Centrifuge modeling of suction bucket foundations for platforms under ice-sheet-induced cyclic lateral loadings

This paper presents the results of a series of centrifuge model tests performed to study the behavior of suction bucket foundations for a tension leg platform in the Bohai Bay, China. The target lateral loadings were from ice-sheet-induced structural vibrations at a frequency of 0.8-1.0 Hz. The results indicate that excess pore water pressures reach the highest values within a depth of 1.0-1.5 in below the mud line. The pore pressures and the induced settlement and lateral displacement increase with the amplitude of the cyclic loading. Two failure modes were observed: liquefaction in early excitations and settlement-induced problems after long-term excitations. (c) 2006 Elsevier Ltd. All rights reserved.

Physical and numerical modeling of horizontal gas-hydrate wells

Methane hydrate, which is usually found under deep seabed or permafrost zones, is a potential energy resource for future years. Depressurization of horizontal wells bored in methane hydrate layer is considered as one possible method for hydrate dissociation and methane extraction from the hosting soil. Since hydrate is likely to behave as a bonding material to sandy soils, supported well construction is necessary to avoid well-collapse due to the loss of the apparent cohesion during depressurization. This paper describes both physical and numerical modeling of such horizontal support wells. The experimental part involves depressurization of small well models in a large pressure cell, while the numerical part simulates the corresponding problem. While the experiment models simulate only gas saturated initial conditions, the numerical analysis simulates both gas-saturated and more realistic water-saturated conditions based on effective stress coupled flow-deformation formulation of these three phases. © 2006 Taylor & Francis Group.