Effect of vertical seismic motion on the dynamic response and instantaneous liquefaction in a two-layer porous seabed

Abstract

The evaluation of seismic-induced response in the porous seabed is a fundamental problem in geotechnical and coastal engineering. Although the ground motions generally include both horizontal and vertical components, most previous theoretical investigations assumed vertically propagating shear waves in a horizontally layered soil-rock system and simply ignored the effect of site response to vertical earthquake motion. In this paper, the dynamic response and instantaneous liquefaction of porous seabed, induced by vertical earthquake loading, is studied using an analytical method. The seabed is treated as a two-layer poro-elastic medium and characterized by the fully dynamic formulation of Biot theory. The analytical solutions for the response variables, such as induced displacement, pore pressure and vertical effective stress, are respectively derived and the mechanism of instantaneous liquefaction in the liquefiable sediment is investigated based on the excess pore pressure criterion. A set of parametric analysis is carried out to discuss the effects of seawater, seabed and earthquake parameters on the seismic response and maximum liquefaction depth. It is worth noting that the properties of surface seabed layer have significant influence on the seismic response and consequently the potential stability of the seabed, which is important in the analysis of foundations for offshore structures.

Effects of confining‐pressure dependent Lame moduli on the frequency‐dependent amplification of a poro‐viscoelastic soil layer under horizontal cyclic loading

“…In the engineering design and construction of geotechnical structures, it is essential to accurately evaluate soil behavior subjected to various dynamic or cyclic loads (e.g., seismic loads, wave loads, and traffic loads [1][2][3][4][5][6][7] ). Dynamic behavior differs from static behavior under dead loads in that the effects of inertia and viscous terms on the equations of motion cannot be ignored; thus, some issues are peculiar to dynamic behavior, such as appropriate modeling of viscous effects and the influence of loading frequency.…”

“…[8][9][10][11] Based on Biot theory, many researchers [12][13][14] have presented analytical solutions to one-dimensional problems of a saturated poroelastic soil column. Recently, Chen et al 4,6 presented a series of analytical solutions for the dynamic response of a nearly saturated seabed subjected to vertical seismic loading. However, several studies 4,6,[12][13][14][15][16] on Biot theory only considered viscous coupling 17 because of the interaction between the solid skeleton and pore fluid, assuming that the material behavior of the solid skeleton is purely elastic.…”

On the Slope Stability of the Submerged Trench of the Immersed Tunnel Subjected to Solitary Wave

“…Seismic load and wave load are two common types of marine environment loading. The effects of seismic load acting on a seabed or an offshore structure attracted a great deal of attention in the past decades [2][3][4][5]. Although the wave load is more common compared with the seismic action, the attention paid to the submarine slope under wave loading is not enough.…”

Frequency‐dependent dynamic behavior of a poroviscoelastic soil layer under cyclic loading

“…With the rapid development of construction engineering, soil is subjected to various dynamic loads in practical engineering, such as seismic loads, wave loads, and traffic loads . Under these loads, the soil is prone to deformation or destruction, which may lead to major disasters such as foundation subsidence and structural instability .…”