Performance of Long-Driven H-Piles in Granitic Saprolite

There has been much advancement using conceptual models and analytical methods to explain various aspects of pile performance. They are mainly based on the findings of model tests and full-scale pile tests in fine-grained and coarse-grained soils, and driven piles on land are normally less than 40?m. Design methods developed from this data bank of pile geometries and soil conditions for long piles should be treated with caution. In this paper, 13 H-piles of 34–60?m and 7,096?kN capacity founded on granitic saprolite are studied. Among them, two piles were restriked at different time intervals. All piles were axially load tested statically using a maintained load method. In contrast to the short rigid piles founded on weaker soil, their load-transfer mechanism varied with the magnitude of applied load and pile length. They deformed almost linearly at small loads and might have buckled when the loads were large and the creep settlements were found to be length dependent. Existing criteria might not be able to interpret failure loads sometimes, but a pile dynamic analyzer was found to give the best estimate on pile capacity.