目前数字图像匹配(digital image correlation, DIC)技术在岩土工程领域中的应用越来越广泛. 在室内模型试验中采用 DIC 分析技术可实现对沉桩过程中桩周土体位移的测量, 进而对桩周土体位移分布规律进行研究. 但是位于桩-土界面处的薄层土厚度较小, 其位移无法利用 DIC 技术进行测量, 因此对 DIC 分析技术进行改进, 可记录并计算桩-土界面土体位移场情况, 从而研究沉桩过程中压桩速度和桩端深度对桩-土界面土体位移的影响规律. 研究结果表明, 桩体贯入时桩-土界面土体位移的规律可分为初始阶段和稳定阶段, 初始阶段土体位移表现为急剧增大然后迅速减小, 而稳定阶段土体位移在 0 mm 附近波动. 总体来说, 在砂土中压桩, 桩-土界面土体随桩体贯入发生的位移较小. 在同一桩端深度处, 压桩速度越快, 桩-土界面土体位移越大; 当压桩速度相同时, 桩体贯入深度越深, 桩-土界面土体累计位移越大, 稳定阶段反弹位移越小. 研究结果对进一步揭示桩-土相互作用机理和桩-土界面受力变形机理具有一定的参考价值.

Recently, application of the digital image correlation (DIC) technique in geotechnical engineering is used widely. In model tests, the DIC technique can be used to measure soil displacement around a pile during pile penetration. However, measuring displacement on soil-pile interface is difficult since the disturbed soil layer in these areas is very thin. In this study, the DIC technique is used to measure soil displacement on the soil-pile interface. Combined with model tests, a modified DIC technique can produce interfacial soil displacements being subjected to the influence of penetration rate and depth. Analyses on the test results show that development of interfacial soil displacements from the start of pile penetration can be classified into two stages—initial stage and stabilization stage. In the initial stage, interfacial displacements sharply increases until 0.2 mm due to pile penetration followed by a quick decrease, while interfacial displacements tended to vary around 0 mm in the stabilization stage. At the same penetration depth, interfacial soil displacements increase with the pile penetration rate. Meanwhile, with the increase of pile penetration depth, the accumulated interfacial displacements increase, and soil rebound in the stabilization stage decrease. The findings in this study can shed some light into the study on the mechanisms of soil-pile interface behaviors.