摘要
岩石材料的宏观力学性能受到其细观结构的控制作用,随着岩石多尺度力学研究的不断深入,具有颗粒可破碎特性的颗粒离散元模型逐渐成为该研究领域的有力工具。以往的研究较少考虑晶内网格形态与岩石矿物晶体结构的对应关系,关于晶内网格形态对颗粒模型计算结果影响规律的研究也相对缺乏,这不利于模型的进一步精细化构建以及对不同模型计算结果的对比分析。在已有研究的基础上,采用Neper插件结合通用离散元程序,并综合考虑矿物晶体的解理特性构建了6种晶内网格划分模式。基于单轴压缩模拟试验分析了不同划分方式对计算结果的影响作用。结果表明,所提出的晶内网格构建方式可以再现矿物颗粒的解理特征,为离散元模型的精细化构建提供了多种选择;晶内网格形态差异对抗压强度的影响最明显,而对泊松比和弹性模量的影响较小;宏观力学参数的稳定性受子颗粒形状和晶内路径方向均匀度的共同影响,其中子颗粒形状的影响更为显著;微裂纹的数量主要与子颗粒几何特征有关,多边形子颗粒相比于三角形子颗粒更易引发岩石破坏时微裂纹总体数量的增加;子颗粒圆形度的增加会减弱颗粒间的互锁作用,从而导致裂纹数量降低。因此,在使用岩石颗粒离散元模型时应充分考虑模型构建方法对于计算结果的影响作用,从而提高仿真计算的可靠度。
Macroscopic properties of rock materials are controlled by their meso-structures.With the continuous development of rock multi-scale mechanics research,the grain-based model(GBM)with grain breakable characteristics has gradually become a powerful tool in this field.The corresponding relationship between the intragranular mesh morphology and the crystal structure of rock minerals has received less attention in previous studies.Research on the influence of the intragranular mesh morphology on the calculation results of the grain-based model is relatively limited,which is not conducive to the further refinement of the model and the comparative analysis of calculation results of different models.Based on the existing research,using the Neper plug-in combined with Universal Distinct Element Code,six intragranular meshing modes are established comprehensively considering the cleavage characteristics of mineral crystals.The influence of different intragranular mesh methods on the calculation results is analyzed based on the uniaxial compression simulation test.Results show that the proposed intragranular mesh method can reproduce the cleavage characteristics of mineral grains,therefore provide a variety of options for the refined construction of discrete element models.The difference of intragranular mesh mode has the most obvious influence on uniaxial compression strength but has little influence on Poisson′s ratio and elastic modulus.The stability of mechanical parameters is jointly affected by the shape of the sub-grains and the uniformity of the intragranular path direction,The shape of the sub-grains has a more significant effect.The amount of microcracks are mainly related to the geometric characteristics of the sub-grains.Compared with the triangular sub-grains,the polygonal sub-grains are more likely to cause an increase in the overall number of micro-cracks.The increase in the roundness of sub-grains will weaken the interlocking effect between the grains,resulting in a decrease in the number of cracks.Therefore,the influence of the model construction method on the calculation results should be fully considered when using the GBM so as to improve the reliability of simulation.
作者
张乘菡
由爽
纪洪广
ZHANG Chenghan;YOU Shuang;JI Hongguang(Beijing Key Laboratory of Urban Underground Space Engineering,University of Science and Technology Beijing,Beijing 100083,China;School of civil and resource engineering,University of Science and Technology Beijing,Beijing 100083,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2021年第S02期749-758,共10页
Journal of China Coal Society
基金
国家自然基金面上资助项目(51774021)
国家自然基金面上资助项目(52074021)
山东省科技重大创新资助项目(2019SDZY05-01)
关键词
深部硬岩
细观结构
离散元方法
颗粒模型
晶体解理
微裂纹
deep hard rock
meso-structure
distinct element method
grain-based model
crystal cleavage
microcracks
