竖向激振下缺陷桩测管内水压响应解析解

    Analytical Solution for Hydrodynamic Pressure Response in Tubes of Defective Piles Under Vertical Excitation

    • 摘要: 桩身单孔管波法可以通过竖向激振作用下桩身声测管内孔压响应规律评估桩基完整性,但目前针对这一新型基桩无损检测技术的理论研究仍十分有限。因此,本文拟建立大直径缺陷桩-成层土耦合振动模型,在Laplace域内求解得到桩身内任意一点处径向应力解析解。结合Biot流体位移势函数,进一步推导得到测管内孔压时-深响应表达式。将所提出理论模型与已有解析解结果进行对比验证,同时将计算得到的水压响应波列图与现场实测数据进行比对,进一步证明了模型的有效性与合理性。基于验证后的解析解开展参数分析,探讨桩身缺陷程度、缺陷段埋深及桩周土体夹层等因素对测管内斯通利波传播特征的影响。结果表明,在桩身缺陷段埋深处的波列图呈现异常“K”字型波动特征,桩周土夹层对缺陷桩水压响应时深规律几乎没有影响。本文研究结论为单孔管波法工程实践提供理论支持,有助于该技术的进一步推广应用。

       

      Abstract: The tube seismic method evaluates pile integrity by analyzing the hydrodynamic pressure response in acoustic tubes embedded within piles under vertical excitation. However, theoretical research on this novel nondestructive testing technique for pile foundations remains limited. To address this gap, this study establishes a coupled vibration model for a large-diameter defective pile embedded in stratified soil. Analytical solutions for radial stress at any point within the pile in the Laplace domain are derived. By incorporating Biot's governing equations for fluid displacement potential, the time-depth hydrodynamic pressure response in the measurement tube is further formulated. The proposed theoretical model is validated through comparisons with existing analytical solutions. Additionally, the calculated hydrodynamic pressure wave patterns are compared with field-measured data, confirming the model's validity and rationality. Based on the validated analytical solution, a parametric analysis is conducted to investigate the effects of defect severity, burial depth of the defective section, and the presence of soil interlayers around the pile on the propagation characteristics of the Stoneley wave. The results reveal that abnormal K-shaped reflection signatures appear in wave patterns at depths corresponding to pile defects. Notably, soil interlayers exhibit negligible effects on the time-depth characteristics of hydrodynamic pressure responses in defective piles. The conclusions of this study not only provide theoretical support for the engineering application of the tube seismic method but also advance its standardized implementation in pile integrity test.

       

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