Bearing capacity of driven piles in sand

Abstract

A thorough review of the literature regarding bearing capacity theories and experimental studies for piles driven in sand has been made. Experimental studies indicate that the theories currently used to predict pile bearing capacity fail to consider all significant parameters. As a result of the literature review, qualitative hypotheses regarding the mechanism of pile-soil interaction are formulated and all significant parameters are identified. The unit point and side resistances obtained from thirty-four field pile load tests are used to determine which of the pile geometry and soil parameters are most significant. Bearing capacity factors are calculated and correlated with the most significant pile-soil system parameters. Three types of load test data are used: compression test data adjusted for residual stresses, unadjusted compression test data and compression/tension test data. The best and simplest correlations are developed by plotting the bearing capacity factors versus the relative depth, i. e., the depth of penetration to diameter ratio. A family of curves is obtained when the sand friction angle is included in the correlations. A gradual increase in unit point and side resistances is indicated for increasing relative depth. An error analysis of these correlations provides the basis for the conclusion that both unadjusted compression and compression/tension test correlations yield fairly accurate predictions (usually within ?? 20%) for total bearing capacity. However, the compression/tension test correlations give the best predictions for point and side bearing capacity. Recommendations are made concerning the use of the correlations developed in this study for prediction of pile bearing capacity in sand.