Vertical behavior of a suction caisson using state-dependent sand friction angles

Abstract

The vertical bearing capacity of the suction caissons is vital to the safety of marine jacket foundations. The sand friction angle is a key parameter for calculating the vertical bearing capacity. The sand friction angle is state-dependent, which is affected by the compact state and stress state. However, this effect is neglected in the current study, resulting in deviations in the calculation results of the vertical bearing capacity. Therefore, a novel method is preliminarily proposed to account for this impact while evaluating the vertical bearing capacity of suction foundations. First, a new friction angle is expressed as a function of relative density and soil depth, which differs significantly from the commonly used constant friction angle. The state-dependent sand friction angle is available. Then, the general and simplified vertical bearing capacity formulas are clarified. Four key parameters in the former and a new first-order coefficient in the latter are identified. The calculation procedure based on the new friction angle is also specified. Finally, combined with model tests, a comparison study is carried out. The results show that the calculation results using the new friction angle are more accurate and practical. This study can provide a reference for the foundation design.