Analyzing Drivability of Open Ended Piles in Very Dense Sands

Abstract

The successful installation of long piles driven into very dense sands relies on the occurrence of the reduction in local friction with increased pile embedment, a phenomenon known as 'friction fatigue'. The underlying mechanisms controlling friction fatigue are poorly understood, with some design methods including an adjustment for the influence of pile diameter while others do not. This paper back calculates the installation resistance of 0.356m to 2m (14in to 78in) diameter open ended piles driven into very dense sands using wave equation analyses. Cone penetration test data are used to link soil properties to installation resistance. The study illustrates consistent interpretation of a variety of case histories of open ended piles driven in very dense sands using newly developed analysis techniques and normalized parameters. Results provide information on methods for incorporating friction fatigue into drivability studies as well as a discussion of mechanisms related to pipe pile installation resistance in sandy soils.

Performance of CPT-based methods to assess monopile driveability in North Sea sands

“…Predictions based on the IC-05 (Jardine et al, 2005) methodology 102 which accounts for high strength of the clay, the pile geometry, group effects and cyclic loading 103 provided much more consistent estimates of the pile resistance than standard offshore methods. 104 Schneider and Harmon (2010) proposed a pile driveability model based on the UWA-05 (Lehane et al,105 2005) method that incorporates friction fatigue and accounts for the effects of pile plugging. They note 106 that inertial effects during driving mean that the soil plug remains at or near the sea bed level during 107…”

Response2 to reviewer's #2 supplement documnet "essd-2018-51-RC2-supplement.pdf"

“…Because the term causes the shape of the shear resistance distribution to change with pile penetration, some averaging technique is necessary. Schneider and Harmon (2010) found that the shape of the shaft friction distribution had a negligible effect on the resultant bearing graph. They suggest the change in shaft capacity between two successive depth increments be used to calculate the pseudo average shaft 2.…”

“…Predictions based on the IC-05 (Jardine et al, 2005) methodology which accounts for high strength of the clay, the pile geometry, group effects and cyclic loading provided much more consistent estimates of the pile resistance than standard offshore methods. Schneider and Harmon (2010) proposed a pile driveability model based on the UWA-05 (Lehane et al, 2005) method that incorporates friction fatigue and accounts for the effects of pile plugging. They note that inertial effects during driving mean that the soil plug remains at or near the sea bed level during installation.…”

Schlagrammung von Stahlrohrpfählen für die Offshore‐Windindustrie

“…Häufig genutzt werden z. B. die Methoden nach Stevens et al sowie Alm und Hamre mit Mittelung nach Schneider und Harmon . Insbesondere in veränderlichen festen Gesteinen, z.…”

“… Verfahren nach Alm und Hamre mit Mittelung nach Schneider und Harmon , Verfahren nach Schmertmann mit Bodenklassifikation nach Robertson et al , Verfahren nach Stevens et al mit Bezug auf das API . …”