Abstract:

In this paper, a rapid construction technology based on flexible support, rockburst prediction, loose ring test and flexible net test is proposed for hard rockburst tunnel by analyzing selfstability and rockburst characteristics of hard rock tunnels. The rockburst strengths of rockburst section of Micangshan Tunnel under different buried depths are predicted by Tao Zhenyu criterion and Turchaninov criterion; rockburst strength sections are rationally divided; and the loose loop test and flexible net test are carried out to study and verify the parameters of anchor and the wirerope net. The practical results show that: (1) The rockburst prediction and rockburst strength section division can be carried out accurately by Tao Zhenyu criterion and Turchaninov criterion. (2) The loose loop test results can roughly determine the depth of the rupture area after excavation. (3) Compared to traditional support technology, by using rapid support technology of shotcreting + expansion and prestressed bolt + flexible protection net can save about 4 hours every cycle and increase the construction speed of rockburst section by 30% to 40%.

Key words: hard rock tunnel, rockburst prediction, loose loops, wirerope net, flexible support, rapid construction