Seismic displacement and deformation analyses of a precast horseshoe segmental tunnel

Abstract

This paper investigated the seismic response of a precast horseshoe segmental tunnel (PHST) by using 1-g shaking table tests, with a specific focus on the transversal deformation of the PHST model (tube). The structural responses of the tube, including the absolute and relative displacements in both the horizontal and vertical directions as well as the flexure at the segmental connections, were investigated in this study. The measured horizontal responses of the tube and the nearby soil were in phase. The dynamic response of the tube in the horizontal direction was strongly affected by the predominant frequency of the site and the frequency content of the earthquake motions. On the other hand, the vertical responses at the crown and the invert differed in terms of peak values and displacement direction, indicating that the tube vibration in the vertical direction was not governed by the soil. Furthermore, the tube experienced horizontal racking deformation as well as compressive-expansive deformation in both the horizontal and vertical directions, which slightly increased flexural bending at the connections. However, the peak of the most unfavorable deformation corresponded to the peak of the horizontal racking deformation. Therefore, the ratio of the horizontal racking deformation to the tunnel cross-section height is recommended as an important indicator of seismic performance.