Bearing capacity for circular footings and suction caissons on cohesionless soil subjected to vertical loads

The calculation of vertical bearing capacity plays a crucial role in the design of suction caissons, particularly under more complex loading conditions. In this paper, a series of three-dimensional axisymmetric finite element limit analyses were carried out to measure vertical bearing capacities of circular footings and suction caissons in cohesionless soils. The empirical shape and depth factors were derived by analyzing bearing behavior of cohesionless soil. Considering the presence of friction on imaginary cylindrical retaining wall for the active–passive Coulomb wedge mechanism, the theoretical bearing capacity equation of suction caissons was established based on limit equilibrium of sliding bodies to provided new predictive solutions. The results showed that for a shallow foundation, the empirical equations obtained by regression methods can better depict the mathematical relationship between the factors (sγ, dγ and sqdq) and the affected parameters (ϕ' and L/D) as a result of that the error is less than 5%. The friction angles along virtual cylindrical retaining wall were given by combining the above empirical equations. Due to a corresponding change in surcharge load caused by the friction force acting on outer wall, the theoretical equation is relatively conservative for predicting the bearing capacity of suction caissons.