南京夹江大桥主塔基桩承载性状分析

 应用南京夹江大桥主塔两根试桩的大吨位静载荷试验成果，采用ANSYS有限元计算，对超长大直径嵌岩桩的承载性状进行分析，包括桩顶沉降、桩端阻和桩侧阻的分配与发挥，并对最佳嵌岩深度进行讨论。结果表明，超长大直径嵌岩桩一般为端承摩擦桩，桩端阻力不容忽视，当桩处于极限时，上覆土层的侧阻力已经发挥至极限，而嵌岩段阻力仍有一定潜力可挖。利用ANSYS模拟后发现，嵌岩段的侧阻力非线性特征明显，且呈现“两头大，中间小”的特征。同时，通过对不同嵌岩深度的研究，认为仅通过增加嵌岩深度来控制桩顶沉降作用不明显，软岩地区的嵌岩桩嵌岩深度可不必拘泥于规范所限的不大于5D。最后根据静载试验和有限元分析结果，对原设计提出了修改建议。

BEARING BEHAVIOR OF KINGTOWER FOUNDATION PILE OF JIAJIANG BRIDGE IN NANJING

Based on the data of static load test and results of ANSYS analysis，the bearing behavior of large-diameter and extra-long rock-socketed piles are studied. The settlement，the optimized rock socket depth，the distribution of side friction resistance and end resistance are mainly discussed. The results indicate (1) large-diameter and extra-long rock-socketed piles are generally end load friction piles，however，their end resistances cannot be neglected yet；(2) in the socketed section，the distribution of side friction resistance has obvious nonlinear characteristics，which are small at middle and big at both ends；(3) it is not effective to control pile head settlement only by increasing socket depth，and the rock socket depth can not be limited to the norms，which is less than five times of pile diameter. Therefore，some proposals are given to the design of piles.