| The landslide generated waves in a reservoir and its run-up over the dam are highly complex physical processes involving fluid-structure coupling,wave generation,refraction,diffraction,reflection,nonlinear deformation,and slope run-up breakage.Accurately predicting these processes is crucial for ensuring dam safety and preventing disasters.Previous studies have shown that the inflow of landslide water can induce four types of waves: nonlinear oscillatory waves,nonlinear transition waves,solitary-like wave and transient bore.These waves exhibit distinct characteristics,including their generation mode,propagation characteristics,and run-up process.This variation highlights the different generation regimes within the landslide surge process.However,the complex fluid-structure interaction during the landslide surge poses a significant scientific challenge in understanding the specific types,processes,and regimes involved.Although this issue has received attention,it remains unsolved,resulting in a research gap in the understanding of the run-up process.Therefore,the formation process of different types of waves and the interaction between fluid and structure are thoroughly investigated.Mechanical experiments are conducted to analyze the mechanical characteristics of the landslide generated waves,and the correlation between wave height and run-up is studied.A formula based on the findings of the mechanical research is derived to describe the first wave and run-up.Additionally,focusing on the instability of H1 and 1# landslides in the Yangqu Hydropower Station,numerical techniques are explored to enhance the computational efficiency of the 3D model through grid optimization.This allows for accurate and efficient prediction of the generation,propagation,and run-up process of the landslide surge in the Yangqu Hydropower Station.The specific research contents and achievements of this paper are as follows:(1)Study on the for generation regime of landslide induced waveNumerical and theoretical investigations have been conducted to study the generation of water waves caused by a rigid landslide.Based on the motion characteristics of landslides,three distinct types of landslide motions have been identified: piston-like,plunger-like,and transition landslide motions.The analyses conducted in this study reveal that piston-like landslides generate solitary-like waves and dissipative transient bores.Plunger-like landslides,on the other hand,generate nonlinear oscillatory waves,while transition landslides give rise to transition waves.(2)Study on the for generation regime of landslide induced waveBased on a combination of physical experiments,numerical simulations,and theoretical analysis,a dynamic model for rigid landslide,as well as prediction models for nonlinear oscillatory waves,nonlinear transition waves,solitary-like wave and transient bore,have been developed.The research findings indicate that the rigid landslide dynamic model can effectively simulate the entire process of landslide movement with high accuracy.To address the issue of inaccurate and unstable fluid-structure coupling in 3D simulation software,the model was integrated with the Flow3 d.Validation of the prediction models against experimental data demonstrates a strong correspondence between the predicted values and the actual measurements for dissipative transient bore and solitary-like wave.Furthermore,the first-order approximation models for nonlinear oscillatory waves and transition waves show excellent accuracy.(3)Study on theoretical model of wave run-upThe uphill process of surge waves is assumed to follow the nonlinear shallow water equation.A theoretical model is developed to calculate the uphill height of nonlinear oscillatory waves,nonlinear transition waves,and solitary-like waves on the slope.The model is further solved analytically.The results show that the analytical solution aligns well with the values obtained from 3D simulations.Whether it is the first wave or the secondary wave,both methods effectively simulate the run-up process of nonlinear oscillatory waves,nonlinear transition waves,and solitary-like waves on the slope.By examining the correlation between the Iriarren number and the relative wave peak height,the breaking types of nonlinear oscillatory waves,nonlinear transition waves,and solitary-like wave can be distinguished.However,the breaking of transient bores cannot be distinguished using this approach.(4)Study on in-situ landslide generated wave of Yangqu Hydropower StationThe application of the research mechanism reveals that reservoir landslide generated waves predominantly consist of weak nonlinear oscillation waves.The wave height prediction model exhibits a calculation error of less than 10% in the near field,but the error rate increases to 30% for three-dimensional problems in the far field.The run-up theory model demonstrates a prediction error of less than 5% on uniform bank slopes.However,in complex river channels,the influence of terrain significantly affects wave diffraction,refraction,and aggregation.As a result,the analytical solution tends to underestimate the overall wave value,leading to low prediction accuracy of the model.Furthermore,a 3D prototype-scale landslide-generated wave model is developed for the reservoir area,specifically designed to accurately calculate wave problems in complex river channels.This model achieves a wave height and run-up accuracy of95% for both the first and secondary waves.However,the subsequent wave superposition introduces randomness,which diminishes the prediction accuracy.In addition,physical models of H1 and 1# landslides at a scale of 1:200 in Yangqu Hydropower Station,China,were established.The study investigates the wave heights generated by landslides of different sizes,such as 1 million m3,2 million m3,and 5 million m3.The analysis assesses the impact of surges on the stability of bridges and dams,identifying key factors that significantly influence landslide surges.The sensitivity of wave characteristics,slope run-up characteristics,and dam overtopping processes to factors such as landslide sliding speed,landslide shape,water depth,and landslide properties is examined.The findings reveal that wave height,climb height,and overtopping water volume increase with sliding speed,but the growth rate diminishes or stabilizes when the sliding speed exceeds 30 m/s.The sensitivity of other factors affecting waves is lower compared to sliding speed. |
