Scale Effects of Ultimate Pile Capacity

Abstract

Methods of estimating the ultimate bearing capacity of piles in sand from the results of static cone and standard penetration tests are compared with the results of load tests on driven and bored piles of different sizes and embedment ratios in the sand bearing stratum. An empirical reduction factor of the ultimate unit point resistance in sand is established, which decreases with greater pile base diameter and with greater average static cone or standard penetration resistance near the pile point. Similarly, for piles in stiff fissured clay an empirical reduction factor of the undrained shear strength is established, which decreases with greater pile base diameter and is greater for driven than for bored piles. The ultimate unit skin friction of piles in a given sand or clay is practically independent of the pile diameter.