Abstract
Long term earthquake observations at different tunnel sites within a variety of alluvial soil deposits have clearly demonstrated that a circular tunnel is liable to deform in such a way that its two diagonal diameters crossing each other expand and contract alternately. Based on this knowledge, the soil-tunnel interaction for this particular vibration mode is investigated. The soil surrounding a tunnel is assumed to be a homogeneous elastic medium, and two extreme boundary conditions on the soil-tunnel interface are considered; the condition of fixed tangential strain and the shear stress-free condition. The former case suggests a firm bond between the tunnel lining and the soil, whereas the latter case is associated with an artificial slippery soiltunnel interface.
