Energy-Based Seismic Damage Assessment of Tunnels during the February 6, 2023, Kahramanmaraş Earthquake Sequence in Turkey

Abstract The February 6, 2023, Kahramanmaraş earthquake sequence (M7.7, M6.6, and M7.6) produced unprecedented ground-motion energy levels and caused extensive damage to both surface and subsurface infrastructure across southern Turkey. This study conducts a comprehensive, energy-based seismic damage assessment of masonry and RC tunnels affected by this earthquake sequence. A detailed postevent damage inventory was established through extensive field surveys and photographic documentation, capturing predominant failure mechanisms. For the selected tunnel structures, the nearest strong-motion records were analyzed to derive both conventional and energy-based intensity measures. The derived parameters—including acceleration time histories, Arias intensity, two-dimensional particle motions, spectral displacement (Sd) to spectral acceleration (Sa) demand spectra, linear and nonlinear acceleration and energy spectra, energy history diagrams covering input, damping, strain, and plastic, kinetic, and absorbed energy components—were evaluated individually to assess their contributions to the seismic response of the tunnels. The results indicate that energy-based parameters show a more consistent agreement with the observed damage severity of the affected tunnel structures, suggesting their potential usefulness for evaluating seismic performance of underground structures.