MT KEIRA PASS

STABILISATIONWollongong City Council

MT KEIRA PASS WORKS

•About 500m of rockfall hazard reduction works

•180m of lower embankment anchoring and no fines concrete reconstruction

•Around 400m of asphalt and spray seal works

•2100m2 of stabilisation, using lime slag

MT KEIRA PASS STABILISATIONRockfalls and Embankment Slumping

PROBLEMS•Ongoing rockfalls, anytime but particularly during heavy rain and storms•Continuous slow creep of the road embankment due to fill weathering and settlement•Narrow carriageway with poor sight distance increasing the risk to the road user (drivers, walkers and cyclists)

MT KEIRA PASS STABILISATIONInvestigation

20 boreholes were drilled for the design of the embankment works. The pavement was logged and later used in the design of the pavement stabilisation.

Previous slump repairs consisted of repeated layers of deeplift asphalt, up to 650mm thick. Top of guardrail was lower than road crown prior to reconstruction.

Geotechnical inspection of cliff face above road for the design and markup of rockfall measures

Note slope of road (Landcruiser) compared to vertical drill rig – 14 degree camber, with radial tension cracking.

MT KEIRA PASS STABILISATIONConstruction

Upper rockfall hazard reduction works underway, showing meshing, bolting and elevated 38kJ catch fencing installation

Lower embankment works occurring concurrently, showing anchoring, meshing and concrete edge reconstruction.

Note additional carriageway width (from 5.5m to 7.5m)

MT KEIRA PASS STABILISATIONStabilisation Works

Premilling, crossblending and grading to shape – 300mm depth minimum. Grading and compaction of stabilised material into embankment edge.

Spreading 5% of 30:70 lime slag binder, water addition and remilling. Final shape was achieved by grading to produce a 2% crossfall to the inside drain and left 30mm low for later AC works.

Spray sealed 7/7/2014, getting ready for soft opening. AC scheduled for October.