城市桥梁基桩承载性能时间效应试验研究

岩土的流变性质使建（构）筑物基础的承载性能具有时间相关性，对运营期建筑结构的安全性造成较大的影响。为了进一步探讨城市桥梁桩基础承载性能随时间的变化规律，对某桥梁工程的2根试验桩进行了长效荷载试验研究，得出了桩顶沉降和桩身承载性能随时间的变化规律。利用桩基承载性能时空效应新理论对试验结果进行分析拟合，获得真实的桩土力学参数，得到工程桩桩顶沉降随时间变化的解析解。试验成果进一步揭示了桩在长效荷载作用下自然而真实的发展变化规律，为检验验证理论研究成果提供可靠的依据，可用于指导同等条件下工程桩设计和施工时预测桩的工后沉降变化趋势，控制基础稳定性，同时为解决路桥的工后运营期沉降控制提供科学合理的理论依据。

Experimental research on time effect of bearing performance of foundation piles for urban bridges

Pile’s bearing performance of building can be changed with time, because of the rheology of roch and soil. The time- dependent deformation of piles may affect the serviceability of piled structures after completion. This paper presents the results of a pile loading test under working load for a period up to 100 days. Two 800 mm-diameter bored piles with different pile lengths for bridge foundations were tested. The axial load distribution along the piles during loading was measured with stressometers attached to the reinforcements. The side friction resistance was obtained during each loading. The creep behavior and the settlement of the piles under serviceability limit states were revealed. The test results were analyzed using the new spatiotemporal effect theory of pile’s bearing performance. Analytical results were obtained with calibrated parameters. The results can be used for the design of pile foundation and to predict the long-term settlement of piles，and to solve the problem of controlling the differential settlements after bridge being completed.