Choosing Appropriate Parameters for Developing Empirical Shear Strength Criterion of Rock Joint: Review and New Insights

Excerpt

The strength of rock mass is significantly influenced by the shear strength of rock joints embedded in the rock mass. Therefore, an accurate determination of joint shear strength is important for assessing the engineering stability of rock mass. Various factors, including rock type, joint surface roughness, joint size and fillings, affect the shear strength of rock joints, and among them, we can highlight surface roughness and rock strength. It is not easy to exactly predict the shear strength of rock joints due to a number of complex attributing factors. In the past decades, various methods have been adopted to describe the shear strength, such as empirical (Patton 1966; Barton 1973; Barton and Choubey 1977; Maksimovic 1992; Kulatilake et al. 1995; Zhao 1997; Grasselli and Egger 2003; Xia et al. 2014; Tang and Wong 2016), semi-theoretical (Ladanyi and Archambault 1969; Seidel and Haberfield 1995) and theoretical (Lanaro and Stephansson 2003). The JRC–JCS criterion, proposed by Barton and Choubey (1977), is the only one widely used in rock engineering practice. The limitations of the criterion have been stated by many researchers, including the roughness parameter of joint surface (Kulatilake et al. 1995; Beer et al. 2002; Hong et al. 2008), the strength parameter of rock material (Grasselli and Egger 2003; Ghazvinian et al. 2012; Xia et al. 2014; Tang and Wong 2016) and the peak dilatancy function (Ghazvinian et al. 2012). Recently, with the technological advances, such as optical topography instrument, several empirical criteria based on objective three-dimensional parameters have been developed (Grasselli and Egger 2003; Xia et al. 2014; Tang and Wong 2016). However, limitations behind the mathematical expression and the physical constraints should not be ignored. The main shortcomings of those proposals include the validity of power or logarithmic relationship based on the phenomenon observed experimentally, limited stress range and the lack of physical meaning (Maksimovic 1992). According to Ghazvinian et al. (2012), a satisfactory criterion could be proposed only when we choose the necessary appropriate parameters, such as roughness parameter, rock strength and also their combination. Thus, the development of an empirical relationship which can satisfactorily explain the frictional behavior of rock joint using appropriate parameters is the scope of the present study. …