Simplified analysis of seismic in-plane stresses in composite and jointed tunnel linings

This paper presents an analytical procedure for evaluating in-plane moments and thrusts in composite and jointed tunnel linings during earthquakes. The analytical procedure treats the tunnel lining as an inner jointed thin-walled shell coupled with an outer thick-walled cylinder embedded in linear elastic soil or rock. The outer thick-walled cylinder can also be used to approximately model a degraded zone around the tunnel lining caused by mechanical disturbance and/or disturbance of the in situ stress field due to tunnel construction. The influence of in-plane shear stress is taken into account by assuming the free-field ground response produced during an earthquake is perpendicular to the longitudinal axis of the tunnel. Solutions for moment and thrust are presented for cases involving slip and no slip at the liner–ground interface. A parametric study is performed to investigate the effects of joint flexibility and a degraded annulus of soil or rock around the lining on the seismically induced moments and thrusts.