抄録
Assuming the relation between the settlement and the skin friction of an elastic pile in homogeneous clay, the process of loading, unloading and reloading is studied theoretically. The behaviors of the settlements, the elastic recovery of tne settlements and the residual settlements at the top and the point of the pile are shown, related to the distributions of the skin friction, i.e., elastic, elastic-plastic and plastic distributions. The distributions of the skin friction, the axial compressive strain and the settlement along the pile when the pile is loaded and unloaded are shown. When the pile is unloaded, the residual skin frictions act downward at the upper part of the pile and upward at the lower part, being in equilibrium as a whole. Accordingly, the residual axial force and the residual compression of the pile shaft exist. Furthermore, considering the rigidity of the point resistance, the settlement behaviors of the friction pile and bearing pile are compared. The larger is the rigidity of the point resistance, the steeper are the gradient to the settlement axis of the load-settlement curve and that of the load-residual settlement curve, and the less is the change of the gradients of them.
