软土地区桥台桩基负摩阻力试验研究

软弱土地基上的基桩,由于桩周土的向下运动,土与桩的摩擦增加了桩的下拉荷载,这就是所谓的桩侧负摩阻力,负摩阻力的存在增大了桩基的变形甚至导致破坏。通过软土地区桥台桩基的现场试验研究,获得了软土地区台背路基填土过程之中和之后的第一手资料,揭示了软土地区桥台路基填土时,桥台基桩内力和负摩阻力的变化规律。试验结果表明:台后填土对桥台基桩轴力的影响不仅发生在填筑施工期间,而且在施工完毕后相当长一段时间内仍有一定的影响;由于负摩阻力的作用,桩身轴力随着深度的增加先增大后减小,桩侧摩阻力沿深度呈非线性变化。

In-situ tests on negative friction resistance of abutment piles in soft soil

With regard to the pile foundation in soft soil, because of the downward movement of the soil around the piles, the friction between the soil and the piles increased the downdrag of the piles, and it was called the negative skin friction. The result is that it increases the deformation of piles and even leads to the destruction of pile foundation. The first-hand materials about the change of the axial force of pile is obtained during and after embankment fill behind abutment in soft ground by the field test of the piles, and it reveals the variation of the internal force of pile and the negative skin friction. Test results show that the influence of embankment fill on the axial force of piles exist not only during the construction, but also a long time after the construction. The axial force of piles first increases with the depth and then decreases. The variation of negative skin friction with the depth of piles is nonlinear.