Analysis of Ultimate Bearing Capacity of High Concrete Arch Dam with Cracks in Service Using Natural Vibration Frequency

Many high arch dams are in service with cracks, which degraded the integrity and ultimate bearing capacity of arch dam. In this paper, based on natural vibration frequency, the possibility for monitoring the ultimate bearing capacity of cracking arch dam in service was discussed theoretically using finite element numerical analysis. The effect of typical crack on the ultimate bearing capacity of arch dam was analyzed with hydro-pressure over-loading method. The relationship between the overload factor and natural vibration frequency of arch dam under different crack condition was studied. The calculation result shows the natural frequency variation caused by load-induced structure crack is obvious in hour scale. So it is feasible to assess the ultimate bearing capacity of cracking arch dam in service based on natural frequency monitoring. The natural frequency of arch dam measurements would be carried out by ambient excitation such as water discharge, operation of hydropower station and small earthquake.