A Review of Residual Load Development In Driven Cast-In-Situ Piles-PPT Presentation

PPT Presentation

Pdf Summary

The presentation examines residual load development in driven cast-in-situ (DCIS) piles. Although residual loads are well documented in driven precast piles, DCIS piles may also develop them because their large-displacement installation involves both driving and concrete casting.<br /><br />A case study of piles A3, A4, B5 and B6 used strain measurements to assess temperature effects and residual loads. Concrete hydration mainly affected gauge readings during the first 10 hours; compressive strains then became dominant. The observed net compression was attributed to concrete shrinkage during cooling and consolidation of soft soils. Shallow gauges recorded high compressive strains, considered largely structural rather than geotechnical. Gauges in the founding sand showed less compression than those higher up, possibly due to groundwater absorption. Residual strain remained relatively constant over time, although strain changes had not stabilised by testing.<br /><br />Residual loads in DCIS piles can arise from excess pore-water pressures in cohesive soils and their subsequent consolidation, as well as internal concrete processes such as setting, hydration, cooling and curing. These curing-related strains may have limited influence on ultimate-state design but can significantly affect shaft friction and bearing load–strain behaviour in serviceability assessments. The presentation also notes that the Siegel and McGillivray method is consistent with the Unified Design method.

Keywords

residual load

DCIS piles

driven cast-in-situ

strain measurements

concrete hydration

concrete shrinkage

shaft friction

bearing capacity

pore-water pressure

Unified Design method