OasisLMS

A prediction survey based on the static loading test on an 18‑inch concrete-filled, closed-toe pipe pile in Mobile, Alabama attracted 74 predictions from 92 participants across 26 countries. Participants were asked to submit pile-head loading-movement curves, assess “ capacity” , and plot force distribution at an applied loading equal to their assessed “ capacity” . The event proceeded in three phases: initial predictions (“ First Go” ), revised submissions after receipt of a reference test on a near-by similar pile (“ Second Go” ), and a final capacity assessment after obtaining the actual test results (“ Third Go” ). The submissions showed a wide scatter in predicted loading-movement curves also in the Second Go after participants amended their predictions on receiving the results of the reference test. The methods of assessing “ capacity” were inconsistent, underscoring the problematic and ambiguous use of “ capacity” in practice. The survey revealed that, despite advances in analytical tools, geotechnical predictions are influenced by subjective judgment, disparate definitions, and overreliance on limited data. A reevaluation of how “ capacity” is treated in design standards and engineering practice is sorely needed. The survey results showed, in particular, a wide range of the submitted estimate of pile movement for applied loading.

Keywords:  prediction, loading-movement, capacity, test simulation, t-z /q-z curves, force distribution

B. H. Fellenius

Journal