CLIENT: BHP Billiton
DESCRIPTION Tunnel Strengthening
Specialist Site Services was contracted to stabilise and strengthen a 100 metre long safety egress tunnel in the Hunter Valley, New South Wales. The damaged infrastructure had reduced coal production by 30% costing the client valuable export dollars.
The tunnel required temporary propping with steel sets to ensure the safety of our project team during construction. All tunnel services were removed and water pumps installed to manage the in-bye end of the work area.
All reinforcing mesh was drilled and dowelled in and around the propped areas before the staged application of fibrecrete commenced. A steel pump line was installed to get fibrecrete to the work area and remove as required. Fibrecrete was placed manually with a thickness of 400mm required to meet the design specification. A final smoothing coat of shotcrete was applied over the fibrecrete to complete the repair work.
The design specification and testing criteria projected acceptable tunnel deflection measurements on completion. Our work continues to remain well within the allowable design tolerances. The tunnel strengthening project was completed ahead of schedule including zero LTI’s. The client has returned to full production with the knowledge that their critical infrastructure is secure