Project Overview:
Following heavy rain events during the 2013 wet season, a section of Kin Kin Road between chainages 35874 and 36027 showed signs of slope destabilisation. The steep terrain, narrow road width, and risk of further collapse made traditional stabilisation methods unfeasible. PCA Ground Engineering was engaged to deliver a customised solution that minimised road closures while ensuring long-term slope stability.
Challenges
- Steep adjacent slopes restricting machinery access
- Narrow road allowing no space for large piling rigs
- Risk of road closure disrupting local access
- Active tension cracks forming along the road alignment
- Need to limit surcharge and manage construction-stage stability
Innovative Solution
PCA designed and constructed a micropile A-frame structure to address the deep-seated slip zone. Key elements of the solution included:
- Excavation of the outer road lane to reduce load and create a lower working platform
- Installation of temporary soil nails in the excavation cut face
- Construction of a cantilevered concrete wall atop a micropile capping beam
- Dual-purpose design integrating geotechnical (A-frame) and structural (wall) performance
- Use of finite element analysis calibrated with structural models to predict deflection
- Long-term monitoring via two inclinometers embedded through the wall
Outcome
- Innovative hybrid solution met both geotechnical and structural requirements
- Successful slope stabilisation without full road closure
- Structure withstood multiple significant rainfall events with no measurable deflection
- Awarded in 2014 for engineering innovation on a complex site
