Abstract:
Wellington Town Hall seismic retrofit showcases innovative design and the complex installation of helical piling systems for earthquake resilience in New Zealand. This challenging project involved installing 550 screw piles, each reaching up to 23 meters, to support a heritage building at high seismic risk. Wellington’s unique geological challenges—active fault lines, high liquefaction potential from reclaimed and marine soils—posed risks that required innovative helical pile design to satisfy challenging sites. We will present how helical piles provided superior performance and cost effectiveness within a challenging environment, focusing on how the installation, durability and structural resilience challenges were overcome.
The project’s innovative approach included use of high-strength materials capable of elastically withstanding both lateral and vertical loading, to satisfy strict design criteria required of the retro fitted base isolated structure. Transfer of structural loading through the various components of the pile system required careful consideration and analysis. Special attention was given to weld conformance due to the high boron content in the shafts, which necessitated advanced welding techniques and partnering with the Heavy Engineering Research Association.
Open shaft helical piles were selected to allow predrilling so that the required founding for vertical take out could be achieved. Empirical testing was undertaken to validate shaft cleanout out and grout bonding required for long term structural integrity of the pile system. Installation within a historic building with limited overhead and corridor access required innovate techniques to satisfy project requirements.
This presentation will provide valuable insights on the design of Helical Piles in New Zealand, show casing the technical challenges and the innovative solutions used to advance helical pile applications in seismically active areas, reinforcing the importance of tailored, resilient foundation systems for global engineering projects.