THE PROJECT
A 30 m section of the Hyland Hwy collapsed following a landslide triggered by extremely heavy rain, resulting in a prolonged lane closure. After completing detailed geotechnical investigations and optioneering, a 7 m high anchored soldier-pile retaining wall was identified as the preferred remedial works solution designed for 100 years of service life. The remedial works were delivered under a Design & Construct contract by Fulton Hogan Industries.
PSM was engaged as the lead designer for the site remedial works. Our scope included:
- Development of a detailed geotechnical model and assessment of failure mechanisms
- Geotechnical design of piles, pavements and ground anchors
- Structural design of the retaining wall including ground anchors
- Construction-phase services including pile inspections and ground anchor testing
ENGINEERING AND TECHNICAL OPPORTUNITIES
Deeply weathered older volcanic soils with reduced strength due to fissuring within the clay soil.
Ground anchors founded within soils rather than rock.
Elevated, perched and varying groundwater conditions.
Working on top of an active landslide area.
Bespoke design requirements for ground anchor bearing assemblies
Construction undertaken adjacent to live traffic.
APPROACH AND INNOVATION
- 2D geotechnical finite element analysis utilising PLAXIS to analyse interactions between natural ground, landslide-disturbed material and the new retaining wall.
- 3D structural finite element analysis using Strand7 to assess load distribution and structural behaviour within the retaining wall.
- Developed a bespoke specification for ground anchor construction and testing in weathered soils.
- Provided active construction-phase support to verify complex ground conditions and design refinements to optimise project outcomes.
OUTCOMES
PSM collaborated closely with the contractor and client to deliver a robust design, enabling the successful construction of the remedial works and the safe reopening of the Hyland Highway to the public.
Services: #Civil #Geotechnical #Structures #Landslide #Geohazard #Highways
