Experimental study of different breaking waves impact on sandy seabed

Breaking wave has significant influence on the offshore coastal topography and offshore structures. Based on the physical model experiments,the bed form and pore water pressure are analyzed in the wave broken zone under the solitary wave and regular wave. Under breaking wave impact,the seabed surface scour is more heavily. Sandbar and sandpit are formed at the wave broken zone,and their scales are larger and the amplitudes of pore water pressure are higher under the solitary wave compared with regular wave. At the same time,effect of the variation of wave surface on the pore water pressure was studied. It is found that the duration curves of wave surface changing are similar to the duration curves of pore water pressure and it is more similar to the duration curves of pore water pressure gradient. It shows that the variation of wave surface can mostly reflect the variation of pore water pressure gradient on the seabed. Based on the discuss of the coupling effect between wave and seabed,it is found that topography variation may lead to waves appear different broken types at the wave broken zone,it was concluded from analysis that the pore water pressure amplitude under the plunging wave is bigger than spilling wave.