Insurance2023
Retaining Wall Collapse Investigation
Toowong, Brisbane
Overview
Forensic investigation of a 4-metre high reinforced concrete retaining wall that collapsed during a heavy rainfall event. The wall supported a residential property above a lower neighbour. Investigation revealed the wall was designed without adequate drainage, had insufficient reinforcement for the retained height, and lacked a toe key. The failure mechanism was a combination of hydrostatic pressure build-up and sliding failure at the base.
Challenges
- 01Emergency stabilisation required before investigation could proceed
- 02Multiple parties involved: property owner, neighbour, builder, council
- 03Original design drawings and engineering certification missing
- 04Insurance liability disputed between property owner and builder
Outcomes
- 01Root cause: design deficiency (no drainage, insufficient reinforcement, no toe key)
- 02Builder liability established through engineering analysis of design departures
- 03Expert report used in insurance subrogation proceedings
- 04Replacement wall designed with proper drainage, reinforcement, and founding