Wavelet Analysis On Propagation Of Landslide Surge In V-shaped River

Landslide surge disasters are very common in mountainous rivers in China,which will threaten the lives and property safety of coastal residents.The two banks of mountain rivers are generally V-shaped.Most of the surges generated by landslides occur in the form of low-frequency waves,and there are some potential hazards to water conservancy facilities and both banks of the river.Therefore,it is necessary to study the propagation characteristics of landslides surges in V-shaped river.It can provide important significance for disaster prevention.Based on FLOW-3D software,a three-dimensional V-shaped River landslide numerical model is established,which considers the propagation characteristics of surge from five important physical parameters,i.e.the water inflow velocity of sliding block,the water depth of river channel,the angle of landslide,the angle of climbing slope and the volume of sliding block.Firstly,the numerical model is validated.The results show that the free wave surface is in good agreement with the wavelet energy spectrum,and the main control frequency and waveform of the surge are similar.By comparing and analyzing the propagation process of surge in broad river and V-shaped river,the main difference is the amplitude change of the first wave of surge and the transfer of the dominant frequency along the process.Then the surge propagation process under 27 different physical conditions in V-shaped River is analyzed.It is found that the main control frequency shifts from lower to higher frequencies.The variation of main control frequency of surge is mainly affected by river depth,ramp inclination angle and runup slope angle.By comparing with the group velocity of linear theory,it is found that the propagation velocity of impact wave is slightly higher than that of linear theory and the variation trend is consistent.It can be used to approximate describe the propagation velocity of landslide surge in V-shaped River.Finally,the reflection coefficients of the main control frequencies of landslide surge in V-shaped River is estimated.The results show that the reflection coefficient of landslide surge in V-shaped River increases with the distance from the reflection bank.