Abstract: The paper was aimed at exploring the adaptability of construction methods of the three-line super-large section tunnel in dolomite stratum of Chengdu-Kunming Railway. Based on the physical and mechanical tests of surrounding rocks, five construction methods of new dolomite tunnel were simulated by the FLAC^3D program. According to the time-space effect of the transverse and longitudinal deformation of surrounding rocks, the deformation response and adaptability of the super large section dolomite tunnel under various working conditions were analyzed. The results show that in order to better control the deformation of the tunnel cavity during tunnel excavation, the cross diaphragm (CRD) method should be preferred, followed by the double-wall guide pit method, that different construction methods have the greatest influence on the tunnel invert, that in the excavation process, the earlier the step is excavated, the later the deformation is affected by the disturbance, while the later the step is excavated, the more the pre-deformation is sensitive to disturbance, that by adding a temporary inverted arch and center diaphragm, the excavation section is divided into a plurality of closed excavation faces, which not only helps to control the deformation of the tunnel, but also has a good control effect on the extrusion deformation of the face, and that theoretical conclusions about the tunnel construction methods in dolomite stratum can provide guidance for deformation control of similar large cross-section tunnels of Sichuan Tibet railway.

Key words: super large section, tunnel engineering, construction method, laboratory test, numerical simulation, adaptability