不同荷载作用下桥梁摩擦桩承载特性研究

研究桥梁钻孔灌注摩擦桩的承载特性及桩身力学性质的分布规律对桥梁的安全稳定运行具有重要意义。以重庆三店互通式1号桥梁桩基为研究对象，根据桥梁桩基特点设计室内试验，依次进行了灌注摩擦桩单桩承载力、桩身轴力以及侧摩阻力等桩基性能研究，并将试验结果与数值模拟结果以及理论公式计算结果进行对比验证。研究表明：持力层岩性对桥梁灌注摩擦桩桩顶沉降量存在影响，持力层岩土性能越高，则桩顶沉降量越小；桩身轴力及摩阻力的变化幅度均随着桩顶荷载的增加呈先增大后减小的规律，且桩身中部所受到的摩阻力最大；经理论公式和有限元分析的验证，本次试验结果整体上偏差率较小，3种分析计算方法均可较好地得出灌注摩擦桩桩身轴力变化规律。研究结果可为桥梁运营后期的病害防治提供重要的理论支撑。

Bearing characteristics of bridge friction piles under different loads

It is of great significance to study the bearing characteristics of cast-in-place friction piles constructed by drilling grouting technique and the distribution law of the pile mechanical properties for the safety and stability of bridge operation. Taking the pile foundation of Chongqing Sandian Interchange Type 1 Bridge as the research object, the laboratory test was designed according to the characteristics of the bridge pile foundation, and the performance of the single pile bearing capacity, pile axial force and side friction resistance was studied successively. Then the test results were compared with those of the numerical simulation and theoretical formula. The results show that the lithology of the bearing layer affects the top displacement of the bridge pile, the higher the geotechnical performance of the bearing layer, the smaller the displacement amplitude of the pile top. In addition, the variation range of the pile axial force and friction resistance increases first and then decreases with the increase of the pile top load, and the friction resistance is the largest in the middle of the pile. According to the verification of the theoretical formula and finite element analysis, the overall deviation rate of the laboratory test is small, it reflects that the variation law of the pile axial force are well expressed under these three calculation methods. The findings can provide an important theoretical support for the prevention and control of damages to bridges in the later period of operation.