Design of an instrumented model pile for axial cyclic loading

When choosing the pile diameter the “scale effect” must be considered, as it is linked to the ratio of the pile diameter (B) relative to the mean size (d50) of the soil particle. The “scale effect” appears as a growth of the resistance of the pile to tension loading, hence the skin friction, when the pile diameter is small (Garnier & König 1998). When the ratio (B/d50) increases, we are close to the prototype case and it reduces particle size effect and hence the “scale effect”. The main difficulty is to know at which ratio no “scale effect” is observed. The “scale effect” has been discussed by many people but no consensus has been found (Garnier 1995; Foray et al. 1998). Balachowski (1995) suggests that when the ratio B/d50 is higher than 250, no “scale effect” is observed; Garnier & König (1998) advise a ratio of 100 and Fioravante (2002) a ratio of 50.