Exploratory application of a novel centre cross diaphragm method for the construction of large cross-section tunnels in soft ground

Abstract

For tunnelling in urban areas, the current sequential excavation (SE) method usually increases the number of temporary drifts to achieve better control of surface settlements, which may prolong construction duration. In this case study, a four-drift SE method, termed the suspension-type centre cross diaphragm (S-CRD) method, was proposed and applied to the construction of a large cross-section tunnel in soft ground, where normally the six-drift double-side drift (DSD) method would be adopted. Field monitoring results and statistical data indicated that, in comparison with the six-drift DSD method, the four-drift S-CRD method achieved better control of the surface settlements while improving the efficiency of construction by 30%. The advantages of the S-CRD method, i.e., safe and rapid construction, were eminently clear.