考虑颗粒形貌的砂土导电特性及模型研究

    Study on the Electrical Conductivity Characteristics and Modeling of Sand Considering Particle Morphology

    • 摘要: 岩土体电阻率受多种因素影响,其中与颗粒形貌参数相关的孔隙结构特征在电阻率结构参数表征中起关键作用。现有关于形貌参数对导电特性评价的研究多基于理想条件下的理论推导,存在形貌参数不全、作用机制认知不足、物理意义不明及参数难以测量等问题。本文以五种典型形貌砂土为对象,通过形貌参数测量和四电极电阻率测试,探讨二维颗粒形貌与电阻率参数的相关性,并从细观尺度分析其作用机制。研究表明,五种砂土的长宽比、凸度、圆度和球度等参数近似服从正态分布,其期望值可定量表征颗粒形貌;不同形貌砂土在归一化饱和度与孔隙率下的电阻率变化规律一致,电阻率随饱和度和孔隙率增大而减小,呈幂函数关系。相关电阻率结构参数与“平均形貌因子”Am亦具幂函数关联,在相同孔隙率和饱和度下,颗粒越浑圆,导电性越好,形貌通过影响孔隙水导电路径曲折度显著改变电阻率;且不同砂土的电阻率差异随饱和度和孔隙率增大而减弱,本文提出考虑颗粒形貌影响的电阻率修正模型,并与经典Archie及H-B模型对比验证,表现出更优的适用性与精度。该成果为砂土导电特性研究及电学测试在岩土工程中的应用提供了理论与数据支撑。

       

      Abstract: The electrical resistivity of geotechnical media is influenced by various factors, with pore structure characteristics related to particle morphology playing a key role in resistivity parameterization. Existing studies are mostly theoretical and based on idealized assumptions, often limited by incomplete morphological descriptors, unclear mechanisms, and measurement difficulties. This study investigates five types of sands with typical particle shapes. Using morphological analysis and four-electrode resistivity testing, the correlations between 2D morphological features and resistivity parameters were examined, alongside micro-scale mechanism analysis. Results show that aspect ratio, convexity, roundness, and sphericity approximately follow normal distributions, with expected values effectively representing particle shape. Under normalized saturation and porosity, all sands exhibit similar trends: resistivity decreases with increasing saturation and porosity, following a power-law relationship. Resistivity parameters also correlate with the average morphological factor (Am) via power functions. At the same porosity and saturation, higher particle roundness enhances conductivity by reducing the tortuosity of pore water paths. Moreover, resistivity differences among sands diminish as saturation and porosity increase. A morphology-informed correction model is proposed and validated against the Archie and H-B models, showing improved accuracy and applicability. The findings provide theoretical and experimental support for understanding sand conductivity and advancing resistivity-based methods in geotechnical engineering.

       

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