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岩土工程数值模拟技术中参数选取的正确性是反应材料真实力学特性的基本前提。借助于颗粒离散元分析软件PFC2D,对黏性土类材料样本开展了大量的平面双轴压缩试验。通过记录不同围压下样本的轴向应力峰值,并依据摩尔-库仑强度准则对数值试样的剪切强度参数(内摩擦角、黏聚力)进行标定。着重探讨了黏性材料细观参数中颗粒刚度比kn/k(s0.5～10共12组)、颗粒粘结强度SBS(0～50 kPa共12组)、颗粒摩擦系数μ(0～6共16组)以及颗粒粘结强度比K(0.1～10共15组)和材料宏观剪切强度参数以及材料剪切特性之间的相关性。研究结果表明:颗粒粘结(法向、切向)强度同对材料黏聚力呈线性相关;颗粒摩擦系数与材料内摩擦角呈近似对数相关;颗粒刚度比大小对材料剪切强度参数变化亦有微弱的影响;此外,K值(切向粘结强度/法向粘结强度)是影响材料的剪切破坏形态的重要因素。最后,采用了两个多元非线性拟合公式,定量地描述了以上各细观参数和材料宏观剪切强度参数的联合关系,并给出了K值的建议取值,为后续的研究提供重要的理论基础。
The correctness of parameters selection in geotechnical numerical simulation is the basic prerequisite for the real mechanical properties of reactive materials. With the help of PFC2D software, a large amount of planar biaxial compression tests on clay samples were carried out. The axial stress peaks at different confining pressures were recorded, and the shear strength parameters (internal friction angle, cohesion) of the specimens were calibrated according to the Mohr Coulomb strength criterion. The micromechanical properties of viscous materials such as kn / k (s0.5 ~ 10 in total), adhesion strength of particles SBS (12 groups of 0 ~ 50 kPa), particle friction coefficient μ A total of 16 groups), as well as the correlation between particle cohesive strength ratio K (0.1 to 10 in total 15 groups) and material macroscopic shear strength parameters and material shear properties. The results show that there is a linear correlation between the bond strength (normal and tangential) and the cohesion of the material. The friction coefficient of the particles is approximately logarithmically related to the friction angle of the material. The variation of the shear strength parameters In addition, K (tangential bond strength / normal bond strength) is an important factor affecting the shear failure morphology of the material. Finally, two multivariate non-linear fitting formulas are adopted to quantitatively describe the joint relationship between the above mesoscopic parameters and the macroscopic shear strength parameters of the materials and give the suggested values of K values, which are important for the subsequent research The theoretical basis.