The whole length of Lanzhou-Chongqing Railway is about 819 kilometers, which has long distance and great terrain fluctuation. To keep away from bad geological conditions from Minxian to Longnan, group tunnels were constructed.
Considering cost input and construction convenience, schedules were made and self drilling anchor was as the main supporting effect to control deformation. Self drilling anchor was arranged symmetrically and drill machines helped to drill holes. The distance between anchor bolts was 1 meter.
Before tunnel construction, analogous calculation and analysis were carried out, such as geological conditions, choice of parameters, digital simulation, supporting effect with ANSYS, stability of surrounding rocks, etc.
Then the steps of construction were as follow: drill holes, insert self drilling anchor bolt, grout slurry and lock steel arch.
During the construction of railway tunnel, self drilling anchor has reaction with surrounding rocks, which depended not only on terrain conditions, but also on self drilling anchor’s support effect.
In weak conditions, self drilling anchor has better reinforcement effect than common bolt. Self drilling anchor can change the mechanical property of surrounding rocks, enhance self-supporting capacity, reduce deformation of surrounding rocks and then keep tunnel’s stability.