Cross Passages Ground Treatment for Melbourne Metro Tunnel Project-PPT Presentation

PPT Presentation

Pdf Summary

The Melbourne Metro Cross Passages Ground Treatment project treated five cross-passage locations between January 2019 and December 2020. Jet-grouted columns were installed around the passages, typically at depths of 18–26 metres and at an inclination of 35 degrees. The ground included sands, gravels, silts, fill and mudstone.<br /><br />The treatment was designed to extend 2 metres around each passage and meet a five-year design life. Key performance requirements included a minimum 28-day unconfined compressive strength (UCS) of 1.5 MPa, permeability no greater than 1 × 10⁻⁷ m/s, and Young’s modulus of at least 225 MPa.<br /><br />Work was complicated by active railways, low headroom, nearby utilities and overhead high-voltage lines. Production quality assurance combined the Cyljet system, drilling-deviation and diameter measurements, grout testing, installation records, and 3D as-built modelling. Primary, secondary and tertiary columns were adjusted or supplemented where deviation measurements indicated potential gaps. Core recovery, UCS, stiffness and permeability tests assessed the treatment’s continuity and material properties.<br /><br />Cross-passage excavation used remote-controlled demolition robots. Exposed columns were mapped and compared with the 3D as-built models. Monitoring recorded up to 2 mm of ground heave during column installation at CP03. Before segment lining was opened, probing and pressure grouting met the specified performance criteria without additional injections.<br /><br />The project team credits the successful delivery to new technology, real-time monitoring, digital as-built records, responsive design review and coordination among the subcontractor, designer and main contractor. The project was completed on time and within budget.

Keywords

Melbourne Metro

cross passages

jet grouting

ground treatment

Cyljet system

unconfined compressive strength

permeability

3D as-built modelling

remote-controlled demolition robots

railway infrastructure