Effect of prior loading cycles on vertical bearing capacity of clay

The strength of a foundation on soft clay rises over time due to consolidation under the applied load. This effect can be advantageous in design. Previous studies have identified relationships between the level of monotonic vertical preload, as a proportion of the initial bearing capacity, and the subsequent consolidated bearing capacity. This study explores the influence of cycles of preloading by way of centrifuge model tests, and shows that repeated preloading leads to a further gain in bearing capacity. The gains are more significant if the preloading involves two-way cycles. For the cases explored in this study, the cyclic effect typically adds 50% to the gain in bearing capacity caused by the same preload applied monotonically.