The M5 motorway tunnel: an education in Quality Assurance for fibre reinforced shotcrete

摘要

The underground extension of the M5 Motorway through the southern suburbs of Sydney, Australia, resulted in a two-lane dual carriage way of 3.8 km length under sensitive urban areas. Fibre Reinforced Shotcrete (FRS) was used in combination with permanent rock bolts to support the roof of these tunnels. The specified design life of 100 years for the major support elements required Quality Assurance (QA) measures that were extra-ordinary in their frequency and breadth. Persistent problems in achieving post-crack load carrying specifications using beams led to the adoption of Round Determinate panels as the basis for performance assessment. However, correlations in performance between the beams and panels had to be established, and obstacles to effective specimen production, handling, and testing overcome, before this test could be fully implemented as the basis for performance assessment.