Ellerslie Abutment Upgrade

The existing western abutment of the Main Highway Overbridge required seismic upgrade with the use of seismic ground anchors in conjunction new reinforced concrete wall elements.

Prior to production works taking place, cored investigation holes were required to verify the type and nature of the basalt rock. DCN Drilling was engaged by Grouting Services and 3 cored holes were put down during the Christmas 2014 and New Year's 2015 Block of Line.

The next stage of works will involve the installation and testing of a pair of 200T proving trial ground anchors to verify the geotechnical ultimate bond rupture. This will be followed by the permanent anchoring production works which is scheduled to start late January 2015. Two rows of anchors will be installed through the existing abutment and tied off into new reinforced concrete beams. Starter holes will be cored through the existing abutment to provide a leader for the overburden casing system required to drill the holes. The upper row of anchors comprise pre-grouted 32mm diameter high-grade stress bar and the lower row of anchors comprise pre-grouted 32mm diameter low-grade threadbar. Lengths range from 8-15m and testing is required for verification.