Limberg II breakthrough

摘要

The Wirth gripper TBM driving the 3.9km inclined headrace for the Limberg II hydro project, in Austria, has holed through on schedule.The 7.03m diameter open TBM was refurbished and overhauled for the contract, which required it to bore through basalt and gneiss at a 45° (degree) incline. The rock was of average UCS 100MPa but was locally higher, reaching 150MPa. Much of the length of the tunnel was unlined, having a minimum excavated diameter of 7m, but shotcrete was used in parts.