SH-wave-induced dynamic interaction of dense tunnel groups in a quarter-space

An analytical model is developed to study SH-wave scattering by densely grouped circular tunnels in an elastic quarter-space. Combining the method of images with wave function expansions, this approach solves the multiple scattering problem while satisfying stress-free boundary conditions at both horizontal and vertical surfaces. The analysis reveals how wave number, incidence angle, lining stiffness, and thickness collectively govern dynamic stress concentration patterns. Results show that wave coupling between adjacent tunnels and reflections from the vertical boundary significantly amplify local stresses. The proposed methodology offers a reliable foundation for assessing seismic performance and optimizing the design of underground tunnel networks in quarter-space geometries.