Effect of long duration rainstorm on stability of Red-clay slopes

Background Slope stability issue in red clay slopes during rainfall is one among the serious geoenvironmental disasters in China. In order to investigate the effect of long duration rainstorm on red-clay slopes, studies were conducted using Geostudio 2012. Five different rainfall-durations were applied to the slope and the results of coupled and uncoupled calculation modes were compared. Results and Conclusions Results show that pore water pressure increased due to the dissipation of matric suctions and rise in water table during the rainfall period with the longer the rainfall duration, the larger the pore water pressure. The rate of change of pore water pressure was largest at rainfall durations of 4 days, among all the duration conditions considered for this study. After short duration rainstorms, a settlement of the surface of the slope was observed. However, in long duration rainstorms, the slope surface swelled in a non-uniform manner with the head of the slope experiencing the greatest expansion. Factor of safety exhibited a hysteresis during the calculation process, which was similar in trend with the pore water pressure as well, and it showed some amplitude during the calculation steps under the coupled calculation analysis as a result of the deformation and seepage force affecting each other on the performance of slope, especially for the slope stability.