Numerical modelling and simulation can be used to gain insight about rock excavation processes such as rock drilling. Since rock materials are heterogeneous by nature due to varying mechanical and geometrical properties of constituent minerals, laboratory observations exhibit a certain degree of unpredictability, e.g. with regard to measured strength and crack propagation. In this work, a recently published heterogeneous bonded particle model is further developed and used to investigate dynamic rock fracture in a Brazilian disc test. The rock heterogeneities are introduced in two steps—a geometrical heterogeneity due to statistically distributed grain sizes and shapes, and a mechanical heterogeneity by distributing mechanical properties using three Weibull distributions. The first distribution is used for assigning average bond properties of the grains, the second one for the intragranular bond properties and the third one for the bond properties of the intergranular cementing. The model is calibrated for Kuru black diorite using previously published experimental data from high-deformation rate tests of Brazilian discs in a split-Hopkinson pressure bar device, where high-speed imaging was used to detect initiations of cracks and their growth. A parametric study is conducted on the Weibull heterogeneity index of the average bond properties and the grain cement strength and evaluated in terms of crack initiation and propagation, indirect tensile stress, strain and strain rate. The results show that this modelling approach is able to reproduce key phenomena of the dynamic rock fracture, such as stochastic crack initiation and propagation, as well as the magnitude and variations of measured quantities. Furthermore, the cement strength is found to be a key parameter for crack propagation path and time, overloading magnitudes and indirect tensile strain rate.

数值建模和模拟可用于深入了解岩石开挖过程，例如凿岩。由于岩石材料由于组成矿物的不同机械和几何特性而本质上是异质的，因此实验室观察表现出一定程度的不可预测性，例如关于测量的强度和裂纹扩展。在这项工作中，进一步开发了最近发表的异质粘结颗粒模型，并将其用于研究巴西圆盘测试中的动态岩石断裂。岩石非均质性分两个步骤引入：由于统计分布的晶粒尺寸和形状而导致的几何非均质性，以及通过使用三个威布尔分布分布机械特性而导致的机械非均质性。第一个分布用于指定颗粒的平均粘结性能，第二个分布用于指定晶粒内粘结性能，第三个分布用于指定晶粒间胶结的粘结性能。该模型使用先前发布的分离式霍普金森压力棒装置中巴西圆盘高变形率测试的实验数据针对库鲁黑色闪长岩进行校准，其中使用高速成像来检测裂纹的萌生及其扩展。对平均粘结性能和颗粒水泥强度的威布尔异质性指数进行了参数研究，并根据裂纹萌生和扩展、间接拉应力、应变和应变速率进行了评估。结果表明，这种建模方法能够重现岩石动态断裂的关键现象，例如随机裂纹的萌生和扩展，以及测量量的大小和变化。此外，水泥强度被发现是裂纹扩展路径和时间、过载幅度和间接拉伸应变率的关键参数。