Centrifugal Modeling Test On Wave-induced Dynamic Response Of Seabed

In recent years, sea engineering accident occurred frequently, so researchers paid their attention on the accident cause, which include sea wind, earthquake, wave loading, floating ice’s strike, corrosion of salt and so on. In this paper, the research is focused on the modeling test of dynamic response of seabed under wave loading. The cyclic wave pressure induced by the wave loading occurs at the interface of seabed-sea, and transfers into the seabed, and leads to the change of pore pressure and effective stress. The corresponding results of the change are deformation of the seabed and even liquefaction, which causes the damage of the structure, built on the seabed. The research is developed by the means of centrifugal modeling test, which has an irreplaceable advantage in simulating prototype and has drawn more and more attention recently. Now, the first and sole drum centrifuge in China has been installed in Dalian University of Technology. The research work in this paper could be divided into two parts.The first part is mainly about the centrifugal modeling test research work on the generation of the progressive linear wave. The wave generation system includes a paddle wave maker driven by a servo motor of200W and a beach wave absorber, which is able to make progressive linear wave of different wave height and wave frequency. The wave pressure and wave fluctuation were measured by mini pore pressure transducers and a developed device to estimate the similarity with the prototype. The validity of wave generation was checked according to wave theory through analyzing many series of test results. Compared with previous centrifugal wave maker, the new system was proven that can make waves of higher height with the advantage of bigger size channel, which provides a basis for the future study on wave-induced dynamic response of seabed.The second part is mainly about the centrifugal modeling test research work on the dynamic response of seabed under wave loading. In the test, the model box was placed in the drum channel and suffered the wave loading. The seabed dynamic response could be analyzed though the data collected by the pore pressure transducers placed in the inner of seabed. The seabed model which was homogeneous was made by pouring sand uniformly using automatic sand pourer device under1g condition, and then the fake cohesive force in the model was generated by inflowing liquid into the model through the inlets at bottom of the model box. The seabed model is made of poorly graded sand, of which the average particle sized50is0.1724mm; the relative density is38.9%. Through a series of tests, it is found that the wave pressure would decay in the progress of transferring along the seabed and the smaller the seabed’s permeability is, the more the wave pressure decays. Due to the contraction, the seabed model settled under the cyclic wave loading. The pore pressure’s dynamic response reflected by the pore pressure transducers placed in the inner of seabed is in accordance with the SASSA’s research. Because of the low intensity of generated wave, liquelaction did not occur, so the next work is to do some improvement on this test.