Evaluation of Piles' Ultimate Capacity utilizing Direct CPT Methods Considering Consolidation and Aging Setup-Paper

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This study evaluates how consolidation and long-term aging increase the axial capacity of driven piles, particularly shaft resistance, and whether these effects can be incorporated into direct cone penetration test (CPT) design methods.<br /><br />The researchers developed separate time-dependent models for consolidation setup in Louisiana clay and aging setup in clay and sand. Consolidation setup was assessed using instrumented Louisiana piles and measurements of excess pore-water-pressure dissipation; additional resistance after dissipation was attributed to aging. Literature data from 17 case studies informed the aging models. The resulting setup parameters were 0.53 for consolidation in clay, and 0.23 and 0.16 for aging in clay and sand, respectively.<br /><br />Eight direct CPT methods were evaluated. Their resistance estimates at 14 days after installation were adjusted using the setup models and compared with field measurements. The CPT methods provided fair estimates of clay shaft resistance at the end of consolidation, without needing changes to the methods themselves. However, all generally underestimated measured resistance in clay.<br /><br />Aging produced further capacity gains beyond consolidation. Applying the aging models improved predictions, although estimated shaft resistance varied by CPT method: predicted-to-measured ratios ranged from 0.76 to 1.29. Most methods overestimated end-bearing resistance. Overall total-capacity predictions were most accurate with the Philipponnat and UF methods.<br /><br />The findings show that consolidation and aging are distinct contributors to pile setup and that accounting for both can improve long-term capacity estimates. The authors suggest these gains could support less conservative pile designs and the reuse of existing foundations, while noting the need to estimate long-term resistance reliably.

Keywords

pile setup

axial capacity

shaft resistance

consolidation

aging

driven piles

cone penetration test

CPT design methods

clay and sand

long-term capacity