Preliminary study on the water film at the soil–structure interface under cyclic loading

Abstract

Offshore foundations usually experience long-term cyclic loading, where the weakly bound water at the soil-structure interface can be transformed into free water. The free water enriched at the soil–structure interface would influence the mechanical characteristics of the soil near the interface, weakening the interface strength and posing a significant threat to the safety and stability of offshore foundations. This study proposed a novel concept, i.e. the characteristic water film thickness, to quantify the enrichment degree of water film at the soil–structure interface under cyclic loading. A series of cyclic shearing tests were carried out by using self-developed cyclic loading equipment combined with a small constant temperature centrifuge. The influence of different clay and salt contents on the characteristic water film thickness was investigated and analyzed. It was found that both the kaolin and salt contents significantly impacted the characteristic water film thickness, where it was positively correlated with the kaolin content while negatively correlated with the salt content. The research outcome enriched the understanding of the weakening mechanism underlying the load and deformation transfer between soil–structure interface.