Abstract:

In order to prevent collapse and control deformation of Luza inclined shaft of Muzhailing Tunnel on LanzhouChongqing Railway located in carbonaceous slate, the author analyzes the behavior and deformation mechanisms of the carbonaceous slate, as well as countermeasures to control the deformation. The conclusions drawn are as follows: the carbonaceous slate is a kind of soft ground subject to softening when water is encountered; collapse is subject to occurring after excavation in waterbearing sections, therefore advance reinforcement and pregrouting are needed; tunnels located in highstressed carbonaceous slate are subject to long convergence period and large deformation; countermeasures such as installing invert to form a closed ring, long rock bolts, radial grouting and protection arch can be taken to control the deformation.

Key words: carbonaceous slate, tunnel, key construction point, deformation control