Mila Mountain Tunnel is located in Tibet, China. It is about 5.7 kilometers long and 21.5 meters wide. It belongs to the first-class highway with bi-directional and four-lanes. Speed is predicted 80 kilometers per hour. The pavement of whole line is bituminous concrete. And this project plans to be opened to traffic in September, 2017.
It is introduced that Mila Mountain Tunnel is the highest highway tunnel in the world. The left hole, right hole and inclined shaft of this tunnel are IV.V-class surrounding rock, it has high request on construction quality. So the process is complex and difficulty is quite clear.
Facing with so many difficulties, supporting operation of self drilling anchor bolt has played an important role on the safety of construction.
There are several problems need to be considered during the construction:
1. Before installing self drilling anchor bolt, there are loose rocks falling down when cleaning. So workers have trouble in operating anchoring under this area.
2.When working on muck bank or frame, safety should be noticed.
3.Workers should cooperate with each other. Temporary supporting shouldn’t be canceled before linking steel frame with self drilling anchor bolt.
4.When deformation or crack appears during the process of drilling and grouting, efficient remedial measures should be adopted according to the rock conditions and workers should get rid of danger areas.
5.When filling grout into self drilling anchor bolt, pressure gauge should be checked closely. If the indication is too high, special measures should be applied and ignoring blocking. In addition, nozzle of grouting pipe should not point to people.
6.Workers should operate according to the operation procedure strictly, ignoring the occurrence of security accident.