THE PERFORMANCE OF SAND DUNE WITH SHEET PILE PROTECTION AGAINST TSUNAMI ATTACK
ISORA DEWANTI, Prof. Ir. Nur Yuwono, Dip.HE., Ph.D
2015 | Tesis | S2 Teknik Sipil-
Sand dunes like those located in the southern coast of Java are natural defenses that may protect the shore from tsunami surge. The degree of protection given by dune against tsunami attack depends on the size of the dune itself and the tsunami characteristic. The overtopping flow may cause severe erosion at the downstream slope of the dune, hence sheet pile installation were done to strengthen the slope and improve the dune stability. The aim of this study is to know performance of sand dune with sheet pile against tsunami attack which is important for the improvement of tsunami disaster mitigation. Both physical and numerical simulation were conducted to understand the phenomena and assess the performance of sand dune as natural protection against tsunami. Physical simulation were conducted in a wave flume which was equipped by dam break system to generate the tsunami surge. The dune models were built using fine sand. The shape of the dune models were trapezoidal with slope ratio 1:3. Three different tsunami surge height were generated by varying the basin depth (ð‘‘ð‘œ) and the height of the dune (D), ð‘‘ð‘œð·â„= 2, 3, and 4. Four sheet pile models were made from plywood with different height, 2.5, 5, 7.5, and 10 cm. The numerical model has been able to illustrate the geometry evolution of sand dune with sheet pile protection due to overtopping flow. However, the current model has several limitation due to simplification. The results indicated that the relative height of sunami (ð‘‘ð‘œð·â„) and relative height of sheet pile (ð‘†ð·â„) influence the amount of eroded material. The amount of eroded material increases when ð‘‘ð‘œð·â„ is high and ð‘†ð·â„ is lower. The installation of sheet pile at the downstream slope influences the rate of dune height reduction. Result of this study shows that sheet pile installation will maintain the dune height up to 70%.
Kata Kunci : tsunami, sand dunes, simulation, protection, scour, erosion
