Partial Safety Factors of Single Pile Capacity

From pile load-transfer analyses, it is known that the sequence of mobilization of pile shaft skin friction and that of pile point resistance are quite different. Thus determining single-pile bearing capacity with a single safety factor K is rather ambiguous, two partial safety factors, namely, one for shaft skin friction and another for point resistance, should be used instead.In this paper the load transfer of loading tests on five model piles and seventeen prototype driven and bored piles is analyzed. For these piles, curves of safety-factors Kf and Kb as functions of the degree of mobilization of point resistance a are obtained, which well represent load-transfer behavior. From the test data the Kf and Kb -（s/d）curves are also obtained, where s/d is relative settlement of the pile; from these, for K=2,ranges of Kf -and Kb -values and corresponding s/d values have been obtained, and it is hoped that these may prove to be of some value in practical design work.