Anisotropies in Mechanical Behaviour, Thermal Expansion and P-Wave Velocity of Sandstone with Bedding Planes

Many geo-engineering applications, such as geological repositories for nuclear waste, geological sequestration of CO2, enhanced geothermal systems, deep mining and deep well drilling involve thermal, hydraulic, mechanical and chemical interactions. Describing these coupling processes requires knowledge of each individual process and their coupling effects (Kohl et al. 1995; Hudson et al. 2005; Poulet et al. 2012; Jobmann and Polster 2007). A number of investigations (Maruyama et al. 2014; Zhu et al. 2015; Duchkov et al. 2014; Nagaraju and Roy 2014; Fortin et al. 2011) on various rock materials have indicated that the elastic modulus, strength, thermal conductivity and seismic properties of rock materials are dependent on their porosity, saturation degree, saturating uids and damage. Furthermore, there are correlations between the physical and mechanical properties, and some theoretical and empirical relations have been proposed for different rocks (Yasar and Erdogan 2004; Gruescu et al. 2007; Hovis et al. 2008; Chen et al. 2012). Anisotropies are usually observed in rock materials and cause the physical and mechanical properties to vary with direction because of the presence of bedding planes, schistosity planes, structural discontinuities and stress-induced defects (Gao et al. 2015; Davis et al. 2007; Bourret et al. 2015; Qin et al. 2015; Wenk et al. 2012).