CLIENT: Roads and Maritime Services (RMS)
DESCRIPTION Slip Repair
During February 2013, heavy rain caused major landslips at Mount Seaview and further west along the Oxley Highway in New South Wales. Three downslope failures occurred, severely damaging the Oxley Highway and reducing the highway to a single lane.
The highway slip repair and stabilisation project consisted of 10m shear piles socketed into extremely hard rock including concrete capping beams, 10m ground anchors, 8m soil nails, subsoil drainage, scour protection, shotcrete, guard rails and pavement drainage.
Piling was carried out in very unstable ground with the highway remaining open at all times. This required a staged piling program of constructing a number of piles, allowing those piles to cure before safely progressing forward on stabilised ground. The pile design included a 2m socket in extremely hard rock requiring the use of a 450mm DHH to productively penetrate to depth. All sockets were then vacuumed clean before pile reinforcement and concrete was placed.
The slips further west required the construction of false formwork and no fines concrete to return the width of the highway to two lanes. Soil nails, mesh and subsoil drainage was then placed according to RMS specifications. SSS then installed guard rails and pavement drainage to manage future weather events including scour protection at the base of each repaired slip using a long reach excavator.