Laboratory Study on the Instability of Pavements due to Tsunami Flooding

Laboratory experiments were conducted to investigate the instability of pavement due to force exerted by the tsunami flood and to find methods to increase its stability. The modifications introduced to the pavement plate to increase stability were making holes, inserting fixed strip, modification of bed and bed slope. The first two modifications increased the stability, while the third modification decreased the stability and the fourth modification has no effect on the stability. The instability of the plate was checked at two different beach slope 1/29 and 1/7. It was found that, there is no significant effect on the lift force because of changed slope. It was confirmed in experiments that the plate starts to lift when the pressure gradient force between top and bottom of the plate exceeds its self-weight. The threshold head difference and velocity required to make plate unstable was found 6 cm and 0.40 m/s respectively. After making holes, the stability of the plate increased by 42% in head and 28% in velocity, up to 7 number of holes (0.20% reduction in area by hole). Upward lift force was decreased after making several holes on the plate. The stability of the plate increased by 33% in head and 20% in velocity after putting fixed strip in front of the experiment plate. The stability of the plate decreased however by 8% in head after putting coarse sand between plate and flume bed.