考虑双重孔隙结构的钙质砂CPT贯入离散元模拟研究 English Version
A Discrete Element Modeling Study on CPT Penetration of Calcareous Sand Considering Dual Porosity Structure
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摘要: 本文提出了一种考虑双重孔隙结构，并能够生成定量内孔隙的钙质砂颗粒离散元数值模拟方法。该方法针对钙质砂相较于石英砂的三大重要特征：丰富的双重孔隙结构、显著的颗粒形状长宽比、以及易破碎特性，开展了静力触探CPT贯入模拟研究，分析了CPT贯入钙质砂过程中双孔隙和颗粒形状因素对锥尖阻力、侧摩阻力和力链传递的影响。研究结果表明，内孔隙是影响颗粒整体强度的主要因素，而外孔隙则对颗粒间接触强度有显著影响。随着钙质砂内外孔隙的增大，CPT贯入过程中锥尖阻力和侧摩阻力的最大值相应减小，同时贯入曲线的稳定区域范围增大，力链传递的演化效果受到抑制。此外，颗粒形状的长宽比对钙质砂的堆积方式有显著影响，也会对CPT贯入结果造成影响。钙质砂颗粒的易破碎性是其显著特征，研究表明内孔隙对颗粒破碎起着重要作用。本文研究为钙质砂的原位测试提供了有效的参考。Abstract: This paper introduces a discrete element numerical simulation method for calcareous sand particles that incorporates dual porosity structures. The method focuses on three key characteristics of calcareous sand in comparison to quartz sand: abundant dual porosity structure, pronounced particle aspect ratio, and susceptibility to breakage. The study involves CPT penetration simulations to analyze the effects on cone tip resistance, side friction, force chain transmission, and displacement fields during penetration. The findings indicate that internal porosity is the primary factor influencing the overall strength of the particles, while external porosity significantly affects the contact strength between particles. As the internal and external porosity of calcareous sand increases, the maximum values of cone tip resistance and side friction during CPT penetration decrease accordingly. Simultaneously, the stable region of the penetration curve expands, and the evolution of force chains and displacement fields is suppressed. Moreover, the aspect ratio of particle shape has a significant impact on the packing behavior of calcareous sand and also influences CPT penetration outcomes. The susceptibility of calcareous sand particles to breakage is a notable characteristic, with internal porosity playing a crucial role in particle breakage. The proposed model offers valuable insights for in-situ testing of calcareous sand.
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Keywords:
- calcareous sand /
- internal porosity /
- aspect ratio /
- CPT /
- DEM /
- particle breakage
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