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张恩祥, 赵天时, 王正振, 戴国亮, 周勇, 龙照, 杨阳. 非达西流影响的超长桩荷载传递研究[J]. 岩土工程学报, 2022, 44(S1): 213-218. DOI: 10.11779/CJGE2022S1038
引用本文: 张恩祥, 赵天时, 王正振, 戴国亮, 周勇, 龙照, 杨阳. 非达西流影响的超长桩荷载传递研究[J]. 岩土工程学报, 2022, 44(S1): 213-218. DOI: 10.11779/CJGE2022S1038
ZHANG En-xiang, ZHAO Tian-shi, WANG Zheng-zhen, DAI Guo-liang, ZHOU Yong, LONG Zhao, YANG Yang. Load transfer of super-long piles considering influences of non-Darcy flow[J]. Chinese Journal of Geotechnical Engineering, 2022, 44(S1): 213-218. DOI: 10.11779/CJGE2022S1038
Citation: ZHANG En-xiang, ZHAO Tian-shi, WANG Zheng-zhen, DAI Guo-liang, ZHOU Yong, LONG Zhao, YANG Yang. Load transfer of super-long piles considering influences of non-Darcy flow[J]. Chinese Journal of Geotechnical Engineering, 2022, 44(S1): 213-218. DOI: 10.11779/CJGE2022S1038

非达西流影响的超长桩荷载传递研究

Load transfer of super-long piles considering influences of non-Darcy flow

  • 摘要: 为建立黄土地区超长桩的荷载传递计算方法,基于非达西流定律以及中心差分法推导出了在非达西流作用下的孔隙水压力计算公式,进而推导得出土体沉降量计算方法;然后以传统荷载传递法为基础,得出桩土相对位移计算模型,推导了大厚度黄土地区超长桩的下拉荷载理论计算方法;最后结合某桩基础试验,将计算结果与传统的达西定律推导出的结果以及试验结果进行对比。结果表明:①理论计算方法所得出的桩侧土体沉降与桩基侧摩阻力及轴力分布与试验结果吻合较好,能很好地反映出超长桩的荷载传递规律;②传统达西流计算得出的流速较大,导致孔隙水压力在未固结的某一时间点消散速度快于非达西流计算结果,这是达西流计算结果存在偏差的主要原因;③与非达西流动结果相比,传统达西定律推算得出的桩侧正摩阻力值偏小,未能充分发挥桩侧正摩阻力和桩基础承载力,造成较大浪费,故在计算桩侧阻力及分析桩周土变形规律时考虑非达西流影响十分必要。

     

    Abstract: In order to establish the load transfer method for the super-long piles in loess areas, based on the non-Darcy flow law and the central difference method, the formula for calculating pore water pressure under the action of non-Darcy flow is deduced, and the method for soil settlement is derived. Then, based on the traditional load transfer method, the model for the relative displacement of pile-soil is obtained, and the theoretical method for the pull-down loads on the super-long piles in thick loess areas is deduced. Finally, by combining with a pile foundation test, the calculated results are compared with those derived from the traditional Darcy's law and the test. The results show that: (1) The soil settlement at the pile side, side friction and axial force distribution of the pile calculated by the proposed theoretical method are in good agreement with the test results, and can well reflect the load transfer law of the super-long piles; (2) The velocity calculated by the traditional Darcy flow is large, which leads to that the dissipation speed of pore water pressure at a certain time point of unconsolidated flow is faster than that calculated by the non-Darcy flow, and this is why the calculated results by the Darcy flow are deviated. (3) Compared with that by the non-Darcy flow, the value of the normal friction at the pile side calculated according to the traditional Darcy law is small, which can not give full play to the positive frictional resistance of the pile side and the bearing capacity of the pile foundation, resulting in a great waste. Therefore, it is very necessary to consider the influences of non-Darcy flow when calculating the side resistance of the pile and analyzing the deformation law of soils around the pile.

     

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