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刘俊伟, 张忠苗, 张乾青, 谢志专. 软黏土与粉土互层中开口预应力混凝土管桩性状研究[J]. 岩土工程学报, 2011, 33(3): 448.
引用本文: 刘俊伟, 张忠苗, 张乾青, 谢志专. 软黏土与粉土互层中开口预应力混凝土管桩性状研究[J]. 岩土工程学报, 2011, 33(3): 448.
LIU Jun-wei, ZHANG Zhong-miao, ZHANG Qian-qing, XIE Zhi-zhuan. Open-ended prestressed concrete pipe-piles jacked into soft clay interbeded with silt[J]. Chinese Journal of Geotechnical Engineering, 2011, 33(3): 448.
Citation: LIU Jun-wei, ZHANG Zhong-miao, ZHANG Qian-qing, XIE Zhi-zhuan. Open-ended prestressed concrete pipe-piles jacked into soft clay interbeded with silt[J]. Chinese Journal of Geotechnical Engineering, 2011, 33(3): 448.

软黏土与粉土互层中开口预应力混凝土管桩性状研究

Open-ended prestressed concrete pipe-piles jacked into soft clay interbeded with silt

  • 摘要: 对软黏土与粉土互层中静压预应力混凝土管桩的相关性状进行了现场试验研究。试验结果显示,桩周土体中不同深度处的超孔隙水压力在沉桩过程中呈现不同的变化规律。回归分析得出两个不同深度处的对数表达式,用以描述最大超孔隙水压力与初始竖向有效应力的比值随距离参数的变化规律。测斜试验结果说明,群桩施工过程中土体最大水平位移发生在渗透性相对较差的淤泥质黏土层中。单桩沉桩过程中,地面的隆起量随沉桩深度不断增加,但主要的隆起量发生在桩体位于浅层时。贯入过程中,开口管桩的管壁端阻与静力触探锥尖阻力显示出极为相似的变化规律,且两者之间的比值不随贯入深度和土塞高度的变化而改变。上硬下软的土层分布易形成闭塞现象,而上软下硬的情况则易导致土塞的滑动。分析认为开口管桩直径越大管壁越薄,形成的土塞高度则越大。

     

    Abstract: The shortage of comprehensive research data to better understand the behavior of the jacked open-ended prestressed concrete pipe piles in soft clay interbeded with silt prompts an experiment program, in which a series of in-situ tests are conducted. Different developments of pore pressure are caused in the vicinity of the piles at different depths during pile installation. Two logarithmic correlations are confirmed to effectively express the function of the normalized peak excess pore pressure to the distance parameter. The maximum outward horizontal soil movement occurs in soft mucky clay layer with poor permeability. The vertical displacement around one pile decreases with the increasing distance, and a majority of the movement occurs during the shallow penetration. The pile annulus resistance and CPT cone tip resistance have similar development during penetration, and this relationship is independent on penetration depth and incremental filling ratio of soil plug. An open-ended pile is prone to performance in a plugged mode as penetrating into a weaker layer, whereas transition to an unplug-mode is observed on reaching an underlying harder layer. A larger diameter with a relative thinner wall for an open-ended pile leads to a higher plug length.

     

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