上拔荷载下砼芯水泥土桩工作性状及破坏机理研究

    Working characteristics and failure mechanism of concrete-cored deep cement mixing (CDCM) piles under tensile load

    • 摘要: 近年来砼芯水泥土桩作为抗拔桩在地下水位较高的东部沿海软土地区中得到了广泛的应用,目前对上拔荷载下砼芯水泥土桩工作性状的研究较少。本文介绍了一组上拔荷载下砼芯水泥土桩的模型试验研究,随后通过数值模拟深入分析其破坏机理,并讨论了芯长比以及含芯率等因素对砼芯水泥土桩承载性能及破坏模式的影响规律。研究结果表明:砼芯桩身最大拉应力位于桩顶,拉应力随着深度逐渐减小,随着芯长比的增大水泥土桩桩身抗拔承载力逐渐提高;水泥土桩复合桩段桩身拉应力总体较小,但在砼芯底部附近存在应力突增,选择合适的含芯率能够降低桩身受拉破坏的风险,研究成果可为砼芯水泥土桩的设计及实际工程应用提供依据。

       

      Abstract: The concrete-cored deep cement mixing (CDCM) piles have been widely used as uplift piles in soft soil areas of Eastern China with high groundwater levels in recent years, while the research on the behavior of CDCM pile under uplift loads remains limited. This paper presents a group of model tests of CDCM pile under uplift loads to study its uplift bearing capacity. Subsequently, the numerical simulations are conducted to analyze the failure mechanism in detail. The influencing factors such as core length ratio and core pile content ratio on the bearing capacity and failure modes of CDCM pile are discussed based on the simulation results. The research results indicate that the maximum tensile stress in the CDCM pile occurred at the pile head, gradually decreasing with depth. The uplift capacity of CDCM pile increases with the increase of core length ratio. The overall tensile stress in the composite section of the cemented soil column is relatively low, while a stress surge occurs near the bottom of the concrete core. Adopting an appropriate core content rate can reduce the risk of tensile failure in the pile shaft. The research findings can provide a basis for the design and practical application of CDCM piles.

       

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