Numerical Simulation Of Landslides And Landslide-induced Waves On Bank Slope

Recently a number of large hydropower engineerings with high dam and vast reservoir have been put into operation. In the near future, there will be some large hydropower engineerings successively completed in southwest China as well. Most of these engineerings have high rock slopes, where fracture rock masses are often observed, and are located in poor geological settings. Thesegreatly challenge the safety of the structures. Besides, local failure of the slope under the load of changing water level is likely to result in landslides, the higher of which would impose overload to the dam, and even pass over the dam. All of these put a great threat to the reservoir and downstreams.An analysis system of stability of bank slope and process of landslide-induced waves is proposed in order to acquire forecast and warning information of the stability safety of the slope and the risk of landslide-induced waves. We firstly perform the stability analysis of bank slope and predict the potential landslide, based on which we could perform the simulation of landslide-induced waves.The stability analysis of bank slope adopts three-dimensional nonlinear finite element method based on the Deformation Reinforcement Theory. Some simplified models often encountered in engineering practice, including homogeneous rock slope, rock slope with weak intercalated layer and reinforcement for toe area, indicate the significant role of unbalanced forces in the stability analysis of rock slope that it can be used to determine the potential landslides.The risk analysis of landslide-induced waves utilizes the tsunami simulation code COMCOT based on shallow water equation and fluid-like granular flow model, which can simulate the triggering and propagation process of landslide- induced waves, while the input of potential landslides adopts the results discussed above. When using fluid-like granular flow to simulate the landslides, the basal friction has an obvious effect on the movement of landslides. Through sensitivity analysis of the parameter, it is shown that smaller basal friction coefficient would result in faster velocity of landslides, and higher amplitude of the first wave.Using the above analysis system, we can finish the analysis of the stability of rock slope and the risk of landslide-induced waves of Guobu slope of Laxiwa Hydropower Station. The stability of the slope is analyzed on 2452 m normal water level and 2448 mwater level under normal condition and the treat effect of slope cutting is verified.Meanwhile, three potential landslides are determined based on the stability analysis of slope, and then the numerical simulation of landslide-induced waves is performed. The result shows that the highest waves propagated before the dam is 6.8m, and that some part of nearby slope may suffer high run-up, which would affect the safety of this engineering to some extent.The analysis system of stability of bank slope and process of landslide-induced waves proposed by this thesis can be well applied in the risk analysis of landslide on bank slope. The results could provide effective suggestion of risk elimination andreinforcement for dangerous bank slope and other similar engineerings, and provide precautionary information of the risk of landslides and surges for departments related.