Physical Model Experiments of Landslide-Induced Surge in Three Gorges Reservoir

The impoundments of Three Gorge Reservoir have obviously intensified the reservoir bank landslide deformation since 2003. Landslide deformation can cause not only damages, but also evokes great surge once high-speed landslide sliding into reservoir, which is a potential hazard far worse than landslide itself. Owing to the reservoir impoundment, Qianjiangping landslide in Three Gorges Reservoir Area (TGRA) occurred on July 13, 2003. The highest height of landslide-induced surge reached 39 meters which resulted in wave spreading more than 30 kilometers far away along the channel, causing casualties and property losses. In order to study the characteristics and propagation law of landslide-induced surge, based on the major scientific project in TGRA, this paper presenta comprehensive researches on landslide surge hazard in TGRA through large laboratory physical model experiments. Through the statistical analysis of geological data about the potential landslides in TGRA, adopting the orthogonal experimental design method, we formulated the experiment scheme which included landslide scale, speed entering into the water, sliding plane obliquity, water depth, and slope angle. Besides, we took the channel of Baishuihe landslide in TGRA as prototype, established the river physical model in map scale 1∶200, and thus developed landslide surge three-dimensional physical model experiment by adopting the experimental control system and measurement system. According to the careful physical model experiments, we obtained reliable experimental data of landslide surge. Based on the morphological changes of landslide surge, we confirmed the concept of head wave. Then based on the classical landslide surge formulas proposed by Noda and Pan Jiazheng, by analyzing the measured data, we deduced the landslide surge calculation formulas in TGRA. At last, taking Baishuihe landslide being in deformation as an example, these formulas were used to forecast the maximum head wave height and the decay law of landslide surge along the channel.