超长嵌岩桩初始后屈曲性状分析

为探讨超长嵌岩桩初始后屈曲性状,先将桩身视为部分支撑的温克尔地基梁,提出基于组合桩侧土抗力模式建立桩土体系总势能方程。然后基于变分法导得临界荷载表达式,并应用扰动法和变分法推导得超长嵌岩桩初始后屈曲过程中临界荷载变化值与桩土体系参数的一般关系式。据此分析了不同参数对桩身屈曲及初始后屈曲平衡性状的影响。结果表明:初始后屈曲过程中的桩身平衡分枝点具有对称性,但稳定与否与桩侧土抗力模式、桩土刚度比及桩身埋置率等参数有关;设计规范的m法不能很好地反映超长桩的桩侧土抗力模式,所得的临界荷载值偏大。采用组合桩侧土抗力模式分析超长桩的屈曲及后屈曲较m法更为合理。

Initial post-buckling analysis for super-long rock-socketed piles

To investigate the initial-post buckling behaviors of super-long rock-socketed piles,a mechanical model simplifying the pile as partially supported Winkler foundation beam is adopted,and a combination model of soil resistance of the pile-soil system is applied to establish the potential energy equation.The expression of buckling critical load is derived by using the variational method.And then by using the perturbation method and the variational method,the general expression of the critical load change relative to different pile-soil system parameters in the initial-post buckling process is deducted,and effects of these parameters on the initial-post buckling behaviors of the piles are discussed.The results show that the initial-post buckling has balance path of the piles with symmetry branching points,and the balance of the pile-soil system relates to the soil resistance patterns,soil-pile stiffness ratio,the embedded proportion of pile shaft and other parameters of the system.The m method can not exactly reflect the real model of pile side soil resistance and a larger pile critical buckling load will be derived.So the combination model of soil resistance is more reasonable than the m method of soil-pile side resistance mode.