Back Analysis of a Recent Progressive Failure in China Three Gorges Reservoir Area: Shanshucao Landslide

The Shanshucao landslide is a recent landslide that occurred in the China Three Gorges Reservoir area. It is next to the Daling Hydropower Station landslide, one of the geological hazard professional monitoring points in the China Three Gorges Reservoir. The Shanshucao landslide had not shown a significant deformation during recent decades until September 2nd, 2014. On that day, the Shanshucao landslide abruptly started to move at around 9 a.m. local time, stopped at 13:19 p.m., and caused a 43.2 × 104m3 landslide mass which slipped into the Luogudong River, the secondary branch of Yangtze River. Fortunately, the local government gave an efficient early warning and organized a successful emergency evacuation. Nobody was injured or killed in this landslide failure event. The Daling Hydropower Station and its attached buildings were eradicated by the landslide. Posterior to the failure, a newborn free surface occurred on the dip slope. The remaining body of the landslide poses a great threat to the safety of both the village and the Three Gorges Reservoir operation. Subsequently, an emergency monitoring system has been placed on the slope to observe any subsequent deformation. By applying the kinematic model, this article will give a general outlook on the failure event and investigate the geological features which caused the slope instability. Also, the two inclined blocks models are introduced in the back analysis and show a good comparison to the site observation results. This article will provide guidance and suggestion for the stability analysis of similar highly weathered bedded landslides in the China Three Gorges Reservoir area.