Back Analysis of Hydraulic Properties for a Landslide in the Three Gorges Area

Hydraulic properties of unsaturated soil are the key factors for reservoir landslide seepage analysis. The conventional method is mainly dependent on time-consuming, laborious, and expensive hydraulic tests. A methodology by back analysis was proposed in this paper according to real-time monitoring data of pore water pressure of No.1 Tangjiao Landslide in the Three Gorges area. A series of numerical simulation experiments were designed by orthogonal experiment theory. And the hydraulic properties in a Fredlund model were optimized and selected, which was a=10kPa, n=2.4, m=1.5, ks=0.5×10⁻⁶m/s. To validate the proposed method, the four parameters were taken as inputting hydraulic properties to simulate the landslide seepage with reservoir water fluctuation. And the range of relative error was -0.39% ~ 1.05% between the monitoring and simulated data. That proved that this back analysis method could be used as a feasible and effective technique for predicting hydraulic properties of landslide soils.