Experiment and simulation studies on lateral scouring migration behavior of meandering channel
|Keywords:||河道沖刷偏移;渠槽實驗;岸壁穩定;三維動床模式;張力裂縫;Channel scouring migration;experiment;riverbank stability;3D mobile-bed model;tension crack|
This study investigated the lateral scouring migration behavior of meandering channels through laboratory experiment and numerical modeling. In the experiment, two common types of failure on cohesive banks were considered, which include pla-nar failure and cantilever failure. The bank stability tests were carried out through river stage drawdown process and bank erosion respectively. In the numerical simu-lation, based on the limit equilibrium theory, a riverbank stability model was devel-oped by considering all the forces acting on the failure surface, along with the pres-ence of tension crack. The Boussinesq equation was used in the numerical model to calculate the time-varying groundwater level in the river bank in response to river stage drawdown. The interactions of the river water level and the groundwater level were examined to investigate their influences on the river bank stability. In addition, this study improved a 3D mobile bed model (RESED3D)(Chung 2012) by using near-bed velocity to replace depth-averaged velocity for better determination of the moving angle of bed-load materials. The test results collected in the laboratory experiments (including bed elevation variation in curved channels, planar failure and cantilevered failure) were used to verify the validity of numerical lateral scouring migration model. In addition, based on experiment test results this study modified the empirical formulas for determining tension crack location and bank failure angle in river bank stability analysis. The modified formulas were used in the numerical simulation model and their validity was confirmed with independent field observations.
|Appears in Collections:||Thesis|