Picture 1. Celebrating the Successful Threading in Site

On January 16，2021， the downstream of Headrace Tunnel 4# and the upstream of Headrace Tunnel 5# (CHMC Laos Nam Ngum 4 Hydropower Station Project),was successfully threaded together. The control distance between Headrace Tunnel 4# and Headrace Tunnel 5# is totally 3525 meters, which is the maximum control section since the start of the Project construction.

As for the complex geological conditions in this control section, CHMC Project Department of Laos Nam Ngum 4 Hydropower Station, adopted the method of alternate of 'Three-stage Excavation' and 'Full Section Excavation', adopted support measures such as steel arch frame and spray mixing to solve the deformation of surrounding rock effectively. At the same time, CHMC Project Department overcame the impact of the epidemic situation, constantly optimized and improved the construction process, grasped the implementation, caught up with the progress, ensured the safety construction of the Project as scheduled.

The successful threading of the Headrace Tunnel 4# and Headrace Tunnel 5#, laid a solid foundation for the whole threading of headrace tunnels in Laos Nam Ngum 4 Hydropower Station Project.