Partially-drained loading of shallow foundations on sand

摘要

Wave loading on offshore structures that are founded on sand can result in a partially-drained response of the foundation soil. The characteristics of the rat of loaing, the permeability of the soil, and the isze of the foundation affect the degee of partial drainage. Partial drainage referes to situations where pore presures develop in the soil, and the response of the soil is neither fully drained nor undrained. This paper is concerned with the effects of loading rate, and consequent drainage, on the heavhiour of a flat circular footing that is founded on the surface of a saturated sand base. The results of physical tests perormed in the laboratory on a model-size footing are reported. The footing was founded on oil-statured fine sand and was subjected to partially-drained vertical as well as combined loading. The effect of the vertical displacement rate are reprted. The response of the footing is analysed in the context of existing drained foundation models that are based on work hardeming plasticity theory. The rate dependency of the vetrical load: defonrmation behaviour is examined in detail and the effects of rate on cimbined load yield surfaces are briefly described.