Discussion of and solutions for the large deformation mechanism of a tunnel in carbonaceous slate

The Muzhailing tunnel of the Lanzhou-Chongqing railway, which is built under the complicated geological conditions of weak surrounding rocks, such as high ground stress, carbonaceous slate, and so on, exhibits obvious large deformation and partial failure in the carbonaceous slate section. Aiming at the large deformation of the Muzhailing tunnel, the influence factors regarding the occurrence of large deformation in carbonaceous slate are analyzed in this paper. The large deformation mechanism is studied, including the plastic deformation of carbonaceous slate, bending of the plate-girder, shear slip, and damage to the pressure bar. Thus, the construction measures, such as the surrounding rock stress, the reinforced support, and the advance control, are adjusted in order to control the large deformation of a tunnel, and this experience provides a reference for future tunnel construction in carbonaceous slate. ©, 2014, Editorial Office of Modern Tunnelling Technology". All right reserved."