The Study of the Influence of Different Drained Conditions for Seabed Stability Under Wave Loading

A series of partial drained dynamic triaxial test were performed to understand the seabed stability under wave induced wave loading. In order to evaluate the real behavior of the strength of sea bed soil under wave action, the field sands in Kinhu were adopted in the study. The specimens were prepared by multi-pluviation through water method to simulate the particle aggregation in-situ. The marine soils stress states were simulated by Ko consolidation in laboratory. Moreover, the stability of marine sands is discussed under different drained conditions by using flow valve to control the soil drained states. In this study, the typhoon waves induced loading were simulated in small amplitude wave and Stoke’s 2^nd order wave theory to evaluate the cyclic stress ratio in sea bed. From the test results found that the marine soil was liquefaction immediately by using the Stoke’s 2^nd order theory. The drained efficiency is defined in this study. The relationship between strain, cyclic numbers, and cyclic stress ratio (CSR) were discussed under different drained efficiency conditions. Under the drained efficiency is 86% and the number cycle is one, the double amplitude strain (DA) of seabed soil will induce 10% by Stoke’s 2^nd order wave theory induced the cyclic shear stress ratio. But under the drained efficiency is 100%, the DA of seabed soil will only induce 7%. Combined with the time concept of wave action, when the seabed soil reach to DA = 10% under wave loading, the time of wave action request 1296 sec. From the results indicated that the drained efficiency have significantly influence on deformation resistance of sea bed soil. Therefore, the study analysis could be provided the reference for near shore structure design and engineering practice, and reduce storm induced damages.