Influence of a new‐bored neighbouring cavity on the seismic response of an existing tunnel under incident P‐ and SV‐waves

• Published in: Earthquake engineering & structural dynamics Vol. 50; no. 11; pp. 2980 - 3014
• Main Authors: Zlatanović, Elefterija, Šešov, Vlatko, Lukić, Dragan Č., Bonić, Zoran
• Format: Journal Article
• Language: English
• Published: Bognor Regis Wiley Subscription Services, Inc 01.09.2021
• Subjects: Addition theorem; analytical solution; Boundary conditions; Cylindrical waves; dynamic stress alteration factor; Elastic waves; Hoop stress; incident P‐wave/SV‐wave; Mathematical analysis; P-waves; Seismic activity; Seismic propagation; Seismic response; Seismic wave propagation; Seismic waves; seismically safe distance; Stress propagation; Tunnel construction; Tunnels; tunnel–cavity system; Wave diffraction; Wave functions; Wave propagation
• ISSN: 0098-8847; 1096-9845
• DOI: 10.1002/eqe.3497

One of the important problems regarding the tunnel design in seismically active areas is the assessment of the mutual effect of two closely running tunnels. With the propagation of seismic waves, the stresses in certain sections of a tunnel, owing to the presence of an adjacent tunnel, can exceed those occurring when considering the single‐tunnel case. In the focus of this study is the hitherto unexplored elastic wave diffraction problem, which considers the influence of the presence of a new‐bored neighbouring cavity on the seismic response of an existing tunnel, under incident P‐waves/SV‐waves. The wave function expansion method, the corresponding boundary conditions along the tunnel and cavity contours, and the translational addition theorem for bi‐cylindrical wave functions are jointly employed to develop an exact mathematical solution of the given problem in the form of infinite FourierBessel series, under the plane‐strain conditions. The dynamic effects of structures are presented in the form of a newly introduced dynamic stress alteration factor as a measure of the variation of dynamic hoop stress amplitudes in the lining and the surrounding medium of an existing tunnel affected by the presence of a closely running newly‐constructed tunnel opening. The results of this study are believed to be useful for interpretation of design rules, particularly considering that seismic standards for tunnels are still in the preliminary stage, where the aspect of the minimum seismically safe distance of a newly‐constructed tunnel opening in the vicinity of an existing tunnel should be of particular concern.