The thermal cracking mechanism has been increasingly investigated to analyse and solve the mechanical behaviour of rocks in deep underground engineering. Classic laboratory tests bear the intrinsic limitation of non-repeatability and lack of direct observation of the interaction effect between thermal stresses and thermal micro-cracks. In this paper, the bonded-particle model and moment tensor is used to simulate the process of thermally induced micro-and macro-cracks in Lac du Bonnet granite to help provide insight into the detailed influence temperature on mechanical properties and acoustic emission characteristic of granite. During modelling, macro- and microscopic responses are quantified and compared against other laboratory data in the literature. The results indicate thermal stresses and thermally induced micro-cracks increase with increasing temperatures during heating, and cooling generally reduces the thermal stresses and increases the micro-cracks slightly. Grain-size distribution has a significant influence on thermal micro-cracks, thermal stress and the mechanical behaviours of granite. The increase in thermally induced tensile intergranular micro-cracks density mainly contributes to reduction of mechanical properties in granite samples subjected to heating–cooling cycles. It is also observed that the nature of sources and the b-value are associated with temperature, which gives some light on underground engineering in high temperature environments.

人们已经对热裂机理进行了越来越多的研究，以分析和解决深层地下工程中岩石的力学行为。经典的实验室测试具有不可重复性的固有局限性，并且无法直接观察到热应力和热微裂纹之间的相互作用。本文使用键合颗粒模型和矩张量来模拟Lac du Bonnet花岗岩中热诱发的微裂纹和宏观裂纹的过程，以帮助深入了解温度对花岗岩力学性能和声发射特性的影响。 。在建模过程中，对宏观和微观响应进行了量化，并与文献中的其他实验室数据进行了比较。结果表明，在加热过程中，热应力和由热引起的微裂纹会随着温度的升高而增加，而冷却通常会降低热应力，并使微裂纹略微增加。粒度分布对热微裂纹，热应力和花岗岩的力学行为有重要影响。热致拉伸晶界微裂纹密度的增加主要是导致经受加热-冷却循环的花岗岩样品的机械性能降低。还观察到，来源的性质和 热致拉伸晶界微裂纹密度的增加主要是导致经受加热-冷却循环的花岗岩样品的机械性能降低。还观察到，来源的性质和 热致拉伸晶界微裂纹密度的增加主要是导致经受加热-冷却循环的花岗岩样品的机械性能降低。还观察到，来源的性质和b值与温度有关，这为高温环境下的地下工程提供了一些启示。