基于试桩试验的桩侧注浆抗拔桩承载变形特性的荷载传递法

依托上海虹桥综合交通枢纽工程开展了4组桩侧注浆抗拔桩的现场试桩试验，得到了各试桩各土层的桩侧摩阻力与桩土相对位移关系曲线（?-w曲线）。首先，对前述现场试桩试验得到的?-w曲线以及文献1]中通过桩土接触面大型直剪试验得到的?-w曲线进行归一化处理，归一化参数为各土层极限侧摩阻力?ult及其相应的临界桩土相对位移wult；然后采用双曲线函数拟合归一化后的各土层?/?ult-w/wult曲线，得到一个统一的?/?ult-w/wult函数关系式；最后，将该双曲线函数应用到荷载传递法中，用于分析预测桩侧注浆抗拔桩的承载变形特性，可求得桩侧注浆抗拔桩桩身各处的荷载-位移曲线、桩身轴力分布曲线以及桩侧摩阻力分布曲线。通过工程案例的验证表明，其计算结果与工程案例实测值较接近，在上海地区具有一定的适用性。

A load transfer method for analyzing side-grouting uplift piles based on pile tests

Full-scale static load tests of four sets of uplift piles with side-grouted are carried out in the project of Shanghai Hongqiao Comprehensive Transportation Hub. Curves of side resistance and relative displacement relationship (?-w curve) of all soil layers in the pile range are derived based on the measured data. Firstly, make every soil layer τ-w curves of the full-scale test and the ?-w curves from the direct shear test normalized, in which the normalized parameters are the ultimate side resistance and the corresponding critical relative displacement of pile and soil. Secondary, a hyperbolic function is used to fit the normalized data; and then a unified ?/?ult-w/wult function curve is obtained. Finally, the unified fitted curve is applied into load-transfer method, and the pile head load-displacement relation, pile axial force and side friction distribution curve along the pile depth under different test load levels are gotten easily, so as to use it to predict bearing capacity and deformation properties. It is meaningful in the theoretical analysis and practical engineering.