Abstract:

The geological conditions of the entrance portal section of Laoyeling tunnel on Changchun～Huichun highway is extremely complex, where there exist fault zones and Quaternary clinosol that contains loesses, crushed stones, thick cumulose soil and rich water. Furthermore, the side slopes of the entrance portal section of the tunnel are high and the selfsupport ability of the ground of the side slopes and front slope of the tunnel is very poor. Therefore, it is of great importance to commence the tunnel excavation as soon as possible. The article presents in detail the measures taken so as to commence the excavation of the shallowburied entrance portal section of the tunnel in soft ground.

Key words: shallowburied tunnel in soft ground  , rapid construction of portal section  , construction technology