Abstract The middle parallel pilot tunnel of the Yuelongmen Tunnel on the Chengdu-Lanzhou Railway encoun? tered severe deformation in the deep-buried mountain ridge section. After effective support measures were taken,the deformation tended to be stabilized. After excavation and breakthrough of the left line main tunnel in the corresponding deformation section of the pilot tunnel, severe deformation occurred again in the pilot tunnel and the left line main tunnel. On this basis, this paper systematically introduces the geological environment of the tunnel site area,regional geostress condition, deformation characteristics of surrounding rock during construction, and the process of identifying large deformation in site construction. The analysis shows that the large deformation in this section is caused by the weak and broken rock mass in the high geostress environment. In this special geological environment,the tunnel group effect is significant, and the large deformation is closely related to the included angle between the rock strata strike and the tunnel axis, and the included angle between the maximum horizontal principal stress direc? tion of the geostress and the tunnel axis. The problem of large deformation is solved by backfilling the middle pilot tunnel, constructing a new outside pilot tunnel with a larger spacing between pilot tunnel and main tunnel.
Abstract：
The middle parallel pilot tunnel of the Yuelongmen Tunnel on the Chengdu-Lanzhou Railway encoun? tered severe deformation in the deep-buried mountain ridge section. After effective support measures were taken,the deformation tended to be stabilized. After excavation and breakthrough of the left line main tunnel in the corresponding deformation section of the pilot tunnel, severe deformation occurred again in the pilot tunnel and the left line main tunnel. On this basis, this paper systematically introduces the geological environment of the tunnel site area,regional geostress condition, deformation characteristics of surrounding rock during construction, and the process of identifying large deformation in site construction. The analysis shows that the large deformation in this section is caused by the weak and broken rock mass in the high geostress environment. In this special geological environment,the tunnel group effect is significant, and the large deformation is closely related to the included angle between the rock strata strike and the tunnel axis, and the included angle between the maximum horizontal principal stress direc? tion of the geostress and the tunnel axis. The problem of large deformation is solved by backfilling the middle pilot tunnel, constructing a new outside pilot tunnel with a larger spacing between pilot tunnel and main tunnel.
TAO Yujing1 YUAN Chuanbao1 WANG Maojing1 SONG Zhang1 LIU Guoqiang2
.Analysis on Causes of Large Deformation in the Deep-buried Mountain Ridge Section of Yuelongmen Tunnel on Chengdu-Lanzhou Railway[J] MODERN TUNNELLING TECHNOLOGY, 2023,V60(4): 229-236
2023, Vol. 60 