On March 18th, the right tunnel at the Yanjiazhai Tunnel outlet of the TJSG-3 section of the Yunnan Yongshan Connecting Line project successfully holed through, marking a new stage of comprehensive advancement for the project’s construction production.
The Yanjiazhai Tunnel outlet is located in Zhaotong City, Yunnan Province, facing the Jinsha River. The tunnel is designed as a separated twin-tube tunnel, with the right tunnel being 7,575.4 meters long and the left tunnel 7,542.8 meters long, making it the longest tunnel on the entire line with a maximum overburden of 933.26 meters. The surrounding rock mass mainly consists of moderately weathered limestone, shale, siltstone, and basalt. At the tunnel outlet, the overburden is shallow, with the surrounding rock classified as Class V, mainly consisting of silty clay, resulting in poor geological conditions, high water abundance in the rock mass, and significant construction difficulties.
Currently, the project’s construction camp, laboratory, batching plant, rebar processing plant, and other facilities have all been successfully put into operation, marking a new stage for the project’s production work.