A Study on the Dynamic Behavior of a Vertical Tunnel Shaft Embedded in Liquefiable Ground during Earthquakes

Abstract

Since liquefaction was first observed in South Korea during the Pohang earthquake, public concerns regarding the seismic stability of major infrastructure have increased substantially. However, the seismic behavior of tunnel shafts, which are an important element of tunnel structures, has not been properly established, especially under liquefiable soil conditions. In this study, 3D numerical modeling with Fast Lagrangian Analysis of Continua in 3 Dimensions (FLAC3D) was performed to predict the dynamic behavior of a vertical tunnel shaft during liquefaction. This study demonstrates key aspects of the dynamic behavior of tunnel shafts by varying important parameters such as the thickness of the liquefiable soil layer and applied seismicity level. Moreover, important dynamic responses such as excess pore pressure generation, the seismic bending moment of the shaft, and lateral displacements are highlighted. Finally, meaningful discussion of the seismic risk analysis based on damage indices is conducted based on the analysis results.

Design Study of Steel Fibre Reinforced Concrete Shaft Lining for Swelling Ground in Toronto, Canada

“…The Fast Lagrangian Analysis of Continua (FLAC) 2D, two-dimensional continuum explicit finite element analysis code developed by Itasca consulting group Inc., was used. This software has been widely used for geotechnical analysis application in the fields of civil mining engineering [56][57][58].…”