Experimental Study On Dynamic Response Of Submarine Slope Under Internal Solitary Waves

Internal wave is a kind of undulation phenomenon that occurs in the seawater ubiquitously in the ocean.It is formed when stratified seawater is disturbed,and can cause up and down of equal density surface up to hundreds of meters.Internal solitary waves are an important part of the deep ocean dynamic process of the South China Sea,and are the main dynamic factors that cause the resuspension and migration of seabed sediments.The study of internal solitary waves suspending seabed sediments and the ability to modify the bottom quality is of great significance for tracing the sedimentary history of the South China Sea,predicting the evolution pattern of the South China Sea bottom quality,and analyzing the trigger mechanism of geological disasters.In this paper,an internal solitary wave tank is built in the School of Environmental Engineering,Ocean University of China.Fresh water and salt water are used to make stratified fluids.Gravity collapse is used to create internal solitary waves.The density difference between the upper and lower fluids is adjusted to create different amplitudes.(12cm,14 cm,15cm)internal solitary waves.And set up a sediment slope at the bottom of the tank,and use the layered paving method to pave the slope.A total of 3 groups(3°,6°,9°)slope slope conditions are set.And the dynamic response law of the slope is monitored by the earth pressure sensor and pore pressure sensor set at 1cm in the slope.A flow meter is set up at the fluid interface in the upper and middle of the slope to monitor the change of the flow velocity on the slope,and 3 layers(layer 10,layer 19,and layer 29)are selected for analysis.The movement process of internal solitary waves was recorded and observed by a highfrequency camera.Studies have shown that the accumulation of excess pore water pressure occurs when the internal solitary wave maintains a complete waveform and passes over the sediment.The change of slope angle will cause the accumulation of excess pore water pressure to change at the foot of the slope.The dynamic response of gentle slope sediments is more sensitive to the change of internal solitary wave amplitude,and the time of slope dynamic response is also prolonged with the increase of internal solitary wave amplitude.The change of the excess pore water pressure during the wave motion is not unidirectional,but the accumulation and release process exist at the same time,and the suppression effect of the slope on the internal solitary wave is not unidirectional either.There is a big difference between the dynamic response of the top and the middle of the top of the slope.The water flow formed by the breaking of the internal solitary wave will be affected by gravity after it rushes out of the top of the slope along the slope,and will curl and form a vortex behind the top of the slope,making the slope The sediments behind the roof are subject to greater dynamics.The strength of the turbulent water flow generated by the breaking of the internal solitary wave determines the speed direction of the vortex formed at the middle position of the slope top,and then affects the force on the middle part of the slope top.This paper summarizes the dynamic response laws of slopes with different slopes under the action of internal solitary waves,analyzes the interaction relationship between internal solitary waves and slopes,and studies the dynamics of slope sediment instability and failure under the action of internal solitary waves and slope stability Analysis will play a guiding role.