A stability diagram is proposed for the design of piles in clay under cyclic axial loading. The diagram represents the allowable combination of average load (Q_<ave>) and cyclic load amplitude (Q_<amp>). The boundary lines between stable and unstable zones are defined by the following relations : (1) Q_<max>≦Q_y ; (2) 2 Q_<amp>≦Q_y ; where Q_<max> is the maximum value of cyclic load (=Q_<ave> + Q_<amp>) and Q_y is yield load obtained by pile load tests. The diagram is compared with the results of field and laboratory tests reported in the literature.
