基于UDEC颗粒模型的不确定性分析

颗粒模型的不确定性(颗粒形状、大小及空间分布等)严重影响岩石(体)数值模拟结果的可靠性与合理性。基于UDEC软件中的Voronoi颗粒模型,提出了两种Trigon颗粒模型的建立方法并通过软件自带的FISH语言实现。同时,深入分析了单轴压缩条件下颗粒形状、迭代次数(颗粒大小)和随机种子数(颗粒空间分布)对煤岩试样宏观力学行为及其破坏模式的影响。研究结果表明,迭代次数和随机种子数对煤岩单轴抗压强度及其变形特性的影响与颗粒形状相关:对于Trigon颗粒模型,两者影响程度相当;对于Voronoi颗粒模型,随机种子数的影响明显大于迭代次数。煤岩试样破坏过程中产生的微裂纹类型、数量及其发展规律主要受颗粒形状的影响,而受迭代次数和随机种子数的影响不大。岩石试样的破坏模式同时受颗粒形状、迭代次数和随机种子数的影响。因此,真实考虑岩石(体)组成物质的颗粒形状、大小及其空间分布,可有效提高颗粒模型数值模拟的真实性与可靠性。

Analysis of uncertainty in UDEC grain-based model

The uncertainty in the grain-based model, such as grain shape, size and spatial distribution, has a significant effect on the reliability and reasonability of numerical simulation for rocks. Based on the Voronoi model in UDEC, two modified Trigon models were proposed and realised through the built-in programming language FISH. Meanwhile, the effects of grain shape, iteration and random seed on the macroscopic response and failure mode of the coal sample were analysed in uniaxial compression test. The results showed that the effects of iteration and random seed on uniaxial compression strength and deformation of coal samples depended on the grain shape. For the two Trigon models, the influences of iteration and random seed were similar. However, for the Voronoi model, the influence of random seed was greater than that of iteration. Furthermore, the type, number and development of cracks were mainly affected by the grain shape. The failure modes of the coal sample were determined by the grain shape, iteration and random seed. Hence, the reliability of numerical simulation in the UDEC grain-based model can be improved by considering the real grain shape, grain size and spatial distribution of rocks.