Micro-mechanical analysis of caisson foundation in sand using DEM

Abstract

Caisson foundation has been widely used for offshore structures. The micro-mechanical analysis of the behaviors of a caisson foundation during its installation, operation and failure is important but not currently available. The goal of this study is to improve the understanding of the micro-mechanisms in the installation, operation and progressive failure processes of caisson foundation and provide guidance on the design. For this, the discrete element method (DEM) is adopted to investigate the interaction of caisson foundation and sand. The DEM model is first validated by comparing the results of DEM simulations and experiments, in which similar trends are found in various load-displacement curves. With the validated model, the micro-mechanical response of soils induced by the installation process is studied firstly. Then the behavior of soils during the failure of the caisson foundation, including particle displacement, rotation, and stress distribution, are investigated for cases of different loading combinations. In addition, the fabric, including contact orientation, normal contact force, and shear contact force, and its evolution are studied by dividing the soils into four different zones based on their positions and failure mechanisms. At last, the effect of dimensionally homogenous moment to horizontal load ratio (M/(DH)) is discussed.