基于实测动刚度的桥桩承载能力评估研究

提出了适用于批量评估分析的、基于实测动刚度的桥桩承载能力评估方法。结合某公路特大桥大批量桥墩基础评估加固工程，利用瞬态机械阻抗法对680根桥桩进行动测。通过基桩低应变完整性辅助测试及动刚度统计分析，推算了桥桩承载能力并给出加固建议。研究表明，对于桩身完整的桥桩，动刚度与承载能力在统计上具有明显的正相关关系；对于承受相近设计荷载的桥桩，测桩样本较大时动刚度值对桥桩完整性评估具有较好可信度。通过抽样取芯分析，验证了提出的桥桩承载能力评估方法具备较好的可靠性。

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.