Abstract:

The application of rapid excavation technology in the construction of deep superlong hard rock tunnels can achieve shorter construction period and thus can result in good economic efficiency. Selecting proper blasting cyclic length, which can minimize the damage to the surrounding rock, is a prerequisite for rapid excavation. In the paper, the broken zone thickness and the deformation of the surrounding rock of Hongtiguan tunnel under 3, 35, 4, 5 m blasting cyclic lengths is evaluated by means of numerical simulation. Theoretical blasting cyclic length is obtained and applied in the tunneling. Finally, rational blasting cyclic length, i.e., 35~4 m in Grade Ⅱ surrounding rock, is proposed on basis of theoretical study and engineering practice.

Key words: deep superlong hard rock tunnel, rapid excavation, blasting, appropriate cyclic length, numerical simulation