Experimental Study On The Influence Factors Of Debris Flow On The Bottom Erosion Of Channel

“5.12” Wenchuan earthquake hit a variety of secondary earthquake disaster,especially in the most serious impact of debris flow.During the earthquake and after the earthquake,a large number of landslides and collapses will form a large number of loose accumulation in the channel,which also provides a rich material condition for the continuous expansion of the debris flow after the outbreak.Based on the data inspection and field investigation,this paper studies the influencing factors of the erosion effect of the debris flow on the bottom of the channel by using the indoor sink simulation experiment.Through a large number of physical experiments,the relationship between the erosion effect of the debris flow on the bottom of the channel and the initial mud slurry concentration,channel slope and initial moisture content is obtained.The main research results are as follows:(a)When the mud flows through the channel filled with loose sand,it can form a faucet with a large number of particles and a sharp steep front at the front,and the speed of the faucet is much smaller than the subsequent fluid flow rate.This phenomenon changes with slope and mud concentration.When the slope is large,the mud flushing effect is obvious,the fluid front summit has obvious uplift faucet,and the content of solid particles in the faucet is higher;when the slope is small,or the mud concentration is large,the mud front peak will not form the leading,And the front peak is almost free of solid particles.(b)During the experiment,when the mud flows into the sink,the kinetic energy of the slurry is large,and it is rapidly eroded in the loose bulk of the upper part of the experimental tank.The solid particles taken by the mud flushing are mixed into the slurry and continue to move downwards,The process of performance for the next cut erosion.The overall pattern of performance for the gradual erosion intensified,the formation of the debris flow weight increasing.(c)Slurry concentration,groove gradient can affect the debris flow infiltration capacity and erosion rate.Considering the effect of slurry concentration,with the increase of slurry concentration,the infiltration capacity of debris flow in the channel loose deposit decreases,the erosion rate decreases and the erosion amount decreases.When only the influence of slope is taken into account,Slope not only affects the critical flow of debris flow initiation,but also significantly affects the erosion of the debris flow on the bottom of the ditch bed.The greater the slope,the greater the erosion rate of the slurry to the bulk accumulation body,and the larger the later scale of the debris flow.(d)In addition to the slurry concentration and the wedge slope,the initial moisture content of the loose bulk of the channel will significantly affect the flowability and infiltration capacity of the debris flow through the channel,thus affecting the erosion rate of the debris flow.The dry sand is more easily adsorbed by the slurry and migrates with the mud relative to the loose deposits with higher moisture content.The fine solid particles in the slurry will enter the native skeleton of the bulk deposit and combine with them to form a relatively stable and relatively stable deposit,which will reduce the erosion ability of the mud.