A comparison of static and dynamic pile test results R.E.Riker

dynamic and static tests were performed on a 40 m long, 510 mm square, prestressed, precast concrete pile, instrumented with strain gages and telltales. The objective of the tests was to determine the maximum design load considering capacity and settlement. The soils consisted of about 40 m of estuarine deposits overlying siltstone bedrock. The presence of a layer of compressible silt directly over the siltstone dictated the use ofpile foundations driven to develop a high capacity in the siltstone. An important part of the testing programme was the determination of load distribution in the pile during the static test. The pile was jetted through the upper about 30 m and, then, driven to termination in the siltstone. Dynamic measurements were taken during initial driving and restriking (trvo days after EOID). A static loading test was carried out ten days after the restriking. A comparison of the results of dynamic and static analyses how that (1) only very little shaft resistance occurred in ajetted zone, (2) the shaft resistance in the lowest soil layer, the silt stratum, was found to be much smaller in the CAPWAP analysis of restrike data than in the analysis of the static test, suggesting incomplete soil set-up at the restriking event, and (3) the toe resistance mobilized in the CAPWAP at a toe movement of about 6 mm (0.23 inch) was much smaller than the toe resistance mobilized in the static loading test at a toe movement of 45 mm