Case Histories of Driven Tubular Steel Piles on Road Projects
Henry Zhang and Giammaria Gentile
Large diameter open-ended driven tubular steel piles (DTSP) have become a popular foundation type on transport infrastructure projects in the past decade or so in Australia. DTSP has been widely used on a few major highway projects on the East Coast of Australia, including the Macleay River and Floodplain Bridge near Kempsey, the recently completed $5b Woolgoolga to Ballina (W2B) Pacific Highway upgrade, on which DTSP up to 2.4m in diameter and 65m in length were installed on three major river bridges, and the under construction Nowra Bridge Project on the Princes Highway. However, this pile type is relatively new compared to traditional bored piles and smaller size driven precast concrete piles. There are limited references for driven tubular steel piles especially in rock. The authors have observed the designers’ reluctance of using DTSP even in favourable ground conditions and project engineers’ lack of experience in the field on installation, verification and interpretation of the testing/monitoring results which sometimes caused project delay and associated commercial dispute. These are the frequently asked questions about DTSP by both designers and contractors: what’s the allowable set? Can we stop piles in soils? Can we rely on plug for bearing capacity? Can we drive piles into high to very high strength rocks? Can these piles penetrate the thick dense gravel layer before reaching the rock? Can these piles be driven in hard rocks without damaging the toe? How to interpret PDA test results and PDM monitoring results to verify pile capacity and integrity in the field? The presenters have the privilege of working on a few major highway bridges where DSTP was used as key foundation type and built a large PDA test database of over 400 piles with various diameters founding in soils to hard rock in the past 10 years. In this technical talk they will share with the audience on the following:
- Advantages and limitation of DTSP;
- Construction Practice, Challenges and Innovations;
- Design Practice, Challenges and Innovations;
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