Tunnel Shotcrete Linings - Recent Experiences from Design and Certification of Tunnels in Sydney, Australia
The paper presents a critical review and discussion of the design methodologies and technical standards applied for the design of tunnel shotcrete linings of several major recent underground infrastructure projects in Sydney, including both urban road and railway metro tunnels. By being involved in these multiple projects in either the role of the Designer or Independent Checker/Certifier, this review was made from a unique vantage point, allowing a comprehensive insight into the local industry practices and standards. The review focused on key parameters that are essential inputs for all empirical, analytical and numerical analysis of the tunnel shotcrete linings, discussing the challenges faced by Designers to comply with the specified structural standards and by Contractors to validate those key parameters through testing procedures during the construction stage. The paper outlines conclusions regarding design methods, structural standards, technical guidelines and provide recommendations to reduce misalignments between design, construction specifications and quality control to optimise the overall outcome of future projects.