Case study on analyse slope riverbank failure

• Main Author: Md Hadri Abdul Manan
• Format: Academic Exercise
• Language: English; English
• Published: 2022
• Subjects: GB1201-1598 Rivers. Stream measurements
• Online Access: https://eprints.ums.edu.my/id/eprint/35172/2/24%20PAGES.pdf; https://eprints.ums.edu.my/id/eprint/35172/1/FULLTEXT.pdf; https://eprints.ums.edu.my/id/eprint/35172/

Slope riverbank failure is a natural event globally in each riverbank, and a drawdown event usually causes slope riverbank failure. This case study aimed to analyze slope riverbank failures by evaluating the seepage and slope stability of the riverbank under slow and rapid drawdown. The riverbank in this case study is located at KM 3.49 Jalan Pantai Luagan in the Sipitang district (N 4° 59' 12.9" E 115° 31' 13.3"). A literature review was conducted to view the current study pattern, then retrieved a methodology based on the current study pattern. The methodology proposed in this study is by analyse the slope riverbank failure under slow and rapid drawdown occurrence using GeoStudio. A data collection was used as input to the software, based on the Boreholes log report and relevant assumptions. The data collection consists of the height of slope, slope angle, fluctuation of water level, shear strength parameter, hydraulic conductivity, and surcharge load. The study's findings are that the riverbank under both drawdowns shows a trend of a slow rate reduction of the phreatic line, indicating a poor permeability of riverbank material. The minimum FOS of the riverbank for slow and rapid drawdown are 1.045 and 0.862, respectively. For slow drawdown, the minimum FOS occurs at 12.8 days, while for rapid drawdown, the minimum FOS occurs at 0.25 days. Furthermore, in the early days, the rapid drawdown reaches its lowest FOS, while the slow drawdown still has a high value in the FOS. However, the slope stability condition for both drawdowns is nearly the same in the long term, and the riverbank takes a long period to achieve a stable condition as before. In conclusion, the drawdown event can cause slope riverbank failure, and the seepage and stability analysis using GeoStudio can view the riverbank condition during the drawdown event.