Vertical bearing capacity of wide-shallow bucket foundation

The criteria of vertical bearing capacity and the failure mode of a wide-shallow bucket foundation are analyzed by using model tests, finite element and theoretical methods. The finite element method (FEM) is used to study the bearing characteristics of the bucket foundation with different aspect ratios (L/D) and to analyze the failure mode of the wide-shallow bucket foundation under vertical load. The FE results are compared with those from the model tests. The load-displacement curves from numerical calculations have certain deviation compared with those from the model tests, but their overall trend is similar. The variation of loading ratio in different parts of the bucket foundation shows that the contact reaction-force of head cover, inner frictional resistance and end resistance share more than 90% of the total vertical load, so the bucket foundation and the soil inside the bucket foundation can be considered as an integrality to calculate the vertical bearing capacity. The distribution of earth pressure is given. The computational formula for the vertical bearing capacity is put forward based on the Hanson theory. The results are compared with those from FEM and model tests, and the relative error is less than 10% except that L/D=1.0. The computational formula is more suitable to the wide-shallow bucket foundation.