Project introduction: the project site consists of alpine, valley and glacier suffering much from strong denudation and glacial erosion, featured by deep mountain, gully development and slope terrain. Mt. Gangri Gabu is the highest mountain in Motuo and on the boundary between Motuo and Bomi, with average peak elevation at more than 4,500m; the parts above 4,000m are shaped by glaciers with obvious point peaks and knife-edge crests; the parts in 3,500m to 4,000m is defined as the glacier movement area, suffering from strong glacial erosion, with the possibility of glacier avalanche and snow avalanche. The tunnel is in cold area and mountains contain more water. The tunnel structure encounters many severe tests. 

At two points, 700m at the entrance section and 500m at the exit section, FL FLOLIC FOAM Freezing-thawing Resistant System for Tunnels in Extremely Cold Areas is adopted for secondary lining finishing for freezing-resistance treatment; FLOLIC FOAM insulating thickness: 50 mm.