Potential risk analysis on a Jianchuandong dangerous rockmass-generated impulse wave in the Three Gorges Reservoir, China

Abstract

An impulse wave generated by landslide is a major detriment to waterway safety in reservoirs. Thick-bedded pillar-shaped rockmass is one of the principal potential tsunami generators in the Three Gorges Reservoir and other reservoirs around the world. However, the impulse wave generated by a pillar-shaped rockmass was seldom studied in the past. The Jianchuandong dangerous rockmass lies on the left bank of Yangtze River in the Wu Gorge of the Three Gorges Reservoir with a total volume of 36 × 104 m3 or so, standing as a serious threat to the safety of the waterway, a renowned “expressway”. Along with the deterioration of the base mass, the Jianchuandong rockmass is likely to either slide or topple due to instability. A solid–fluid coupled computational fluid dynamic model is built to calculate the potential impulse wave induced by the Jianchuandong dangerous rockmass. The potential impulse waves under four working conditions with two failure modes and two water levels are discussed. Numerical simulation results show that the potential maximum wave height and maximum run-up are 47.1 and 27.2 m, respectively. Based on the integrated calculation results, we deduce a 15 km channel segment likely to be affected by the Jianchuandong rockmass-induced impulse wave for early warning purpose. By engineering geological analogy, the calculation results are verified with the instance data of two impulse wave events generated by landslides in the Three Gorges Reservoir. The purpose of this study is to provide a technical support for early warning, prevention and control of hazards associated with the Jianchuandong dangerous rockmass and to serve as a reference for researches on impulse wave generated by pillar-shaped rockmass collapse around the world.