INFLUENCE OF LOCALIZATION OF SEEPAGE FLOW GENERATED IN BREAKWATER MOUND UNDER STEADY FLOW ON SCOURING

Abstract

 In this study, effects of seepage flow on breakwater mound scour are discussed using hydraulic model experiments, Particle Image Velocimetry (PIV) analysis and seepage flow analysis. In particular, we focused on spatial water pressure change caused by tsunami flow being resisted by riverbed waves and breakwater. Piezo head distribution on the ground surface was measured, and the characteristics of the seepage flow behavior were evaluated by steady state analysis using it.

 As a result, it was confirmed that the seepage flow occurred in the ground, and it was found that moving velocity of the seepage flow was different depending on size of riverbed waves. In addition, in the mound ground, the seepage flow is localized at mound shoulder of lower part (harbor inside), and flow velocity that soil particles are suspended is obtained, indicating possibility of promoting scouring. With regard to failure mode of actual breakwater mound, it has been found that location and size of seepage failure can be identified with a higher accuracy than conventional analysis method by simply performing seepage flow analysis considering water pressure change.