Wave-induced soil response in a nearly saturated sea-bed of finite thickness

Abstract

Consolidation and storage equations are used to develop a closed-form solution for the wave-induced pore pressure, soil displacements and effective stresses in an elastic sea-bed subject to a system of two intersecting waves. A homogeneous soil matrix of finite thickness in isotropic and saturated conditions only is considered. The three-dimensional general solutions so developed are readily reducible to the conditions for soil of infinite thickness, and also for the limiting cases of two-dimensional progressive and standing waves for soil of finite thickness, for which no explicit solutions have previously been available. Verification of this solution with results of two-dimensional solutions available from a semi-analytical method, a boundary-layer approximation and a numerical model is carried out. Validation is performed by comparison with experimental results. The effects on wave-induced pore pressure of sea-bed thick- ness, shear modulus of soil and grain size are discussed. Les équations de stockage et de consolidation sont à la base de la solution approchée qui a été développée et qui permet de calculer la pression interstitielle, les déplacements et les contraintes effectives régnant dans un banc marin, élastique, soumis à deux régimes de vagues sécants. On considère que le sol est homogène, isotrope, saturé et d'épaisseur fine. Les solutions générales tridimensionnelles mises en oeuvre sont facilement transposables à un sol d'épaisseur infinie ou à un sol d'épaisseur finie soumis à un système bidimensionnel de vagues progressives puis stationnaires, cas pour lequel il n'y avait, jusqu'à présent, aucune solution explicite. Cette solution a été vérifée à l'aide des différentes solutions bidimensionnelles calculées à l'aide d'une méthode semi-analytique, d'une approximation couche-limite et d'un modèle numérique. Elle est validée par les résultats expérimentaux. On étudie également l'influence de l'paisseur du banc, du module de cisaillement du sol et de la taille des grains sur la pression interstitielle créée par les mouvements marins.

Ocean waves propagating over a porous seabed: Residual and oscillatory mechanisms

“…A comparison of the present model with the existing experimental data [13] indicates that, the present analytical solution overall agrees with the experimental data. Together with previous solution to oscillatory mechanism [10] , an amplitude ratio ( ε ) is introduced to examine the role of both mechanisms. Numerical results indicate that the residual mechanism is particularly important for large wave loading, while oscillatory mechanism dominates the pore pressure under small wave loading.…”

“…The analytical solution to the wave-induced oscillatory soil response in a saturated seabed was derived by Jeng and Hsu [10] . For a saturated seabed of infinite thickness, the pore pressure ( p ) and shear stress (τ ) can be expressed as exp( ) cos( )…”

“…Numerous investigations for ocean waves propagating over a porous seabed have been carried out since the 1970s [5][6][7][8][9][10] . Among these, both mechanisms have been considered individually.…”

Pore Pressure Response of Clayey Seabed Under Ocean Wave

“…However, the existing methods do not fully reduce damage caused by wave-induced seabed instability. Therefore, considerable efforts have been dedicated to the phenomenon of the wave-seabed-structure interaction ( [2], [3], [4], and [5]). As indicated in published literatures, there are two kinds of seabed failures, namely, liquefaction and shear failure.…”

“…As indicated in published literatures, there are two kinds of seabed failures, namely, liquefaction and shear failure. When the pore pressure become excessive with accompanying decrease in effective stresses, a sedimentary bed may be move in either horizontal (liquefaction) or vertical directions (shear failure), then lead to an instability of the seabed [5].…”