Thermal jet drilling of granite rock: a numerical 3D finite-element study

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’.

A study on the physical and mechanical properties of a granite outcrop for a quarry at Onikoko community, Oyo State, South-Western Nigeria

Purpose. To investigate the physical and mechanical properties of a granite outcrop for a quarry at Onikoko community in Oyo State, South-Western Nigeria. Methods. Samples of granite rock were collected from the outcrop for the laboratory determination of their physical and mechanical properties required for determining its suitability for construction and engineering purposes, and the desired properties were determined. Findings. Results from the tests conducted on the granite samples indicated the various values of physical and mechanical properties of the outcrop in the study area. The results obtained are found to be within the acceptable international standards. Hence, the granite outcrop is found to be suitable for establishing a quarry in the study area based on the results obtained. Originality.The results in this study have affirmed the fact that granite rocks must possess adequate physical and mechanical characteristics to make them suitable for construction and engineering purposes. The physico-mechanical properties of the granite outcrop evaluated in this study having their values within the international standards attest to high strength cha-racterization of the granite rock. The life span of the proposed quarry is established to be forty years, which is also an indication of rich mineralization of the area. Practical implications. Results of this study can be a useful source of information to potential investors and policy makers for the establishment of a quarry in the study area. Hence, government’s attention can be drawn to the needs of the host community for the provision of basic infrastructures. Keywords: granite outcrop, physical and mechanical properties, quarrying operation