Abstract:

The calculation of the cost of shield boring in soft strata is mature, however, there is no unified cost calculation basis for shield boring across hard rocks. In the paper, four hardrockcrossing shield tunneling methods, i.e., shield boring directly across the hard rock, blasting before shield boring across blasted hard rock, mining and primary supporting before shield advancing without load and segment erecting, and mining, primary supporting and secondary lining before shield advancing without load, are compared technically and economically. In the end, optimum solutions are proposed for specific conditions.

Key words: Metro, shieldbored tunnel, hard rock section, cost