Characterisation of sand-steel interface shearing behaviour for the interpretation of driven pile behaviour in sands

Abstract

The installation and loading of steel piles driven in sands modifies both the piles' surface topography and the characteristics of the granular materials present adjacent to the pile shaft. Large-displacement ring shear interface tests incorporating pre-conditioning stages are capable of reproducing such physical processes in the laboratory and can generate case-specific interface design parameters. This paper summarises laboratory research that characterised the interface shearing behaviour of three natural sandy soils retrieved from field test sites (Dunkirk, France; Blessington, Ireland; Larvik, SE Norway) where extensive piling studies on micro and industrial scale driven piles have been carried out. The programme examined the influences of soil characteristics (physical properties and chemical compositions), interface type (mild steel or stainless steel) and surface roughness, and highlighted the significant effects of normal effective stress level and ageing time duration. Remarkable trends of increasing interface friction angles with elevated normal effective stress levels and prolonged ageing were observed. The results from supplementary small-displacement direct shear interface tests and triaxial tests are also reported. The experiments are interpreted with reference to earlier studies to develop an overview of interface shearing characteristics between steels and sandy soils and provide important insights into the mechanisms of axial capacity increases applying to steel piles driven in sands.

Evolução da transferência de carga e set-up de fundações por estacas tubulares metálicas cravadas: estudo de caso

“…Em solos argilosos este efeito é geralmente atribuído à dissipação do excesso de poropressão causado durante a instalação das estacas (Axelsson, 2002;Komurka et al, 2003). Em areias, o set-up pode ser conferido a três fatores principais: redistribuição das tensões levando ao aumento das tensões efetivas radiais, dilatância da areia com aumento da rigidez na interface solo/estaca e processo físico-químico em torno da estaca (Liu et al, 2019).…”