Limit Analysis of Shear Failure in Concrete Slab–Wall Joints of Overlapped Subway Stations

In subway stations constructed using the cut-and-cover method, an increasing number of projects are adopting the form of precast components combined with on-site assembly. However, analysis of the novel structural elements within such overlapped subway stations remains inadequate. To simulate the shear failure mechanism at slab–wall joints, the structural behavior of these joints in overlapped subway stations is idealized as a rigid die stamping problem. An admissible failure mechanism is constructed, comprising a rigid wedge zone and a vertical tensile fracture perpendicular to a smooth base. The limit analysis approach is adopted, a two-dimensional velocity field is constructed, and the upper-bound theorem is applied to determine the bearing capacity of these joints under strip loading, utilizing a modified Coulomb yield criterion incorporating a small tensile stress cutoff. The failure mechanism proposed on the basis of an engineering case is validated through analytical calculations and parametric studies. Finally, a parametric analysis is conducted to investigate the influence of factors such as the geometric configuration of the slab–wall joints and the tensile and compressive strengths of concrete on their ultimate bearing capacity. The results obtained can provide an effective reference for the design and construction of precast slab–wall joints in future overlapped subway station projects.