파랑-해저지반-잠제의 상호작용에 따른 지반과 구조물의 동적응답 및 액상화 대책에 관한 수치해석

Abstract

In case of the seabed around and under gravity structures such as submerged breakwater is exposed to a large wave action long period, the excess pore pressure will be generated significantly due to pore volume change associated with rearrangement soil grains. This effect will lead a seabed liquefaction around and under structures as a result from decrease in the effective stress. Under the seabed liquefaction occurred and developed, the possibility of structure failure will be increased eventually. In this study, to evaluate the liquefaction potential on the seabed quantitatively, numerical analysis was conducted using the expanded 2-dimensional numerical wave tank model and the finite element elasto-plastic model. Under the condition of the regular/irregular wave field, the time and spatial series of the deformation of submerged breakwater, the pore water pressure (oscillatory and residual components) and pore water pressure ratio in the seabed were estimated. Although present results are based on a limited number of numerical simulations, one of the study’s most important findings is that a more safe design can be obtainable when analyzing case with a regular wave condition corresponding to a significant wave of irregular wave.

Also, This study suggested a concrete mat for preventing the seabed liquefaction near the submerged breakwater. The concrete mat was mainly used as a countermeasure for scouring protection in riverbed. According to installation of the concrete mattress, the time and spatial series of the deformation of submerged breakwater, the pore water pressure, and the pore water pressure ratio in the seabed were investigated. Their results were also compared with those of the seabed unprotected with the concrete mat. The results presented were confirmed that the liquefaction potential of seabed under the concrete mattress is significantly reduced. Although present results are based on a limited number of numerical simulations, one of the study’s most important findings is that a safer design can be obtained when analyzing case with a regular wave condition corresponding to a significant wave of the irregular wave.