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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。
Self-balance detection method effectively solves many problems that traditional static load method faces in pile foundation inspection and has been widely popularized and applied. Among them, the value of conversion coefficient γ is one of the key problems in the calculation of bearing capacity of self-balance method. Aiming at the situation of cohesive soil existing in the soil of bridge engineering in our country, and based on the project of Taizhou Bay Project, the value of the conversion coefficient in self-balance bearing capacity test method in cohesive soil was tested in situ. Three bored piles with a pile diameter of 1.5 m and a pile length of 83.5 m were selected. The self-balance method and the pile-loading method were successively used on the original pile, and the corresponding pile side frictional resistance , Comparing the limit side frictional resistance measured by self-balance method and the limit side frictional resistance measured by pile-loading method for the upper pile of each pile in the same soil layer, the self-balance conversion coefficient of each layer is obtained, Based on the collected data of two piles of similar projects, the results show that the ratio of the self-balance method of bored piles to the ultimate friction of upper pile measured by pile-loading method is 0.7-0.8.