How will the Savio tunnel be excavated?
Construction of the 14-kilometre Savio railway tunnel will take place from both ends and through four access tunnels. Blasting will proceed in stages and the work cycle will take about 17-48 hours depending on the site. Tunneling begins with surveying. This is followed by investigation to determine the nature of the rock. If investigation shows that the rock is quite fractured, pre-grouting takes place. Holes 18 metres long are drilled into the rock and a cement solution is hydraulically pumped into these. This reinforces the surrounding rock. Next holes are drilled into the rock and charges are set. These are exploded and the tunnel is ventilated. Excavated rock is transported to the harbour site. The next stage of work is called scaling. This is performed by hand or mechanically and involves removing loose rock from the ceiling and walls of the tunnel. The tunnel may also need to be reinforced. This is accomplished with bolting and concrete injection. While excavated rock is being lo
