Analytical and Numerical Analyses on Vertical Site Responses of Submarine Permafrost in Polar Ocean

Abstract

Submarine permafrost is widely distributed in polar ocean, which has an important impact on polar engineering and subsea energy exploitation. According to the frozen porous medium theory, an analytical solution of the one-dimensional vertically dynamic response of the submarine permafrost is derived by using the Laplace transform and the separation variable method. Using the general forms of partial differential equations and the pressure acoustics module in COMSOL software, a finite element model of submarine permafrost overlying a seawater layer is established. The results show that the degraded solution agrees well with the existing results of the vertically dynamic response of the saturated soil layer in the seabed, and the analytical and numerical solutions are in good agreement. The water depth, saturation and temperature have important effects on the dynamic responses of submarine permafrost. When the soil layer is fully saturated, the water depth has a weak effect on resonance frequency. However, if not fully saturated, even a small amount of air bubbles will have a significant impact on the resonance frequency of the soil layer, and this effect increases with the increase of water depth. The effect of temperature on the nearly saturated permafrost layer is also significantly higher than that on the saturated permafrost layer.