Modeling and simulation of high-frequency vibration of headrace tunnel in a pumped storage power station considering imperfect bounding condition

High-frequency vibration (HFV) is a recently reported phenomenon in the headrace tunnel of pumped storage power stations (PSPS). These vibrations propagate through the upstream mountain, generating severe noise on the surface and disrupting the lives of local residents. In some cases, it may be necessary to relocate these residents, which increases the secondary costs associated with constructing PSPS. Therefore, modeling and predicting the vibration intensity of the headrace tunnel is crucial for the engineering design and stable operation of these facilities. In this study, a numerical model is developed to simulate the HFV response of the headrace tunnel, considering the interactions between the fluid, pipe, and surrounding rock. The interface between the pipe and surrounding rock is normally imperfectly bounded due to the existence of uneven surfaces, waterproof layers and interstices, and so on. The linear spring model is introduced to describe these imperfect characteristics. This study provides a strategy for determining the spring constants, which can be used to estimate the bonding degree between the pipe and the surrounding rock. The vibration response of the headrace tunnel is investigated based on the data from an actual PSPS, and the dominant vibration characteristics are analyzed.