Investigation of tunnel-ground interaction at weak zone during seismic loading: a research using 2D shaking table apparatus and corresponding numerical analysis

Weak areas adjacent to tunnel linings may emerge during or post-construction due to various factors, including substandard quality, water erosion, and dynamic loading. This research visually scrutinized the seismic response of the lining and the surrounding ground by employing a two-dimensional (2D) shaking table apparatus and assessing the influence of weak zones on tunnel integrity. The experimental setup used aluminium rods to replicate sandy ground conditions, and the weak zone was modelled by increasing the void ratio of the ground. The strain of the tunnel lining and the displacement of the surrounding ground were analyzed throughout the shaking process. Experimental findings revealed significant variations in ground movement and notable fluctuations in lining deformation, with observed quantities heavily reliant on the location of the weak zone. The volumetric strain variation indicates the lining can not observe enough reaction from the backside ground when weak zones exist, resulting in a heightened bending moment on the lining at this weak area. These observations underscore the potential for even minor weak zones to induce substantial damage to tunnel linings during seismic events. This paper presents the findings of the 2D shaking table test alongside corresponding numerical analyses, elucidating the dynamics of tunnel-ground interaction in the presence of weak zones during seismic loading.