| 黏性土中钻孔灌注桩自平衡转换系数取值研究 |
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| 引用本文： | 李小娟,陈雪奖,戴国亮,龚维明.黏性土中钻孔灌注桩自平衡转换系数取值研究[J].岩土力学,2016,37(Z1):226-232. |
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| 作者姓名： | 李小娟 陈雪奖 戴国亮 龚维明 |
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| 作者单位： | 1. 东南大学 土木工程学院，江苏 南京 210096；2. 台州市沿海高速公路工程建设指挥部，浙江 台州 318000 |
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| 基金项目： | 国家重点基础研究发展计划973项目（No.2013CB036304）。 |
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| 摘 要： | 自平衡检测法在桩基检测中有效解决了传统静载法面临的许多问题，已得到广泛地推广和运用，其中自平衡法承载力计算中转换系数γ的取值是关键性问题之一。针对我国桥梁工程地基土质普遍存在黏性土的情况，依托台州湾项目工程，对黏性土中自平衡承载力测试法中的转换系数的取值进行了原位试验研究。选取3根钻孔灌注桩，桩径为1.5 m、桩长83.5 m，在原桩上先后进行自平衡法和堆载法试验，在桩身土层交界处布设钢筋计得到相应的桩侧摩阻力，将每根桩的上段桩在同一土层处自平衡法测的极限侧摩阻力值与堆载法测的极限侧摩阻力值进行对比，得到了各层土自平衡转换系数值，在该基础上收集了相似工程2根桩检测数据进行分析，结果表明在黏性土中钻孔灌注桩自平衡法与堆载法测得的上段桩极限摩阻力之比为0.7～0.8。
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| 关 键 词： | 钻孔灌注桩 自平衡试验 堆载试验 转换系数 |
| 收稿时间： | 2015-04-09 |
Research on conversion coefficient of cast-in-situ pile in clay in self-balanced loading test |
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| LI Xiao-juan,CHEN Xue-jiang,DAI Guo-liang,GONG Wei-ming.Research on conversion coefficient of cast-in-situ pile in clay in self-balanced loading test[J].Rock and Soil Mechanics,2016,37(Z1):226-232. |
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| Authors: | LI Xiao-juan CHEN Xue-jiang DAI Guo-liang GONG Wei-ming |
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| Institution: | 1. School of Civil Engineering, Southeast University, Nanjing, Jiangsu 210096, China;
2. The Coastal Highway Construction Headquarters of Taizhou City, Taizhou, Zhejiang 318000, China |
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| Abstract: | Self-balanced loading test (also called O-cell test) has been widely used in the testing of pile foundation with the benefits of solving many difficult problems not to be resolved by the static load test. Determining the value of conversion coefficient (the ratio of downward shaft resistance to the upward shaft resistance) is crucial issue to the calculation of bearing capacity. On the other hand, because the universal existence of clay soil in China, the study of conversion coefficient in clayed area is required. Thus, based on the project of Taizhou bay bridge, the value of conversion coefficient of self-balanced loading test is studied by field tests. Three cast-in-situ piles, 1.5 m in diameter and 83.5 m in length in clay soil are loaded by self-balanced loading method firstly, and then by kentledge loading method. In order to eliminate the effect between these tests, kentledge loading test was carried out 4 month after self-balanced loading test. At each soil layers, strain gauges are installed in each pile to obtain the value of shaft resistance. The value of shaft resistance of each layer from self-balanced loading test will be compared with one from kentledge loading test. The values of conversion coefficient are obtained. Also, the compared results from the other two similar projects are collected. From above researches, the ratio of downward shaft resistance and the upward one in Taizhou bay bridge is rational ranged from 0.7 to 0.8; and the ratio from other two different projects also proved this result. |
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| Keywords: | cast-in-situ pile self-balanced loading test kentledge loading test conversion coefficient |
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