Comparison of Simulated Bank Erosion Processes in the Upper Jingjiang Reach Using the Circular and Planar Sliding Modes

A general bank erosion model at section-scale was proposed, based on the bank erosion modes of circular and planar sliding.The model adopts the most dangerous sliding surface method, and combines with the calculation modules of bank-toe erosion, change of underground water level and bank stability analysis, which can consider the bank-toe accumulation of failed bank soil in stability analysis and the vertical stratification structure of the bank soil for the mode of circular sliding. Using the proposed model based on the planar and circular sliding modes, the bank erosion processes at two typical sections of the upper Jingjiang Reach (Jing55 and Jing61) in 2014 were calculated.The results indicate that:(i) the simulated collapse numbers at Jing55 based on the circular and planar sliding modes were 10 times and 2 times, with the errors of 21.5% and 29.9%, respectively.The simulated collapse numbers at Jing61 were 7 times and 1 time according to these sliding modes, respectively, with the errors of 1.0% and 6.1% respectively.In general, the bank erosion modelling based on the circular sliding mode is more suitable for the sections with gentle slopes;and (ii) the sensitivity tests of relevant riverbank soil parameters were carried out.The influence of the vertical soil stratification structure on bank erosion was analyzed.With an increase in cohesion and internal friction angle, the simulated bank erosion width gradually decreased, and the variation trend of frequency and width of bank erosion was related to the physical soil properties.In addition, as a weak interlayer, the presence of sand layer can increase the total width of bank erosion by increasing the width of single collapse or the number of collapses.