Breaking wave‐induced response and instability of seabed around caisson breakwater

Abstract

SUMMARYBreaking-wave-induced dynamic response and instability of seabed around a caisson breakwater are investigated. A seabed-rubble-breakwater system is modeled using finite elements. The impact response of the porous seabed and rubble foundation is assumed to be governed by the coupled Biot equations, and three possible formulations are considered with respect to the inclusion of inertial terms. The response is presented in terms of shear stress and pore pressure distributions at three locations underneath the breakwater. The effect of seabed and wave parameters and the inertial terms on the impact response is investigated through parametric studies. Analyses show that usually partly dynamic formulation yields the largest response amplitudes as compared to the fully dynamic formulation, which is the most complete form. The instability of seabed and rubble mound as a result of instantaneous liquefaction is also studied. Breaking wave-induced pressures in some cases are found to cause liquefaction in the rubble and the seabed. The effect of some parameters on the instability is found to be significant.

Numerical Study on Effects of the Embedded Monopile Foundation on Local Wave-Induced Porous Seabed Response

“…While the nonlinear or plastic soil behavior may be more obvious for large strains under longtime action of extreme waves, this study preliminarily focuses Mathematical Problems in Engineering 3 on the instantaneous seabed response on a relatively short time scale, for which the linear elastic concept is used as the first approximation due to its simplicity. This assumption was commonly made in the previous studies for wave-induced seabed response and gave satisfactory results [4,6,14,[17][18][19][20].…”

“…Since the excess pore water pressure is the dominant factor for liquefaction, the neglect of soil stresses at the seabed surface is considered to have little influence on liquefaction calculation. This treatment was adopted in most numerical studies [18][19][20][21].…”

A Numerical Approach to Determine Wave (Current)-Induced Residual Responses in a Layered Seabed

“…Jeng and Cha (2003) may have been the first to adopt a full dynamic model to the wave-induced soil response. This framework has been further applied to cases with caissons (Ulker, Rahman, and Guddati, 2012).…”

Two-Dimensional Model for Pore Pressure Accumulations in the Vicinity of a Buried Pipeline

“…dps dx dp* dz ( 12) (13) where V2 is the Laplace operator; G is shear modulus of soil, which is related to Young's modulus (E) and Poisson's ratio (ps).…”

“…Therefore, it is necessary to investigate first the characteristic of the initial stress condition af ter pipeline installation, and then its contribution to the liquefac tion resistance of seabed soil can be studied. The influences of preconsolidation on the soil response in a porous seabed have been reported in the recent literature [13][14][15], but only limited to breakwaters.…”