Incremental computing of supporting excavation with cover-cut

Underground construction in soft ground must be delicately tackled and a safe supporting system is crucial during deep excavation. Although conventional supported excavation (bottom-up or top-down method) does not occupy as much land as the open-cut method, the construction of a metro station under the city arteries still disrupts the transportation for some time (usually 24–36 months). The cover-cut method is defined in this paper, and recent metro station construction experience of the cover-cut method is presented. A comparison of the widely used summation and the ‘step-by-step’ approaches has been made. The latter method can take into account both the changing loads and the characteristics of the structure to calculate the stresses and deformations from the construction period to the application period. The results calculated by the step-by-step approach are seen to be more accurate than the conventional method.