Bearing Capacity of Ring Foundations on Sand Overlying Clay

The vertical bearing capacity of rough ring foundations resting on a sand layer overlying clay soil is computed in this study by using finite element limit analysis (FELA). The sands and clays are assumed as elastoplastic models, obeying Mohr–Coulomb and Tresca failure criteria, respectively. Based on the FELA results, design charts are provided for evaluating the ultimate bearing capacity of ring foundations, which is related to the undrained shear strength of the clay, the thickness, the internal friction angle, the unit weight of the sand layer, and the ratio of the internal radius to the external radius of the footing. A certain thickness, beyond which the clay layer has a negligible effect on the bearing capacity, is determined. The collapse mechanisms are also examined and discussed.

Comparison of deformations of the large floating-roof tanks with the results of long-term monitoring

The basic requirements for settlement of steel vertical cylindrical tanks are given. The construction of such a foundation is considered and a method for calculating pile ring foundations of large- volume tanks based on the decisions of K.E. Yegorov and A.A. Bartholomei is proposed. The results of monitoring the settlement of a large-volume tank with a floating roof after the completion of hydraulic tests and three years after its operation are presented. The monitoring results are compared with the results of analytical calculations according to the proposed formulas and numerical methods (finite element method - FEM) for various software systems.