Abstract:
NCHRP Synthesis 418 (2011) entitled, “Developing Production Pile Driving Criteria from Test Pile
Data†details the complexity in occurrence of pile skin resistance and pile tip resistance at different
times and hammer blows during pile driving operations. With increasing usage of High Strain Dynamic
Testing (HSDT) the engineering community started paying more attention to the dichotomy between
skin and tip mobilization. To overcome the dichotomy limitations of HSDT, NCHRP recommends, “the
use of superposition to combine the back-calculated tip resistance from a blow on initial drive or from
redrive with the back-calculated skin resistance from the early blows at the beginning of restrikeâ€. The
current technologies are unable to evaluate independently the Skin and Tip resistances. This paper
discusses advancements of science and technology to achieve this goal. With sensors embedded at the
pile top and tip, the data collected is analyzed in state-of-the-art FDOT Method. This process enables
determination of skin and tip resistances independently for each blow. Independent tip and skin
resistances each with Resistance Factors can be summed up to obtain true total pile resistance. The
benefits of separate skin and tip capacities include determination of deep foundation skin resistance lost
due to scour, due to pre-drilling/preforming for pile installation, determination of uplift tension
resistance and increased quality control/quality assurance through100% testing., Accelerated
construction, life cycle monitoring and asset management of foundations are other benefits.