Modeling of the Composite Bank Failure Process Using BSTEM

Considering the near-bank fluvial erosion,the soil composition and mechanical properties,the degrees of riverbank stability for composite bank in the Upper Jingjiang Reach(UJR) were analyzed during different water level periods using BSTEM,and the process of bank failure was simulated.The results indicated that the degrees of riverbank stability are high during the periods of low water level and water-level rising before the flood season,which leads to the stage of weak bank failure,and they are low during the periods of high water level and water-level recession with the continuous bank collapse occurring,which belongs to the stage of intensive bank failure.In addition,the effects of bank toe erosion and water table variation on the degree of bank stability were investigated.This analysis indicated that these two factors have an important influence on the process of bank failure,and they can cause respectively intensive bank failure during the high water and recession periods.Finally,with the bank toe erosion,water table variation and deposition form of the collapsed bank soil being considered in the calculation,the process of bank failure of the right riverbank at Jing34 section was simulated over the period from Nov.2008 to Oct.2010.The model-predicted results were in well agreement with the measured data of the total bank retreat width and the collapsed bank shape.Therefore,these influencing factors should be included when simulating the process of composite riverbank failure.