The Role of Geosynthetics in River Bank Erosion Control
Strong river currents, especially during heavy rainfall, effortlessly dislodge soil particles from riverbanks at undesired locations, weakening the slopes of rivers and destabilizing the involuntarily exposed foundation of riverside structures. This natural displacement of soil along riverbanks and embankments is referred to as soil erosion.
Oftentimes groins are built to encourage siltation to replenish the soil lost along riverbanks, however, these structures are also prone to scour at their base. These problems can be cost-effectively solved with the flexible high strength ACETube® geotextile tube and ACEFormer™ geo-mattress in tandem with rock filled gabion baskets.
Take a look at this 2017 IFAI International Achievement Award winning river erosion case resolved with ACE Geosynthetics ACETube® and ACEFormer™ in Taichung, Taiwan.
This project is located in Central Taiwan, at the downstream dam section of the Zhuoshui River flood plain which mainly comprises of river sediment. The river endures a high flow period throughout the rainy period from May to October during which the riverbanks are markedly prone to erosion. This results in shrinkage of the flood plain that critically threatens the stability of the river dyke. The spur dam has defense flood levels up to 24,000 m³/s and was used as river bank protection. However, due to long-term foundation erosion at the spur head, this caused the loss of soil and local settlement of the structure, which destroyed the gabion shield and exposed the pier head.
The ACETube® geotextile tube was used to protect the flood plain slope and shelter the foundation of the PC spur dam. First, a layer of polypropylene ACETube® paved both sides of the dam’s foundation to retard base subsidence. The ACETube® was then filled to different heights, or stacked together to stabilize the foundation, and to reduce the effects of scour and improve the effectiveness of siltation at the pier heads. Also, at the most severe erosion sites, gabions overspread the ACETube® and gaps were filled with local sand to amplify the overall erosion resistance of the structure. On the flood plain slopes, the ACETube® was placed and covered with the mortar filled ACEFormer™ to not only protect geotextile tubes, but also increase the entire slope strength.
Product: ACETube® -hydraulic structures, ACEFormer™
Solution: Revetments, Wing Dams / Groynes, Pier Scour Protection System
Since 2011, this project canvased more than 1,100m of the Zhuoshui River bank for the protection of flood plain slopes and several spur dams along the river. The combination of gabions with geotextile tubes for foundation scour protection, instead of solely using gabions, can save around 30-40% of the overall cost, and furthermore reduces approximately 88% of carbon emissions which emphasizes the benefit of geosynthetics in green engineering. After the remediation was completed, the shoreline extended and direct erosion of the flood plain reduced, successfully improving the safety of the embankment.
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Design Proposal – Provide drawings, specifications and cost analysis
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For more information of the case, please read the case studies.
For details about the analysis and design of the project, please contact us.
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