滩涂地区预压作用下人工硬壳层对桥梁桩基的影响分析： 以浙江省十一塘高速为例

滩涂地区深厚的软土地质条件给现浇箱梁的施工带来了较大挑战，依托浙江省十一塘高速公路一期工程，研究了预压荷载作用下人工就地固化硬壳层对桥梁桩基的影响。基于土体硬化模型建立了三维数值计算模型，对比不同硬壳层深度下桩身轴力、侧摩阻力和水平位移的变化规律，结果发现：当硬壳层厚度为2 m时，桩身轴力减少约16%且硬壳层的厚度会改变负摩阻力的传递深度，表现为硬壳层厚度越厚桩侧阻力中性点越往上移。此外，在一定深度影响范围内，硬壳层能够有效控制桩顶和不同深度处桩身水平位移，硬壳层厚度越大，桩顶水平位移越小。最后通过分析土体模量对桩身水平位移的影响发现，桩身水平位移会随该层土压缩模量的增大而减小且Eur的影响将高于E50及Eoed的影响。

Analysis of Influence of Artificial Hard Shell Layer on Bridge Pile Foundation under Preloading in Beach Area

Based on the existing deep soft soil geological conditions in beach area, greater challenges are brought to the construction of cast-in-place box girders. Relying on the first phase project of Shiyitang Expressway in Zhejiang Province, the influence of artificially solidified hard shell layer on bridge pile foundation under preloading load was studied. Based on the soil hardening model, a three-dimensional numerical calculation model was established. The variation law of axial force, lateral friction resistance and horizontal displacement of pile body under different depth of hard shell was compared. It can be concluded that when the thickness of the hard shell is 2 m, the axial force of the pile is reduced by about 16%. The thickness of the hard shell layer will change the transfer depth of the negative friction resistance, which shows that the thicker the thickness of the hard shell layer, the more the neutral point of the pile side resistance moves up. In addition, in a certain depth influence range, the hard shell layer can effectively control the horizontal displacement of the pile top and the pile body at different depths. The larger the thickness of the hard shell layer, the smaller the horizontal displacement of the pile top. Finally, the influence of soil modulus on the horizontal displacement of the pile is analyzed. It is found that the horizontal displacement of the pile will decrease with the increase of the compression modulus of the soil, and the influence of Eur is higher than that of E50 and Eoed.