Simplified Calculation of Earthquake Energy Transfer of Different Pipe Supports Inside Utility Tunnel at Horizontal Non-Homogeneous Field

A buried utility tunnel can effectively protect internal pipes by preventing or mitigating corrosion, external damage, and facilitating maintenance. During an earthquake, the energy from seismic waves is transmitted through the soil to the utility tunnel, then to the support structure, and ultimately to the pipe, making the support’s interaction with the pipe crucial. In this study, scaled utility tunnel system undergoes shaking table tests at a horizontally non-homogeneous site. Various supports within the tunnel are modeled dynamic elements to assess energy dissipation. The attenuated seismic waves are then applied directly to the pipe to evaluate its response and validate the results against the tests. The study reveals that greater sliding between the tunnel and pipe leads to more energy dissipation and reduces the likelihood of significant pipe deformation. Situations with increased sliding of the side-wall angle steel support exhibit smaller strain peaks. Longitudinal sliding becomes more pronounced only when peak ground acceleration exceeds 0.8 g in longitudinal loading. The transverse sliding response under longitudinal loading is not influenced by the input acceleration peak. Additionally, modeling the internal pipe's interaction with the support as a simplified dynamic element yields more accurate responses, offering a foundational calculation for the design of shock absorption and vibration isolation in utility tunnel supports.