Study On The Accumulation Characteristics Of Landslide In Mountainous River And Its Influence On The Waterway

When the landslide slides into the channel,it changes the shape of the riverbed directly.It causes the channel scale to be insufficient or even clogging the channel,which blocks flood and deteriorates the channel navigation.Therefore,the accumulation patterns in different types of watercourses should be studied.The results can be used to predict the influence of the river topography and navigation conditions.This provides the accurate underwater accumulation characteristics for the later waterway regulation.This paper applies theoretical analysis and numerical simulation to study the accumulation of landslide in river channel.The paper mainly studies the influence of the volume and the channel type on the accumulation form and the structure characteristics,and also discusses the influence of the form of the avalanche body on the channel scale and the flow state.The main conclusions are as follows:(1)According to the topographic features and hydrological data of the river,the river section of the research area is generalized into v-type straight river section,v-shaped bend river section,u-type straight river section and u-bend river model.According to the analysis,the factors that affect the landslide accumulation are the center of gravity,volume,slope,material composition and friction coefficient.(2)The movement time of collapse body in v-type channel is less than that of u channel.For the u-shaped and v-shaped channels,the movement time of the collapse body is affected by the slope of the river bank and the width of the bed.When the slope of the river bank is smaller than 50°,the movement time is greatly influenced by the slope;When the slope is greater than 50 °,movement time is less affected by the slope,and greatly influenced by terrain.This conclusion can be used to predict the movement time of landslide when the slope and width of river bed are fixed.(3)The accumulation length of the landslide body on the bank of different slope increases with the increase of slope and then decreases.When the slope is increased from 20 ° to 35 °,rapidly increasing pile length.When the slope is more than 35 °leveled off with the increase of the pile length.After the slope up to 50 ° pile length present small amplitude decreases with the increase of slope.The reason is that when the slope is small,the slope has less constraint on the landslide.The initial acceleration of the landslide is larger with the increase of slope,so it can move longer.However,when the slope increases to a certain value,the constraint of the slope becomes larger.However,the width of the riverbed is limited.This causes the collapse body to move less on the riverbed.The stack length is small.This can be used to predict the extent of the landslide in the river when the slope of the river is known.(4)When the volume of different collapse body slide pile up in the same river,pile length,pile width,stack height increases as collapse,body size,but when the volume is more than 80000 cubic meters of pile length,width and height of slow increase trend.This is mainly due to the increase of local velocity in the upper part of the accumulation body,which washes away most of the rock.This can be used to determine the trend of the collapse of different scales in the channel,and predict its influence on navigation.(5)When the landslide volume is below the million level,the accumulation parameter has no obvious influence on the channel scale of the study area,but it has a great influence on the flow field of the channel.The maximum flow velocity of the pile top is 6.7m/s.Upstream backwater range is 200 m ~ 600 m.The maximum transverse velocity of the curved section can reach 0.7m/s.The reduction rate of local horizontal water level can reach up to 8%.The vertical water level decline rate can be up to1.3%.This poses a great threat to the safety of the ship.