基于微观矿物含量的灰岩细观参数标定研究

随着对岩体力学研究的深入,宏微观岩体力学的研究方法发展迅速。但岩体微观性质改变对引起岩体宏观力学各向异性行为的影响研究却较为缺乏,而在离散元分析方法中,岩体宏观力学行为的准确表征不仅需要合理的细观强度参数,也需要考虑岩体中微观矿物的成分和含量。以灰岩为研究对象,制作灰岩薄片标本,用偏光显微镜观察灰岩样本以确定矿物成分及含量,并以此为依据生成基于矿物含量的离散元模型,以接触软化接触模型模拟矿物间的细观力学行为。分别建立与室内试验对应的单轴压缩模型和巴西劈裂模型,使用试错法不断调整细观强度参数,最终使细观模型表现出的宏观力学性质与实际情况一致。研究结果表明,数值模拟得到的宏观参数与室内试验结果相吻合,说明基于微观矿物含量的岩体离散元模型参数标定方法能够很好地标定出颗粒的细观强度参数,同时细观强度参数又能够很好地表征岩体宏观力学强度,以该参数作为岩体力学响应分析的输入参数,能够更准确认识岩体的力学行为。

Study on the Calibration of Meso-scale Parameters of Limestone Based on Microscopic Mineral Content

The research methods of macro and micro rock mechanics have developed rapidly with the in-depth study of rock mechanics. However, there is a lack of research on the influence of rock microscopic property changes on causing the macroscopic mechanical anisotropic behavior of rock masses. In discrete element analysis methods, the accurate characterization of the macroscopic mechanical behavior of rock masses requires not only reasonable fine-scale parameters but also the composition and content of microscopic minerals in rocks. Thin section specimens of limestone were made to determine the mineral composition and content polarized light microscope. Mineral content-based discrete element models were established, and the microscopic mechanical behaviors among minerals were simulated with the contact softening model. The uniaxial compression and the Brazilian splitting models corresponding to the indoor tests were established. The microscopic strength parameters were adjusted using the trial-and-error method to make the macroscopic mechanical properties of the microscopic model consistent with the actual situation. The results show that the macroscopic parameters obtained from the numerical simulations are consistent with the results of the indoor tests, indicating that the parameter calibration method of the discrete element model based on the microscopic mineral content of the rock mass can well calibrate the meso-scale parameters of the particles. The meso-scale strength parameters can well characterize the macroscopic mechanical strength of the rock mass, which can be used as the input parameters for the mechanical response analysis of the rock mass to understand the mechanical behavior of the rock mass more accurately.