黏性粗粒土颗粒宏细观力学参数相关性研究

Research on the Relationship between Mesoscopic and Macroscopic Mechanical Parameters of Cohesive Coarse Grained Soil

研究目的:为准确选取颗粒的细观参数以真实反映颗粒材料的宏观力学性质,利用量纲分析理论,得到黏性粗粒土数值模型的细观参数和宏观力学参数之间的相似关系。采用颗粒流软件,对黏性粗粒土材料样本开展大量的平面双轴压缩试验,并结合摩尔-库伦破坏准则,着重探讨黏性粗粒土细观参数中颗粒接触刚度系数比、颗粒摩擦系数以及颗粒接触黏结强度比与材料宏观强度参数的相关性,可为今后粗粒土颗粒材料力学参数的确定提供借鉴。研究结论:(1)颗粒接触刚度系数比与黏聚力呈明显的对数相关,与材料内摩擦角近似呈线性相关;颗粒摩擦系数对黏聚力有微弱影响并呈多项式相关,而对内摩擦角影响较大且呈对数相关;颗粒接触黏结强度对黏聚力影响显著,而对内摩擦角几乎无影响;(2)颗粒接触黏结强度比是影响材料剪切破坏形态的重要因素,宏细观力学参数会随着剪切破坏的形态不同而呈不同的相关关系;(3)该研究成果对快速、合理地确定PFC模型细观参数具有指导意义。

Research purposes： In order to select accurately particle mesoscopic parameters to reflect macroscopic mechanical properties of granular materials, scaling law that describes relationship between micro and macro parameters of cohesive coarse grained soils is obtained by using dimensional analysis. A number of plane biaxial compression simulation tests are carried out for cohesive coarse grained soil, and based on Mohr - Coulomb failure criterion, the relationship is interpreted between particle mesoscopic parameters of cohesive materials, including particle stiffness ratio, particle friction coefficient, particle contact bond strength ratio, and material macroscopic shear strength parameters, which can provide references for deteImining mechanics parameters of coarse grained soil particle material in the future. Research conclusions： （ 1 ） The relationship between particle stiffness ratio and cohesion force is obvious logarithmic correlation, particle stiffness ratio and internal friction angle meet linear correlation. Particles friction coefficient has a weak effect on cohesion force, and there is a polynomial relationship between them. While particles friction coefficient has a greater influence on internal friction angle and there is logarithmic correlation between them. Contact bond strength is significantly influence on cohesion force, but almost no impact on internal friction angle. （2）Particle contact bond strength ratio is the important factors to affect material shear failure form, the micro and macro mechanics parameters have different correlation under different shear failure form. （3） The study results have directive meaning to quickly and reasonably determine the micro - parameters of PFC model.