Research On The Influence Of The Cross-section Characteristics Of The Reservoir Area On The Propagation Of Landslide Surge And The Response Of Gravity Dams

In recent years,China's hydropower industry has been prospering,and a large number of DAMS have been built.Most of the construction projects are deeply affected by the complex geological structures and seismic zones of mountain valleys,and more and more attention has been paid to the slope instability and the threat of landslide surge waves in reservoir areas.Therefore,the study of the formation and propagation of landslide surges is of great practical significance to the safety prevention and engineering construction of DAMS and reservoir areas.There are many factors affecting landslide surge,so the research is not enough at present.Firstly,the accuracy of the two dimensional and three dimensional numerical models is verified by two physical model tests of landslide surge wave.The calculated results are in good agreement with the experimental results.Fluent software was used to establish a two-dimensional numerical calculation model of landslide surge wave for V-shaped and U-shaped sections.By changing the sliding speed of the slider and the ratio of width to depth of the water surface,the wave height and climb characteristics of the surge wave were analyzed.Different bottom slope of the same water depth is set up and the same bottom slope landslide under different water depth is surge calculation model,set up the right end wave zone,to the landslide surge wave wave change situation,the first and second wave attenuation law of the most high waves in the time space,surge flow velocity and the surge propagation speed,the dynamic water pressure surge force field are studied,such as analysis of cross section area with different characteristics are summarized case law of landslide surge propagation form and spread.The results show that under the same hydraulic conditions,the characteristics of landslide surge wave propagation in V-shaped section are more obvious,and the surge wave in narrow and deep V-shaped section is more harmful.The bottom slope of reservoir area will reduce the wave height and wave surface velocity during wave propagation,and the larger the bottom slope is,the greater the influence is.On the same bottom slope,with the increase of water depth,the first wave height decreases,the second wave height increases,and the wave propagation velocity increases gradually.If the landslide occurs near the dam,the surges associated with the landslide will inevitably impact the retaining dam.In view of the impact of landslide surges on the dam surface in the reservoir area,the characteristics of landslide surges in V-trapezoidal section,U-shaped section and V-shaped decreasing section and the response of gravity dam are studied by using the method of two-way fluid-structure coupling combined with Workbench software.The three-dimensional wave height variation,wave velocity distribution and water level fluctuation in front of the dam during the formation and propagation of landslide surges are analyzed.The propagation patterns of the first wave and the second wave of landslide surges in reservoir areas with different sections are analyzed,and the propagation characteristics of the wave body along the coast are pointed out.The displacement and stress response of the dam body are contrastively analyzed,and the displacement and stress vibration law of the dam body is summarized.The results show that the wave height and wave surface velocity of the first and second waves in the V-trapezoidal section are higher than those in the U-shaped section,and the wave body along the U-shaped section is higher,while the surge wave in the V-shaped decreasing section reaches the dam later,but the value of water level mound is larger.The difference of section shape in the reservoir area will affect the displacement and stress distribution law of gravity dam to some extent,and the stress distribution of the dam body has great difference under different working conditions.The response of gravity dam with U-shaped section is the most unfavorable,and the vibration displacement and stress of the dam with V-shaped decreasing section are the least.