LOAD SETTLEMENT RELATIONSHIPS FOR CIRCULAR FOOTINGS CONSIDERING THE DILATANCY CHARACTERISTICS OF SAND

摘要

To elucidate the mechanical properties of load-settlement relationships for spread foundations on sand, experimental and analytical studies of the strain hardening and dilatancy of sand are needed. Here we present theoretical properties derived from experiments using a circular footing model and computer simulations. The experiments were performed by vertically loading the circular footing when resting on sand, and used the relative densities of the sand and the tank dimensions as parameters. The quantitative relationships between load and settlement were analyzed with Finite Element Method (FEM) simulations using an SMP-Cam-Clay model, which can estimate sand dilatancy. The results are summarizedas follows: with both dense and loose sand models, before reaching the ultimate load, the load-settlement relationship obtained via FEM simulation agreed with that obtained by experiment. After reaching the ultimate load, the load-settlement relationship obtained from the experiment agreed with "Terzaghi' shearing capacityline". With the medium-densesand models, some binding effect caused by the soil tank rectangle was observed, possibly due to the positive dilatancy of the sand, which steadily occurred as the settlement progressed.