Previous studies have demonstrated that reducing earthquake-induced damage to central columns in underground structures can effectively prevent the collapse of overall structures. Truncated columns (TC) are less likely to experience severe damage during lateral deformation because the partial release of the constraints at both ends of the columns helps maintain their integrity. This approach can effectively enhance the seismic performance of the overall underground structures. In this study, pushover and shaking table tests were conducted to investigate the seismic performance of a subway station using TC columns compared to that using the cast-in-place columns (CC). These tests aimed to examine failure modes, structural stiffness, lateral deformation and load-bearing capacities, acceleration and deformation responses of the underground structures. The results from the pushover tests indicated that the initial stiffness of both structures-those with TC and with CC-was equivalent. On the other hand, the shaking table tests showed no significant differences in the dynamic responses of the two types of underground structures under small earthquakes. However, the vertical ground motions exacerbated damage to the structures. Although the lateral load-bearing capacity of the structure with TC is somewhat lower, the movements between the column ends and beams during loading enhance the structure's ability to adapt to the deformation of surrounding soil due to the release of column end constraints. As a result, the seismic resistance of the overall underground structures is improved. It is important to note that the ceiling slab and sidewalls in the structures with TC are more likely to crack during earthquakes, thus requiring additional efforts to prevent leakage. The findings of this study provide experimental evidence that supports the seismic control of underground structures.

The behavior of center columns in shallow-buried underground subway station structures resembles that of high-rise buildings. In both cases, these columns experience significant vertical loads during earthquake events and are susceptible to brittle failure due to inadequate deformation capacity. In this study, the design concept of split columns, commonly employed in high-rise structures, is adapted for application in a two-story, two-span subway station. Initially, a comparative analysis was conducted using quasi-static pushover analysis to assess the horizontal deformation characteristics of traditional and split columns under high axial loads. Subsequently, a comprehensive quasi-static pushover analysis model encompassing the soil-structure interaction was formulated. This model was employed to investigate differences in seismic performance between traditional and innovative underground structures, considering internal forces, deformation capacity, and plastic damage of crucial elements. The analysis results demonstrate that the incorporation of split columns in a two-story, two-span subway station enhances the overall seismic performance of the structure. This enhancement arises from the fact that split columns mitigate excessive shear forces while effectively utilizing their vertical support and horizontal deformation capacities.