Abstract
This paper proposes an analytical method for the seismic design of circular shield tunnels in the cross section based on the seismic shear deformation. Since the seismic deformation of underground structures is primarily the shear deformation in terms of the whole cross section, the seismic deformation of the circular shield tunnels is close to the elliptical shape. The study shows that the shear strain ratio of the shield tunnels to free field ground is the hyperbolic function of the shear stiffness ratio between the ground and the shield tunnels. The seismic shear deformation of the shield tunnels is estimated by both the shear strain transmitting characteristics and the push-over analysis of the 2-ring frame model that can evaluate the effects of the transverse and circumferential segment joints.
