Abstract The No. 3 tunnel on Nanya Road in Guiyang is a twin-tube independent single-span four-lane munici? pal tunnel with the maximum excavation span of 21.878 m and the maximum excavation area of 245.7 m2 as well as developed underground karst and joint fissure since it is located in karst area, the , and the rock mass is fractured and construction time is tight. A research on the construction optimization of single-span four-lane municipal tunnel in weak and fractured surrounding rocks is conducted based on the construction period target. The strength reduction method is used to quantitatively evaluate the surrounding rock stability of the unsupported cavern and it is found that the unsupported rock of grade IV has the conditions to reach self-stability but the unsupported rock mass of grade V doesn′t meet the requirement of safety factor; based on the construction simulation and construction period deduction of different construction methods, the construction scheme is optimized, and it is determined for theNo. 3 tunnel at Nanya Road to adopt three-bench five-step excavation method in the surrounding rock of grade Ⅳand double side drift method for the rock mass of grade V; the switch of construction method for the main tunnel in rocks of grade Ⅳ and Ⅴ is optimized, and the construction period is shortened by 9 months.
Abstract：
The No. 3 tunnel on Nanya Road in Guiyang is a twin-tube independent single-span four-lane munici? pal tunnel with the maximum excavation span of 21.878 m and the maximum excavation area of 245.7 m2 as well as developed underground karst and joint fissure since it is located in karst area, the , and the rock mass is fractured and construction time is tight. A research on the construction optimization of single-span four-lane municipal tunnel in weak and fractured surrounding rocks is conducted based on the construction period target. The strength reduction method is used to quantitatively evaluate the surrounding rock stability of the unsupported cavern and it is found that the unsupported rock of grade IV has the conditions to reach self-stability but the unsupported rock mass of grade V doesn′t meet the requirement of safety factor; based on the construction simulation and construction period deduction of different construction methods, the construction scheme is optimized, and it is determined for theNo. 3 tunnel at Nanya Road to adopt three-bench five-step excavation method in the surrounding rock of grade Ⅳand double side drift method for the rock mass of grade V; the switch of construction method for the main tunnel in rocks of grade Ⅳ and Ⅴ is optimized, and the construction period is shortened by 9 months.
YANG Zhiqiang1 FANG Jing2 LIU Xianglin1 ZHENG Yuchao2
.Research on Construction Optimization of Single-span Four-lane Municipal Tunnel Based on Construction Period Target[J] MODERN TUNNELLING TECHNOLOGY, 2020,V57(2): 184-191
2020, Vol. 57 