EGU21-6884, updated on 04 Mar 2021
https://doi.org/10.5194/egusphere-egu21-6884
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Numerical study on the effect of edge scouring on stability of soft mattress in the Yangtze estuary

Aofei Ji1, Peng Hu2, Zhiguo He3, and Fengfeng Gu4
Aofei Ji et al.
  • 1Zhejiang University, Ocean college, Port, Coastal &Offshore Engineering, Zhoushan, China (21834100@zju.edu.cn)
  • 2Zhejiang University, Ocean college, Port, Coastal &Offshore Engineering, Zhoushan, China (pengphu@zju.edu.cn)
  • 3Zhejiang University, Ocean college, Port, Coastal &Offshore Engineering, Zhoushan, China (hezhiguo@zju.edu.cn)
  • 4Shanghai Estuarine and Coastal Scientific Research Center, Shanghai, China (6737632@qq.com)

Abstract: In the Yangtze River Estuary deep-water channel regulation project, soft mattresses have been widely used to reduce bed erosion and thus improve stability of bridges/piers/levees/dikes. However, soft mattresses are also subject to failure due to the continuous and gradual scour in their edges, which have been a major risk for their stability. Here we report a preliminary numerical study on this issue. Firstly, a depth-averaged two-dimensional hydro-sediment-morphodynamic model is applied to simulate edge scour process for the submerged dike of the Jiangyanansha in the Yangtze estuary. For this purpose, physically-based sediment erosion parameterization is proposed to take account of the effect of the soft mattresses. Compared with the inner area of the soft mattress, only the edge area has stronger erodibility. Numerical comparative studies indicate that a scouring pit may develop to the vicinity of the submerged dike without the protection of the soft mattress, whereas under the protection of the soft mattress, the scouring pit can be largely controlled. Nevertheless, as the scouring process continues, the pit region and depth increase, which may finally lead to failure of the soft mattress. Finally, full 3D high-resolution simulations of the near-bed flow structure with/without edge scour are conducted using flow3D to shed light on the failure mechanisms of the soft mattresses.

Keywords: submerged dikes, soft mattress, erodibility, Yangtze estuary, edge scour, flow structure

How to cite: Ji, A., Hu, P., He, Z., and Gu, F.: Numerical study on the effect of edge scouring on stability of soft mattress in the Yangtze estuary, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6884, https://doi.org/10.5194/egusphere-egu21-6884, 2021.

Corresponding presentation materials formerly uploaded have been withdrawn.