Characteristics of the landslide dams induced by the 2008 Wenchuan earthquake and dynamic behavior analysis using large-scale shaking table tests

The Ms 8.0 Wenchuan earthquake triggered at least 257 landslide dams. More than 300 aftershocks with the magnitudes higher than Ms 4.0 occurred after the formation of these landslide dams, which might largely influence the structure and soil properties of these dams. This paper aims to comprehensively investigate the characteristics of the landslide dams induced by the 2008 Wenchuan earthquake, and study the dynamic behaviors of the landslide dams under aftershocks using large-scale shake table tests. First, the characteristics of the landslide dams, including the distribution, geometric parameters, stability and longevity, mitigation measures and the influence of the aftershocks are proposed. Then, two groups of shaking table tests to simulate the dynamic behaviors of two types of landslide dams under aftershocks are illustrated: one with quartz sand contained 10% kaolin (Dam I) and the other with quartz sands all (Dam II). Finally, the results of the tests, including the acceleration distribution, dam deformation and dam breaching process, are discussed. Through this study, it is found that the landslide dams caused by high-magnitude earthquakes have distinctive characteristics, which may largely influence the stability, breach process and risks of these dams. In the model tests, the accelerations are generally higher on the surface of the dams, either on the crest or on the both upstream and downstream slopes. The Dam I was prone to settlement and cracking. The aftershocks may not directly trigger the failures of landslide dams, but accelerate the overtopping failures by lowering the dam crest with settlement and cracking.