抄録
An overhanging failure is one of major problems in river engineering affecting the riverbank geometry. Unfortunately, the previous studies had limitation on the coupling fluvial erosion and overhanging failure. Therefore, the aim of this paper is to introduce new coupled processes for simulating the fluvial erosion and overhanging failure of the experimental banks as well as the real riverbanks at U-Tapao River in Thailand.
For fluvial erosion, the actual shear stresses of the experimental banks are between 0.68 and 1.23 Pa, while at the U-Tapao River, they are within the range of 18.51 to 22.52 Pa. Moreover, the critical shear stresses estimated by the percentage of silt-clay content of the experimental banks are within the range of 0.38 to 0.57 Pa, while at the U-Tapao River, they are between 9.44 and 12.99 Pa. Additionally, the previous relationship between the critical shear stress and the erodibility coefficient indicate that they do not follow the present values of the experimental results and the U-Tapao River. Furthermore, the critical shear stress and the erodibility coefficient showed that these parameters varied significantly from one site to another site. Therefore, relationship between the critical shear stress and the erodibility coefficient are needed to be measured locally. For overhanging block stability, the results revealed that the dominant overhanging failure of the experimental study is the beam-type failure while the shear-type failure is the dominant failure mechanism in the U-Tapao River.
Finally, the overhanging failure was simulated by the present numerical model within the frameworks of the fluvial erosion and overhanging failure. The numerical results were validated with the temporal variations of spatially averaged bank width. Moreover, this validation results showed a good agreement between the numerical results and the experimental results.
