Direct Shear Behavior of Planar Joints Under Cyclic Normal Load Conditions: Effect of Different Cyclic Normal Force Amplitudes

Excerpt

The strength of joints under complicated stress conditions has to be analyzed to evaluate the stability of tunnels, foundations and underground excavations. In particular, static loads superimposed by dynamic excitations produced by earthquakes or vibrations induce complex stress pattern. Stein (1999) already proved that an earthquake alters the shear and normal stresses on surrounding faults. Understanding the dynamic behavior of rock masses and especially joints as weak elements inside them is essential for the design of engineering projects, e.g., for surface and underground excavations, slopes, dam foundations or geothermal reservoirs (e.g., Barton and Choubey 1977; Crawford and Curran 1981; Kana et al. 1996; Lee et al. 2001; Jafari et al. 2003; Bagde and Pertros 2005; Petros and Bagdewas 2005; Belem et al. 2007; Ferrero et al. 2010; Guo et al. 2011; Liu et al. 2011, 2012a; Konietzky et al. 2012; Cabalar et al. 2013; Tao et al. 2013; Thevenet et al. 2013; Lee et al. 2014; Mirzaghorbanali et al. 2014; Nguyen et al. 2014; Zhou et al. 2015, 2017; Du et al. 2016; Zhu et al. 2016; Li et al. 2016, 2017; Dang 2017), but also for geological hazard evaluation (e.g., Hoek and Brown 1980; Hoek and Bray 1981; Babanouri et al. 2011; Liu et al. 2012b, 2013; Liu and Dang 2014; Lin et al. 2015). …