超大直径嵌岩桩受力特性的数值模拟及其规律性分析

Numerical simulation and analysis of mechanical characteristics for large-diameter rock-socketed piles

贵州赫章特大桥主墩高195 m,由20根直径2.5 m、长40 m的嵌岩桩支撑。桥区范围内地质条件较为复杂,为了掌握此复杂地质条件下嵌岩桩受力特性、桩侧阻和端阻分布及其变化规律,建立嵌岩桩单桩和群桩的三维有限元分析模型,开展超大直径嵌岩桩单、群桩的分析和研究,获得了一些有价值的结论:对于覆盖层深厚的超大直径嵌岩桩基础,覆盖层分担一定比例的桩顶荷载,若在设计中忽略覆盖层的影响是不经济的;嵌岩桩侧阻与端阻的发挥并非同步,即侧阻先于端阻发挥;合理的嵌岩深度有利于调动整个嵌岩段的侧阻发挥和提高端阻和覆盖层侧阻荷载分担比。

The main pier of in Hezhang Bridge Guizhou province has a height of 195 m, which is supported by 20 rock-socketed piles with 2.5 m in diameter and 40 m in length. The engineering geological condition of the main pier site is very complex. In order to investigate its mechanical characteristics, end bearing and shaft resistance distribution, 3D finite element analyses for individual pile and pile group are carried out. Some valuable conclusions are drawn: the overlaying stratum shares a certain proportion of the upper load, so it is uneconomical to neglect its influence in design; the shaft resistance and tip resistance are not mobilized synchronously, the shaft resistance is mobilized prior to the tip resistance; the reasonable depth of rock-socketed piles can improve the shaft resistance and enhance the load sharing ratio of the tip resistance and the shaft resistance of the overlaying stratum.