Three-dimensional Numerical Simulation Of Landslide Surge And Analysis Of Its Propagation Characteristics

Slopes of reservoir and river course are infiltrated by water for a long time,which easily causes slope instability and landslide.The landslide impinges on the water at a certain speed,and the water is affected by the impact and extrusion of the landslide,which often sets off huge surge waves.The surge waves will be spread along the reservoir and the river,posing a great threat to the life safety of the wading buildings and residents along the way.Therefore,the generation and propagation characteristics of landslide surges are researched to provide scientific basis for engineering disaster prevention and mitigation.Landslide surge wave is taken as the research object,and a numerical model of landslide surge wave based on CFD software Flow-3D is established in this page.It's accuracy and effectiveness are verified.The orthogonal test method is adopted to comprehensively analyze several factors that affect the primary wave height of landslide surge wave.In this paper,the characteristics of water wave in the near field and its propagation in the three-dimensional space are studied.The main research results are as follows:(1)The primary and secondary relationship among the influencing factors of landslide surge is revealed.The range analysis was carried out by using the orthogonal test method to research the seven influences of the landslide length,width,thickness,the leading angle of the landslide,the inclination angle of the slope plane,the water depth and the entry velocity of the landslide.Among them,the thickness,width and velocity of landslide are the three main influencing factors of landslide surge wave.(2)The near-field wave characteristics of landslide surges are analyzed according to the numerical simulation results,and the types of the waveforms in the near-field region are determined;The semi-empirical formula for the maximum amplitude of the near field surge wave and the energy ratio of the near field primary wave to the total potential energy can reach to 51%,which reveals the characteristics of the primary wave height of landslide surge wave.(3)The wave propagation characteristics and attenuation law are analyzed.In the process of propagation,the attenuation of wave peak and trough was symmetric with respect to the sliding direction of the landslide.When the angle between the wave propagation direction and the landslide movement direction is less than 75°,the amplitudes of the initial surge wave peaks and troughs will be decreased with the increase of the propagation distance,and the rate of attenuation of the trough amplitude is greater than that of the peak.In the near field,the propagation velocity of the initial surge wave is less than that of the isolated wave,and the peak propagation velocity of the initial surge wave is close to that of the isolated wave when x/h=3.(x represents the horizontal distance between this point and the entry point of the slider,unit is m;h denotes water depth in m)The first wave period of landslide surge is obtained by statistical analysis and multivariate nonlinear regression analysis.According to the numerical simulation results,the wave steepness and Ursell number of the surge wave are calculated,and it is judged that the surge wave is nonlinear and belongs to medium depth wave.The energy conversion rate between the kinetic energy of the landslide and the surge wave is estimated.(4)From the perspective of the primary wave height of the surge wave and the attenuation rate of the surge wave propagation along the path,the similarities and differences of the surge wave generated by the impact of the landslide in the two-dimensional model and the threedimensional model are compared and analyzed,and the main reasons for the difference in the characteristics of the surge wave are discussed.