and found the seepage characteristics of the seepage pressure p loading and unloading process. It also performed triaxial consolidation tests under steady-state and cyclical p and analyzed the effects of the confining pressure σ₃, the amplitude of the p, and the loading process on the permeability coefficient k and the volume strain. The following conclusions were drawn. (1) During the loading process, the seepage flow in the soil conforms to Darcy's law when the p was less than a certain threshold value, and the seepage flow shows nonlinearity when the p exceeds the threshold. The seepage flow conforms to Darcy's law when the p was unloaded. (2) When under a steady p, the k of soil is linear to the logarithm of the σ₃. Its instantaneous modulus influence coefficient decreases exponentially when the p increases. (3) When under a cyclical p, the k of soil decreased exponentially as the number of fluctuations increases. And a rebound effect of expansion and then compression appears in the specimens in each cycle. The rebound of accumulated deformation occurs at a certain time point, which is almost consistent with the threshold value in the fitting function of the k and the number of cycles under the same conditions.