Following a heavy rainfall event in February 2022, the soil below the concrete pathway failed, leaving the
concrete pathway and house foundations (along rear edge of the house) undermined. DTCE have been
engaged to design the underpinning and retaining to support the concrete path and house foundations.

Due to the significant self-weight of the concrete pathway, a conventional retaining wall solution was not practical. Instead, DTCE developed a system of reinforced concrete columns to support the gravity and seismic loads of the pathway, while also acting as structural supports for the retaining wall lagging. The design considered soil-structure interaction, seismic loading in accordance with NZS 1170.5, and varying site geometry to ensure stability of the affected area.

The solution was developed to address the localised failure and ensure ongoing support of the pathway and foundations.