Author(s): Hajime Nakagawa; Takaharu Utsumi; Kenji Kawaike; Yasuyuki Baba; Hao Zhang; Ripendra Awal
Linked Author(s): Hajime Nakagawa, Kenji Kawaike, Yasuyuki Baba
Keywords: Embankment; Erosion rate; Overtopping; Suction; Unsaturated bed
Abstract: The river embankment has complicated soil condition. It may fail by erosion due to overtopping. The breached outflow discharge highly depends on rate of erosion of embankment. Therefore, it is important to study erosion rate of embankment of different sediments in different hydraulic conditions. This study is focused on erosion of unsaturated river embankment caused by overtopping. The experimental results of embankments prepared by non-cohesive fine sediments show that rate of erosion in small sized sediment is smaller compare with bigger sized sediment. However, the rate of erosion proposed by Takahashi et al. is inversely proportional to sediment size in the bed erosion velocity for unsaturated bed. Shear strength due to suction plays vital role in erosion of unsaturated fine sediments. Therefore, a new erosion equation is developed considering the resisting shear stress due to suction on unsaturated bed. The shear strength of an unsaturated bed is correlated with soil-water characteristic curve. The proposed model is tested for embankment of different sediment sizes. The numerical model considering suction in erosion rate is capable to predict erosion rate of non-cohesive fine sediments as observed in the experiments.
Year: 2010