Stability of sand tube seawall as a tsunami protection

Tsunami height cannot be predicted accurately. When under predicted, tsunami may overtop a tsunami wall that is aimed at mitigating the disaster. The consequence is huge especially when the wall collapse. A lesson learned from the East Japan tsunami in 2011 should be considered seriously to improve the way of protecting the coastal area from tsunami disaster. Large concrete seawalls along the coast have been partly destroyed by the tsunami. The seawall failures modes were drifted away or overturned due to heavy scours behind the seawall. Concrete seawall is expensive as well as unnatural which sometime does not go with the environment or landscape. Model of sand tubes wall is proposed for tsunami mitigation. The wall is constructed using fabric-tubes filled with sand. In area where the coast is sandy, it should not be difficult to find such material for the construction. Physical model was used to study the performance of the sand tube sea wall against tsunami. The height of the wall was varied. The tubes were placed in layers to create sand tube walls of trapezoidal shape. The sand-tube walls were than tested under tsunami attack in the Hydraulic Laboratory of Department of Civil and Environmental Engineering Universitas Gadjah Mada. The tsunami hydrograph model was set to represent a type of hydrograph recorded during the East Japan Tsunami. The results showed that sand tube seawall with sufficient sizes can be used as a tsunami protection. Sufficient protection is required to avoid scour at the rear toe of the wall. © 2020 22nd Congress of the International Association for Hydro-Environment Engineering and Research-Asia Pacific Division, IAHR-APD 2020: "Creating Resilience to Water-Related Challenges". All rights reserved.