In this paper two numerical models are analyzed and then, the advantages of each model are combined in order to simulate bank erosion in a river bend. The coupled model includes the effect of slump blocks produced by cantilever failure in cohesive banks and a corrected velocity profile that takes into account the lateral inclination of velocity profile at a bend. The model is developed for simulating flow in an infinitely long circular channel and is applied to seven cases. Four cases are tested for cohesive banks and three cases in non-cohesive materials. The capacity of the model to simulate the effects of slump blocks in cohesive banks is qualitatively analyzed and, for the case of non-cohesive banks, the numerical model is validated using experimental data obtained from the literature.
Linear stability analysis of fluvial sand bars with bank erosion is performed with the use of shallow water equations in two-dimensional flow, Exner equation and a process-based bank erosion model. An initially straight channel with erodible bed and constant width is assumed. The bank is also assumed to be erodible and composed of fine-grained sediment. The conditions allowed for alternate sand bars to grow are investigated considering the variation of aspect ratio, the magnitude of the transverse bank slopes, and the case of a channel with non-erodible banks. It is found that there exists a stable region in the range of small aspect ratios and small wavenumbers for the case of bar instability with bank erosion. The results also suggest that aside from the aspect ratio, the bank slope is one of the parameters that influence bed instability for the case of channels with erodible banks. This reveals that bank erosion has a stabilizing effect on the formation of alternate bars by increasing sediment supply, leading to an increase in bar wavelength.
Development of E-Simulator, which aims at reproducing the damage/collapse mechanism of soil, bridge and building structures against strong earthquakes, is a project of E-Defense. Data measured in E-Defense shake table tests are used for validation of E-Simulator. As a research subject in the field of soil structures, we aim to simulate the large-scale experiment of soil and underground structures conducted at E-Defense in February 2012. In this study, we conduct elastic analysis by using detailed solid model of soil and underground structures. Our main objectives of this research are to determine the suitable mesh of analysis model and to identify appropriate technique to impose lateral boundary condition. Then, we clarify how the detailed solid model can simulate the experimental result and the limitation of the elastic analysis and identify the issues to be taken care of in the elasto-plastic analysis.