Axial Capacities of Drilled Displacement Piles Predicted by Spt and CPT Based Methods-Video

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Anne Lemnitzer presents a statistical analysis of axial capacity in drill displacement piles, based on load tests from 108 piles across 45 U.S. projects. The study compared methods for interpreting tests that did not reach failure and methods using CPT or SPT data to predict capacity. Surprisingly, none of the interpretation methods recommended by the International Building Code performed best. The Van der Veen criterion most closely estimated failure loads overall; Butler and Hoy was also useful but tended to be conservative. For capacity prediction, the best-performing methods varied by soil type. Bustamante and Gianeselli performed well for mixed soils, while Eslami and Fellenius was closest for clays. The researchers also found that many predictions were conservative, particularly in clays. Further work will examine how pile installation improves surrounding soil and affects axial and lateral capacity.

Keywords

axial capacity

drill displacement piles

load tests

pile capacity prediction

soil type performance