Reinforcement of River Embankment against the Nankai Trough Earthquake

抄録

In the Great East Japan Earthquake of 2011, many river embankments were damaged by strong seismic waves. After the earthquake, tsunami spilled over damaged embankments. In the river levee, back covering coatings were damaged due to settlement of fill by the earthquake motions or liquefaction, and back covering coatings and fill soils flowed out backrush. As a reinforcement method for river banks, a construction method of placing sheet piles in the embankment wall body is being studied for the purpose of maintaining the function of the levee at the time of an earthquake or flood. The occurrence of the Nankai Trough earthquake is expected in Kochi Prefecture, and the prefecture is proceeding with countermeasures under the idea of triple protection. Especially reinforcement of river embankments is an important issue in disaster prevention and reduction. In the past, with respect to various reinforcement methods in river embankment, dynamic centrifugal model experiments and behavior by effective stress method are being verified. In this study, we conducted a model experiment of double wall sheet piles on shoulder of cut-off wall method. In addition, model experiments were also conducted on a floating structure that keeps embedded depth of sheet piles in the liquefaction layer and shorten embedded depth for the purpose of cost rationalization of the present construction method. Furthermore, the relationship with the dominant period of the earthquake was also investigated for these experiments.