摘要
The methodology of predicting pile shaft skin ultimate friction has been studied in a systematic way. In the light of that, the analysis of the pile shaft resistance for bored and cast in situ piles in cohesive soils was carried out thoroughly in the basis of field performance data of 10 fully instrumented large diameter bored piles (LDBPs) used as the bridge foundation. The undrained strength index μ in term of cohesive soils was brought forward in allusion to the cohesive soils in the consistence plastic state, and can effectively combine the friction angle and the cohesion of cohesive soils in undrained condition. And that the classical ' α method' was modified much in effect to predict the pile shaft skin friction of LDBPs in cohesive soils. Furthermore, the approach of standard penetration test (SPT) N value used to estimate the pile shaft skin ultimate friction was analyzed, and the calculating formulae were established for LDBPs in clay and silt clay respectively.
根据 10根试桩静载荷试验和桩身应力测试结果 ,在对桩侧极限摩阻力预测技术系统分析的基础上 ,研究了粘性土中LDBPs桩侧极限摩阻力的预测方法和指标确定 .针对硬塑状态的粘性土 ,提出了不排水强度指数 μ的概念 ,综合了粘性土不排水条件下内摩擦角和粘聚力 .基于这一概念 ,对传统的“α法”进行了扩展 ,使之更加有效地应用于粘性土中LDBPs桩侧摩阻力的预测 .同时还对SPT锤击数N预测粘性土中LDBPs的桩侧摩阻力进行了统计分析 。
