Mechanical Properties of Sandstones Exposed to High Temperature

Excerpt

Modern rock engineering applications such as deep geological disposal of nuclear waste (Ringwood 1985; Gibb 1999; Hökmark and Claesson 2005; Gibb et al. 2008; Sanchez et al. 2012), geothermal heat (especially of hot dry rock) extraction (Zhao 2000; Ghassemi and Zhou 2011; Feng et al. 2012; Gelet et al. 2012; Cherubini et al. 2013), and underground coal gasification (Burton et al. 2007; Luo et al. 2011; Kempka et al. 2011; Younger 2011; Nakaten et al. 2014) experience high-temperature environments, where rocks generally experience high temperatures up to several hundred degrees Celsius. Consequently, rock behaviors under and after high-temperature conditions are of high interest and still a challenge to scientists and engineers of different disciplines. High temperatures result in thermal stresses and mineral expansion as well as various changes of physical and mineralogical properties within rock bodies (Hajpál and Török 2004; Tian et al. 2012a, 2013), and thus lead to micro-structure changes and micro-cracks development and extension (Den’gina et al. 1994; Dwivedi et al. 2008). These effects change rock mechanical properties such as elastic modulus and compressive strength under and after high-temperature treatment, from a macro point of view, compared to those at normal temperature. Therefore, corresponding high-temperature mechanical properties of rocks are of high relevance for successful implementation of underground rock engineering projects. …