SEEPAGE FLOW CHARACTERISTICS AFFECTED BY THE PERMEABLE LAYER AS A COUNTERMEASURE OF SLOPE SINKING BEHIND THE SEAWALL UNDER STORM WAVES

Abstract

 A moving bed hydraulic model experiment was conducted to investigate the slope sinking that occurs on the slope behind a seawall on a coastal roads during high waves under wave (non-overtopping)-groundwater level interaction conditions. The flow characteristics in the sand layer were investigated using pore pressure gauges and manometers under four cases of countermeasures (permeable layer) with different widths in the behind of seawalls. Infiltration and exfiltration flow components into the sand layer were calculated using a pore water pressure gauge measurements. These seepage velocity was analyzed using groundwater gradient and Darcy's law based on manometer measurements. The present results indicated that the cross-sectional shape of the buried permeable layer not only drains groundwater effectively but also suppresses the effects of infiltration and exfiltration into the sand layer.