On the shaft capacity of non-displacement piles in sand from centrifuge tests

The compression shaft capacity of isolated piles embedded in sand is generally computed using semi-empirical correlations obtained by back-analysis of full-scale loading tests; due to the lack of full scale tension loading tests, the tension shaft capacity is commonly evaluated by reducing the compression (by about 10 to 25%). With the aim to obtain a deeper insight into this matter, a large member of physical model pile capacity in tests on isolated, closed-ended, ideally non-displacement model piles, embedded in medium and high density specimens of fine silica sand, axially loaded in compression and in tension, using the ISMGEO geotechnical centrifuge, have been analysed. Effort was investigated to evaluate the effects of the grain size, the acceleration field and the arching, on the peak shear stress resistance mobilised at the pile-soil interface.