Measured Time Effects for Axial Capacity of Driven Piling

The results of a study to quantify effects of time on pile capacity are presented herein. The main focus of this paper is to present results from a database developed from various pile tests reported in the literature and to present some observations based on the pile test data. Both sands and clays are shown to experience setup. A database containing 80 pile load tests (both static and dynamic) was collected and sorted into three groups according to the primary subsurface profile: sands, clays, and mixed soil. Capacity-versus-time relationships are plotted for each soil type, but particular attention is given to the increase in capacity of pile in sand with time. It is shown that the load test results can provide an upper-bound estimate and a lower-bound estimate. Estimating the effect of time on pile capacity in sand can be important for reuse of existing piling and also can be helpful for quantifying just how much to expect capacity to increase with time if pile load tests show that capacities are coming up short.