A novel technique for constructing prefabricated subway stations under open excavation

Prefabricated construction is essential for realising green, efficient and sustainable development of rail transit. However, limited space in foundation pits and cross-interference with inner struts mean that the advantages of existing prefabrication technology cannot be leveraged effectively to build subway stations under open excavation with inner support. In this paper, this problem is addressed by introducing a modular design method and two novel connection technologies. The proposed modular design method is sufficiently adaptable to balance the use of space between the station structure and the inner struts. The two proposed connection technologies provide efficient ways to assemble different concrete segments with two newly developed joints – namely, a CHC joint (comprising two C-shaped and one H-shaped steel members) and a flexible lock joint – in the circumferential and longitudinal directions, respectively. The first application of this fully prefabricated scheme in the Shenzhen Metro shows the huge potential of this technology for constructing subway stations under open-cut conditions, and its advantages in technical, economic and social aspects reveal wide application prospects in rail transit.