Case Studies of Driven Tubular Steel Piles in Soils and Basalt on Woolgoolga to Ballina Pacific Highway Upgrade-Paper

Paper

Pdf Summary

The paper examines two cases of large-diameter driven tubular steel piles on the Woolgoolga to Ballina Pacific Highway upgrade, where piles were founded either in soil or highly variable basalt.<br /><br />At Byrons Lane Overpass (A32), piles designed to terminate in soil were driven 6–12 m deeper than expected. Uncertainty over termination criteria, higher-than-minimum driving energy, limited contractor experience, and differences between assumed and measured soil resistance contributed to the overlength. PDA testing confirmed required capacity and acceptable settlement; one pile could have been accepted without driving to rock.<br /><br />At Twin Bridges over Randles Creek (D10), driven piles were reconsidered after concerns that variable, locally strong basalt could damage pile toes. The design risk was managed through additional investigation and contingency pile length, thicker driving shoes, and added PDA testing. Testing confirmed adequate capacity, intact pile shafts, and low toe stresses, allowing driven piles to replace the proposed bored piles successfully.<br /><br />The cases show that driven piles can be effective in soil and variable rock, but require site-specific assessment and experienced engineering. For soil-founded piles, vibratory driving and shoes may reduce resistance and should generally be avoided unless rock is near the toe. In variable basalt, investigations must establish rock depth, strength, and thickness, while design and procurement should allow for uncertainty. The paper recommends pile-driving monitoring on every production pile and PDA testing on at least 25% to improve quality assurance and reduce disputes and delays.

Keywords

driven tubular steel piles

Woolgoolga to Ballina highway

pile foundation

soil resistance

basalt variability

pile driving assessment

PDA testing

driving shoes

quality assurance

bridge overpass