基于直剪试验的堆积碎石类材料细观参数标定方法及模拟验证

颗粒材料三维离散元数值模拟的可靠性取决于细观参数的合理标定，目前对细观模拟参数的标定方法还缺少系统性的研究。本文通过室内直剪试验和数模试验对比分析，揭示碎石颗粒材料宏观力学参数与颗粒间细观参数的相关性，提出碎石颗粒材料数值模拟细观参数的标定方法，并验证标定方法的合理性。研究结果表明：在线性模型中，碎石颗粒试样的宏观弹性常数与碎石的粒间法向接触刚度呈正相关，而对粒间切向接触刚度的变化不敏感，基于此提出的粒间接触刚度（法向、切向）标定方法；直剪数值试验的剪应力-剪位移曲线计算结果与室内试验值吻合度较高，结果验证了标定方法的可靠性及合理性；在直接剪切过程中，碎石颗粒内部力链网络随着剪位移的增加逐渐由垂直方向向剪切盒对角线方向偏转，随着颗粒的整体速度场变化而出现剪缩和剪胀现象；采用本文提出的细观参数标定方法对室内滑坡运动试验开展数值模拟，数值模拟滑坡碎石堆积形态与室内试验基本一致，验证了该方法在堆积碎石滑坡模拟分析中的适用性。

Mesoscopic Parameter Calibration Method of Accumulated Debris Materials Based on Direct Shear Test and Simulation Verification

The reliability of three-dimensional discrete element numerical simulation of granular materials depends on the reasonable calibration of mesoscopic parameters. At present, systematic research on calibration method of mesoscopic parameters is lacked. Based on the comparative analysis of indoor direct shear test and numerical simulation, the correlation between the macroscopic mechanical parameters of granular materials and the mesoscopic parameters of particles is revealed. Besides, the calibration method of the meso parameters of the numerical simulation of granular materials is proposed, and the rationality of calibration method is verified. The research result show that: in the linear model, the macro elastic constant of the sample is positively correlated with the normal contact stiffness of the particles, but not sensitive to the change of the tangential contact stiffness. Based on this, the calibration method of contact stiffness (normal and tangential) of particles is proposed. The shear stress-shear displacement curve of the numerical direct shear test is well agreement with the experimental value, so the reliability and rationality of the calibration method are verified; Through the numerical test of the direct shear of gravel, it is found that the internal force chain network of the particles deflects from the vertical direction to the diagonal direction of the shear box with the increase of shear displacement, and the shear shrinkage and expansion occur with the change of the overall velocity field of the particles during the shear process. The meso parameter calibration method proposed in this paper is used to conduct numerical simulation of indoor landslide motion test. The morphology of landslide gravel accumulation in numerical simulation is consistent with the indoor test well, which verifies the applicability of the calibration method in the simulation analysis of accumulated gravel landslide.