ABSTRACT:

The analysis of wave-induced pore pressure and effective stresses is an important factor in the design of offshore installations. However, to simplify the complicated problem, most previous investigations have ignored the effects of inertia forces. This paper presents an analytical solution to the equations governing the wave-induced seabed response, including inertia terms in the whole problem. The numerical results show that the inertia forces cannot always be ignored. The relative difference of pore pressure between the present solution (with inertia items) and the previous solution (without inertia items) may reach 17 % of po under certain combinations of wave and soil conditions.

INTRODUCTION

Recently, the phenomenon of wave-seabed interaction has been extensively studied by geotechnical and coastal engineers. The major reason for the growing interests in this problem is that many offshore installations (such as breakwaters, pipelines and platforms, etc) have been reported to be damaged by the wave-induced seabed instability in the vicinity of structures, rather than from construction causes. When ocean waves propagate over the ocean, they induce dynamic pressure fluctuations on the sea floor. These fluctuations further generate excess pore pressures and effective stresses, which have been recognized as dominant factors in causing the instability of a seabed (Rahman, 1997). Thus, an evaluation of the waveinduced soil response (including pore pressure, effective stresses and soil displacements) is of significant importance to marine geotechnical and coastal engineers involved in the design of foundations for offshore installations. Based on Biot''s theory (Biot, 1941), numerous theories of the wave-induced soil response have been developed since early 1940''s. Among these, Yamamoto et al. (1978) considered two-dimensional progressive waves over an isotropic and homogeneous seabed of infinite thickness. This model has been further extended to a seabed of finite thickness as well as a layered seabed (Jeng, 1997).

This content is only available via PDF.
You can access this article if you purchase or spend a download.