EFFECT OF STIFFNESS OF THIN BEARING LAYER ON TOE BEARING MECHANISM OF STEEL PIPE PILE WITH A CONCRETE BULB

It has been known that the sufficiently stiff layer can be considered as a load-bearing layer of piles, even if its thickness is thin. The authors have studied the toe bearing resistance of pile on a thin load- bearing layer, in order to establish the design method about pile on a thin load-bearing layer. In this paper, the effect of stiffness of load-bearing layer on characteristics of toe resistance of steel pipe pile on a thin load-bearing layer is discussed through a series of numerical analyses. First, a field loading test of steel pipe piles with a concrete bulb on a thin load-bearing layer is reproduced through the numerical analysis, in which a soil-water coupled with an elast-plastic finite element method is applied, to confirm the availability of the numerical analysis proposed. Second, a series of numerical analyses are carried out in which the deformation modulus of the load-bearing layer and the thickness of load-bearing layer are chosen as a variable parameter. The results of the numerical analyses show that the stiffness of load-bearing layer affects the resistance when the yielding of load-bearing layer occurs.