ACE Geosynthetics Inc. Taichung City, Taiwan
Producer: ACE Geosynthetics Inc.
Supplier: ACE Geosynthetics Inc.
Please describe the project specifications
The Irrawaddy River in Myanmar is an important river running through Myanmar. Due to the river deepened by mining and global warming, the surge rate and the flow rate of the river increases yearly every rainy season, leading to much of the land on both sides of the river to be washed away. Hence, many of the ancient village settlements or monuments near the shore have disappeared, and many villages are waiting to be forced to move out. The Myanmar government considered the necessity of preserving historical culture, and the huge financial expenditures in moving villages; therefore, the Myanmar government began to try various construction methods to protect the riverbank. This project is located in the settlement of the sandbank village along the Irrawaddy River on the northeast side of Mandalay. The riverside revetment of the village also faced the same problem, and the government attempted to protect the riverbank using the method of stone and sandbags, but many riverbanks were still washed away. In the end, the government decided to adopt the method of ACEFormer™, which has never been applied in Myanmar, to protect the river revetment. ACEFormer™ is typically a flexible geotextile mattress made from two layers of high strength PP and/or PET woven geotextiles, using the cement mortar as filling material, which can be applied to the surface without terrain restrictions. ACE Geosynthetics analyzed and designed the appropriate size of ACEFormer™, which can effectively resist the river from erosion after being filled with cement mortar and hardened. In addition, with the special design of roughened surface, the current impact energy of the river is reduced, thereby increasing the slope stability.
What was the purpose of this project? What did the client request?
The length of the riverbank of the project is 900ft. In order to avoid the skyrocketing during the rainstorm and the high-speed river current continuing to wash away and attack the riverbank, causing the retreat of shorelines and affecting residents’ safety and property threats, the local government hoped to have a safe, economical and durable solution to prevent the livelihood problems caused by large-scale village relocation because of the constant loss of the soil in the village.
What is unique or complex about the project?
1. The Irrawaddy River has a very wide water basin, and the government hoped to expand the scope of protection as much as possible. Therefore, the targeted slope length of the riverbank is 90ft, around 35ft above the water level and 55ft below the water level, the slope is 30 to 45 degrees, and the maximum water depth is around 36ft during the construction in dry season. The challenge of this project is that the slope length is very high, the slope is steep, and the water depth is extremely deep; hence, the difficulty of construction increases drastically.
2. The water flow measured on site was about 2m/sec., and because the project is located at the bending part of the riverbank with plenty of eddies, and the geology is loose sandy soil, leading to many erosion pits on the revetment slope underwater. The design company planned to fill the erosion pits with sandbags first. However, even if the sonar was used to confirm the topography as accurate as possible before construction, many undetected erosion pits were still found during actual construction. Thanks to the flexibility of the geotextile mattress, ACEFormer™ can be applied to the uneven terrain and fill the erosion pits.
3. Due to the above special circumstances, large-sized geotextile mattress with a width of 60 ft and a length of 90 ft made of a single-piece processing was adopted to conduct the construction to reduce the complexity of the underwater working interface.
4. The time period between the release of the government budget and the arrival of the rainy season was only five months. During this short period, the design, production, process and delivery of the products, preparation of equipment and filling material, and together with construction should be finished. Hence, this project was under extremely high time pressure.
5. In summary, the challenges of the project are the high floating of the geotextile mattress before filling due to the deep-water depth, and the heavy weight of the geotextile mattress after filling because of the large size of the single unit. Thus, the anchor method and configuration of the geotextile mattress, the grouting equipment and the flow rate must be calculated carefully to ensure that the geotextile mattress can be successfully installed in a short time. Furthermore, the design of the geotextile and the ratio of cement slurry were also adjusted to reduce the loss of filling material caused by the water flow.
6. After the installation, in order to avoid the seam joints between the geotextile mattress from erosion by high flow rate during the raining season, the overlap of the geotextile mattress was also specially designed to reduce the risk of damage.
What were the results of the project?
1. Construction: ACEFormer™ is suitable for all terrains and is easy to install, especially for deep water construction; hence, the project can be completed within the scheduled time period.
2. Function: The filled ACEFormer™ resists the erosion damage caused from the river, effectively achieves the purpose of river protection, and thus avoids the necessity of moving out the village.
3. Cost: Because ACEFormer™ is easy to install and does not require large machinery, the costs of construction and material transportation are greatly reduced compared to the traditional method.
4. Additional value: The local residents are quite satisfied with the unique concave and convex surface of ACEFormer™, which has become part of their waterfront living activities.
Content is submitted by the participant. IFAI is not responsible for the content descriptions of the IAA award winners.