Empirical Shaft Resistance of Driven Piles Penetrating Weak Rock

John W Barrett; Luke J Prendergast

doi:10.1007/s00603-020-02228-7

Empirical Shaft Resistance of Driven Piles Penetrating Weak Rock

Rock Mech Rock Eng. 2020;53(12):5531-5543. doi: 10.1007/s00603-020-02228-7. Epub 2020 Aug 20.

Authors

John W Barrett^{1

2}, Luke J Prendergast³

Affiliations

¹ Present Address: Geosyntec Consultants, One Central Plaza, Suite 500, 835 Georgia Avenue, Chattanooga, TN 37402 USA.
² School of Civil Engineering, University College Dublin, Newstead Building, Dublin 4, Ireland.
³ Department of Civil Engineering, Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD UK.

Abstract

In this paper, an empirical relationship between the Unconfined Compressive Strength (UCS) of intact rock and the unit shaft resistance of piles penetrating rock is investigated. A growing number of civil engineering projects are utilizing steel piles driven into rock where a significant portion of the pile capacity is derived from the shaft resistance. Despite the growing number of projects utilizing the technology, little to no guidance is offered in the literature as to how the shaft resistance is to be calculated for such piles. A database has been created for driven piles that penetrate bedrock. The database consists of 42 pile load tests of which a majority are steel H-piles. The friction fatigue model is applied to seven of the pile load tests for which sufficient UCS data exists in order to develop an empirical relation. The focus of this paper is on case histories that include driven pipe piles with at least 2 m penetration into rock.

Keywords: Driven; Piles; Rock; Shaft resistance.