It is accepted that heat waves, whose occurrence have been increasing throughout the last decades in the Iberian Peninsula, associated with climate change, are one of the main hazards linked to the occurrence of wildfires and the increase of fire risk in the open-pit mining industry. To the best of our knowledge, studies that relate the effect of temperature (produced by a fire) on jointed rock masses are scarce. This paper considers the development of benchmark work for the determination of the basic friction angle on suitably prepared saw-cut planar granitic joints, some of them subjected to thermal ageing, and by means of an automatic tilt test apparatus for both reference (no thermal ageing) and thermally aged samples. The results show the influence of high temperatures on the frictional behavior of rock joints, particularly relevant for the stability assessment after a fire or wildfire occurrence near outcrops and excavations.
It is widely accepted that climate change is leading, in the northern arc of the Mediterranean Sea, to temperature extremes that, in turn, causes the occurrence of fires and wildfires that affects many rock structures (Christensen et al., 2007; Meehl et al., 2007; Trenberth et al, 2007).
Rock thermal-induced decay has been the main focus of several studies already developed, most of them, in laboratory environment (e.g. Glover et al.,1995; Chopra, 1997; Zhang et al., 2001; McCabe et al., 2007; Tang et al, 2011; Heap et al., 2012; Ranjith et al., 2012; Zhao et al., 2012; Yang et al., 2014; Mao et al., 2015; Martinho & Dionísio, 2018; Paneiro et al., 2021). However, just a few works perform studies on what concerns the influence of high temperatures, like those induced by a wildfire in rock masses (Sarro et al., 2021).
Following the work of Alejano et al. (2017) and Pérez-Rey et al. (2020), the present paper presents the baseline results of the basic friction angles obtained from tilt tests on saw-cut planar joints on rock specimens subjected to different thermal ageing, namely 300°C and 700°C, and considering ambient moisture. These results correspond to a first incursion on assessing high temperature influence on rock mass stability.
