Analytical solution of Tunnel-Soil-Tunnel (TST) interaction under seismic excitation

This research proposes the analytical formulations for the vertically aligned twin tunnels under the sinusoidal form of seismic excitation in the case of the damped free vibration. The analytical formulae are derived to calculate the interactive tunnel moment, tunnel shear force and soil pressure for the transverse horizontal shear (SH), vertical shear (SV) and body (P) waves. For the derivation of the analytical formulations, the twin tunnels are assumed as beam elements connected by the linear elastic springs. The tunnel-soil-tunnel (TST) interaction model is verified by the previous analytical solution and numerical analysis of the case studies. The ranges of the difference in results between the present research and the previous analytical solution are found to be (3.8 similar to 8.1) %, (6.73 similar to 10.95) % and (2.3 similar to 11.79) % in the case of the SH, SV and P waves, respectively. These differences may represent good agreement about verifications.