ABSTRACT
In view of the complicated process and low work efficiency of the traditional excavation method of the super large section four-lane tunnel, based on the project of the reconstruction and expansion of the large section four-lane deep Shanxi tunnel, the reconstruction and expansion construction method of the CRD of the super large section four-lane tunnel is studied by combining numerical simulation and theoretical analysis, and on this basis, the mechanical characteristics of the reconstruction and expansion construction of the CRD are further studied for the CRD construction method. The results show that the CRD method is applicable to the IV. and V. surrounding rock highway tunnels of the oversized four-lane tunnel; when the CRD method is used for the shallow buried surrounding rock of the V. class, the recommended upper step height is 3/5B tunnel height; before the demolition of the next door, the settlement of the left and right guide pit vaults in the tunnel excavation process is first increased, and then basically unchanged; when the next door is demolished, the sedimentation volume suddenly increases, and then the second lining is applied, and the settlement basically no longer changes. The research results can provide reference and reference for the reconstruction and expansion of the super-large cross-section tunnel.
