Advanced numerical modelling of caisson foundations in sand to investigate the failure envelope in the H-M-V space

Abstract

This paper focuses on the identification of the failure envelope of a caisson foundation in sand using an advanced critical state-based sand model (SIMSAND) and the Combined Lagrangian Smoothed Particle Hydrodynamics Method (CLSPH). The parameters of the SIMSAND constitutive model are first calibrated using triaxial tests on Baskarp sand. In order to validate the combined CLSPH-SIMSAND approach, a cone penetration test, model tests and a field test on a reduced scale caisson foundation are simulated. After full numerical validations with different scales from laboratory to in-situ conditions, a numerical parametrical study is then introduced considering different sand properties (density, friction angle, deformability, crushability) and caisson dimensions (soil-structure contact surface area, diameter-depth ratio) and complex combined loading paths to identify the failure envelope in the horizontal force (H), bending moment (M), vertical force (V) space. The influence of the caisson foundation contact surface area, aspect ratio and soil parameters are considered and quantified. Finally, an analytical formula is proposed for the 3D failure envelope in the H-M-V space.