Abstract:
Expansive soils pose significant challenges for lightweight structures globally resulting in billions of dollars in damages to asset owners. In Australia, the millennium drought (1997-2010) and subsequent El Nino event (2012-2016) caused severe damage to many houses built on expansive soil. According to the Victorian Buildings Authority, 5.3% of dwellings constructed during this period in the Western Suburbs of Melbourne have exhibited significant slab heave issues. Reports indicate that approximately 4,300 homeowners in the Wyndham, Melton, and Hume local government areas faced structural distress due to fluctuating climatic conditions and the resulting soil movement. These reports highlight the substantial losses incurred by homeowners due to climatic variations, which is expected to worsen in the future due to more frequent extreme climate conditions.
It is increasingly recognised that an alternative footing system tied to the stable ground with tension piles (helical anchors) would provide a solution. This system would provide confinement for the excessive heave movements and a better alternative to traditional stiffened raft footing in highly reactive soil. To determine the viability of this proposed footing system, it is essential to assess the capacity of helical anchors to resist tension, compression, and vertical deflection at various depths. However, there is very limited research on such anchoring parameters in reactive soils in Australia. This study investigates the tension and compression capacity and vertical deflection of helical anchors in clay soil at various depths. Twenty-four test piles at various depths are installed at a test pad at Koo Wee Rup, Victoria, Australia, and field testing is carried out to measure both tension and compression capacity. Installation torque is also measured, and investigated the relation between torque, compression and tension capacities.