This paper presents a numerical study on thermal jet drilling of granite rock that is based on a thermal spallation phenomenon. For this end, a numerical method based on finite elements and a damage–viscoplasticity model are developed for solving the underlying coupled thermo-mechanical problem. An explicit time-stepping scheme is applied in solving the global problem, which in the present case is amenable to extreme mass scaling. Rock heterogeneity is accounted for as random clusters of finite elements representing rock constituent minerals. The numerical approach is validated based on experiments on thermal shock weakening effect of granite in a dynamic Brazilian disc test. The validated model is applied in three-dimensional simulations of thermal jet drilling with a short duration (0.2 s) and high intensity (approx. 3 MW m⁻²) thermal flux. The present numerical approach predicts the spalling as highly (tensile) damaged rock. Finally, it was shown that thermal drilling exploiting heating-forced cooling cycles is a viable method when drilling in hot rock mass.

This article is part of the theme issue ‘Fracture dynamics of solid materials: from particles to the globe’.

本文提出了一种基于热散裂现象的花岗岩岩石热喷钻的数值研究。为此，开发了一种基于有限元和损伤-粘塑性模型的数值方法，用于解决潜在的热力耦合问题。明确的时间步长方案用于解决全局问题，在当前情况下，该方案适合极端的质量缩放。岩石异质性被解释为代表岩石组成矿物的有限元的随机簇。该数值方法基于在动态巴西圆盘试验中对花岗岩的热冲击减弱作用的实验而得到验证。经过验证的模型应用于短时间（0.2 s）和高强度（约3 MW m）的热喷射钻井的三维模拟^-2）热通量。本数值方法将剥落预测为高度（拉伸）损坏的岩石。最后，研究表明，在热岩体中进行钻探时，利用加热强制冷却循环进行热钻探是一种可行的方法。

本文是主题主题“固体材料的断裂动力学：从粒子到地球”的一部分。