Mechanism Study On River-bank Collapse Under The Condition Of The Water Level Sudden Change

China is a big river country,and there are more than 1,500 rivers with a drainage area of more than 1,000 square kilometers.Due to the long-term interaction between the water flow and the bank slope,under the influence of externa l factors such as rainfall,sudden changes in water level,and earthquakes,it is easy to trigger large river bank collapse disasters.According to incomplete statistics,since the founding of New China,in the mainstream of the 1900 km middle and lower reaches of the Yangtze River,the bank collapsed to a length of 1582 km,accounting for 41% of the total length of the shoreline.The width of the collapse of the shoreline each year is tens or even hundreds of meters,and the fertile farmland's average loss is more than 7,500 acres.The collapse of rivers will not only affect the flood protection of embankments,but also affect the operation of navigation channels and the structural safety of buildings along the river such as piers and bridges.At present,the issue of river bank collapse has developed into an important issue that restricts the safe operation of rivers and confuses water conservancy construction managers and coastal residents.The bank-breaking rivers are characterized by short-term nature,abruptness and drastic nature.The mechanism is relatively complex and involves many disciplines.There is no more unified viewpoint so far,so the research on the river bank collapse mechanism needs further improvement and improvement.In this paper,the riverbank collapse disaster is taken as the research object,and the collapse mechanism is analyzed by means of data collection,field investigation,generalized model test and theoretical analysis.The main work and achievements are as follows:1.Summarizing the research status,classification and characteristics of bank collapse;2.Constructing the stability calculation model of sloped bank slope under multi-factor cooperation.Deducing the calculation formula of bank slope stability coefficient under different working conditions,and ascertaining the influence law of each factor on bank slope stability;3.An in-house physical model experiment was conducted to reveal the instability pattern,failure criteria,and occurrence conditions of the bank slope under the sudden water level sudden change;4.Based on theoretical analysis and model tests,the river bank collapse mechanism under the condition of sudden water level sudden change was proposed.