During the raining season in Taiwan, heavy rainfall often causes landslides, debris flows and collapses on slopes. The tie-back retaining pile method is one of the most popular methods used for slope rehabilitation. In the
past, the infiltration and seepage behaviors of slopes during rain fall have usually been ignored in the stability analyses. In this study, a large scale test on the infiltration and seepage behaviors of a slope is modeled using the three-dimensional finite element program, PLAXIS 3D, to validate and calibrate the numerical model. Then, a model of an unsaturated
slope consisting of a homogeneous layer of the colluvium was established for a series of slope stability analyses.
Meanwhile, the effects of infiltration and seepage behavior and the tie-back retaining pile system on the slope stability under different water table levels and rainfall patterns were investigated.
Key Words: Rainfall infiltration, tie-back retaining pile, slope stability, PLAXIS 3D.