Study of bearing capacity evaluation for bridge piles by measured dynamic stiffness

Bearing capacity evaluation is important for existing bridge piles with potential defections. As the pile loading tests and high strain tests are not allowed to perform for some bridges in service, a bearing capacity evaluation method for bridge piles is proposed. This method is based on the measured dynamic stiffness of piles and can be used for evaluating large quantities of piles, according to the following three steps: pre-analysis, general investigation measurement and verification. Combined with a practical engineering that evaluation of a great many piles for a long highway bridge, dynamic measurement for 680 bridge piles are performed by impulse transient response method. Detail statistics for dynamic stiffness of the bridge piles is performed. Combined with the assistant low strain dynamic measurements, the pile bearing capacities are calculated; and reinforcement suggestions for piles are proposed. Finally, in order to validate the estimation method, 80 pile samples are selected to perform the core drilling analysis. Results show that: for integrated piles, the obvious positive correlation can be found between dynamic stiffness and bearing capacity of piles; moreover, the values of dynamic stiffness have good reliability for evaluating the bearing capacity of large number of piles when they bear the similar design loads. By analyzing drilling core samples, it is proved that the evaluation method proposed has good reliability. ©, 2015, Academia Sinica. All right reserved.