基于离散元的冻结砂土三轴力学特性研究

采用离散元软件中的平行黏结模型模拟冻土中冰-土颗粒间相互作用。通过调整模型细观参数，模拟了特定围压不同试验温度和应变速率条件下冻结砂土的三轴试验规律。进一步对比分析计算和试验结果表明，模型的细观参数中的刚度系数和黏结强度对材料的宏观力学行为影响较大，设定的黏结强度参数与温度成反比而和应变速率成正比。在宏观上，峰值强度随温度降低而增大，随应变速率的增大而增大。进一步分析离散元中颗粒的运动产生的剪切带倾角表明：剪切带倾角与温度成反比，而应变速率对其的影响较小；根据已有数据结果，剪切带与内摩擦角间的统计关系符合经典土力学中的摩尔-库伦解。

Study on triaxial mechanical behaviors of frozen sand based on discrete element method

In this paper, a parallel bond model embed in the PFC software was employed to simulate the interaction between ice and soil particles of frozen soils. Through adjusting the mesoscopic parameters of the parallel bond model, the mechanical behaviors of frozen sand under different temperatures and axial strain rates were analyzed. Based on the analysis of the calculated and tested results, it was indicated that two of the parameters in the parallel model (stiffness coefficient and bond strength) have a great influence on the macroscopic mechanical behaviors of the material, and among which, the bond strength is negatively related to temperature and positively related to strain rate. On the macroscopic level, the effects are corresponded to the same development tendency between the peak strength and the temperature and strain rate. Further analysis on the shear band formed during the FPC particles displacement indicates that the inclination angle of the shear band is negatively related to temperature, while the strain rate has little influence on it. According to the available data, the statistic relationship between the shear band inclination angle and friction angle is consistent with the Mohr-Columb solution.