Evaluation of seismic mechanical response of tunnel linings using shaking table tests and numerical analyses: Fid-Bau Portal

Evaluation of seismic mechanical response of tunnel linings using shaking table tests and numerical analyses

Baziar, Mohammad Hassan / Dehghani, Roohollah

Abstracts This paper investigates seismically induced circumferential forces and bending moment of tunnel linings using a series of large shaking table tests and numerical analyses. In this regard, a scaled-down tunnel, embedded in two different depths of sandy soil, was tested under different frequencies of input motion. Then, dynamic finite difference analyses, first verified using the results of the performed large scale shaking table tests, were conducted to study the effects of depth ratio (h/a; h: depth of tunnel centerline and a = radius of the tunnel), flexibility ratio (1.2, 10 and 110) and different frequencies of input motion, corresponding to the dimensionless periods (λ/D), on the mechanical behavior of the tunnel lining. The results indicated that, low frequencies of input motions for the tunnel with low flexibility ratio resulted in greater circumferential bending moment values of the tunnel lining. Furthermore, the tunnel depth and adjacent surface foundation intensified the bending moment, shear, and axial forces of the shallow tunnel by about 43 and 17% and did not affect the maximum bending moment and forces locations in the tunnel lining. It is, therefore, necessary to consider the effect of a surface foundation on tunnel lining when constructing shallow subway tunnels in urban areas.

Highlights • Shaking table tests and numerical analyses are used to study dynamic tunnel response. • Effect of the tunnel flexibility ratio on the tunnel lining forces is investigated. • Effect of tunnel depth and input motion frequency on the tunnel lining forces is studied. • Presence of ground foundation on the dynamic stress of the tunnel lining is examined.