TRANSPOWER TUNNEL STRENGTHENING
Project Value $1.2 Million
Description : The existing reinforced concrete cable tunnel that is located under the Botany shopping centre was cracking and showing signs of potential failure. March Cato submitted a design and build proposal to Transpower to strengthen the tunnel using steel liner segments, winched into place and grouted.
Work undertaken included:
• Construction of two deep sheet piled launching shafts.
• Confined space tunnelling and robust health and safety systems were required.
• The liners had to be winched up to 200m and sealed against the adjoining liner. This was further complicated by curvature in the tunnel.
• A special grout mix was designed to achieve the required strength while maintaining the appropriate viscosity for pumping.