ABSTRACT

Marine geotechnical engineers have extensively studied the phenomenon of wave-seabed interaction problems in the last decades. Most previous investigations have focused on the quasi-static soil behavior, because of the complicated mathematic procedure associated with dynamic behaviors. However, the influence of dynamic soil behavior on the wave-induced seabed response cannot always be ignored under certain combination of wave and soil conditions. In this paper, an analytical solution for the wave-seabed interaction with dynamic soil response is derived. Numerical results demonstrate the significant effects of dynamic soil behavior on the wave-induced seabed response. The applicable range of the present solution will also be clarified.

INTRODUCTION

Recently, the phenomenon of the wave-seabed interaction problem has attracted attentions from marine geotecbnical and coastal engineers. The reason for this growing interest is that many marine structures have been reported to be damaged by waveinduced seabed instability, rather than from construction causes. (Silvester and Hsu, 1989). Since the 1970's, numerous investigations related to the wave-induced seabed response have been undertaken. Since the completely dynamic analysis for the wave-seabed interaction is too complicated, most previous investigations have been limited to quasi-static analysis (Madsen, 1978; Jeng, 1997). Recently, Jeng et al (1999) derived an analytical solution for such a problem with a u-p dynamic form based on Biot's poro-elastic theory (Biot, 1960). They concluded that the inertial effects on pore pressure are significant in shallow water. However, the u-p dynamic approximation undertaken by Jeng et al., (1999) did not include the second time derivative of the relative fluid displacements. It is expected that the acceleration term due to fluid displacements is important for large wave loading. Zienkiewicz et al (1980) investigated the influence of dynamic soil behavior based on one-dimensional analysis. They concluded that the dynamic soil behavior is not important for the wave-induced soil response.

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