Grain-preferred orientation significantly influences the brittle fracture mechanism and failure mode of crystalline rocks. However, current grain-based models (GBMs) based on particle flow code (PFC) software are mostly proposed on the basis of the Voronoi tessellation method for grain boundary generation, which is difficult to simulate the heterogeneity of microstructure such as shape and orientation of rock minerals. To study the effect of grain-preferred orientation on macroscopic mechanical properties and microscopic characteristics of crystalline rocks, a novel grain-based microstructure transformation method (MTM) is proposed. Based on the MTM, a GBM with a target aspect ratio and crystal orientation is obtained by transforming the Voronoi crystal geometry through a planar coordinate mapping. Specifically, embedded FISH language is used to control random mineral seed size and distribution pattern to generate Tyson polygons. A polygon geometry that satisfies the rock texture is obtained as a grain boundary by spatially transforming the vertex of the Tyson polygon. The transformed complex geometry is taken as the crystal structure of the GBM, and the Lac du Bonnet granite models with different aspect ratios and crystal orientations were developed in PFC2D. Finally, a series of unconfined compressive strength tests are performed in PFC2D to verify the proposed modeling methods for the geometric variation of the crystals and to study the effects of the preferred orientation of the grains on the macroscopic mechanical properties and microscopic fracture mechanisms of the crystalline rocks from different perspectives.

中文翻译：

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晶粒择优取向对结晶岩石微裂纹和宏观力学行为影响的离散元模拟研究

晶粒择优取向显着影响结晶岩石的脆性断裂机制和破坏模式。然而，目前基于粒子流代码（PFC）软件的晶粒模型（GBM）大多是基于Voronoi曲面细分方法来生成晶界，难以模拟晶粒形状、取向等微观结构的非均质性。岩石矿物。为了研究晶粒择优取向对结晶岩石宏观力学性能和微观特征的影响，提出了一种新型的基于晶粒的微观结构转变方法（MTM）。基于MTM，通过平面坐标映射变换Voronoi晶体几何形状，获得具有目标长宽比和晶体取向的GBM。具体来说，嵌入式FISH语言用于控制随机矿物种子尺寸和分布模式以生成泰森多边形。通过对泰森多边形的顶点进行空间变换，得到满足岩石纹理的多边形几何形状作为晶界。将变换后的复杂几何形状作为GBM的晶体结构，在PFC中开发了具有不同纵横比和晶体取向的Lac du Bonnet花岗岩模型二维。最后，在PFC中进行了一系列无侧限抗压强度测试二维验证所提出的晶体几何变化建模方法，并从不同角度研究晶粒择优取向对晶体岩石宏观力学性能和微观断裂机制的影响。