Stress-Strain Behavior of Jointed Rock - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 42

anisotropic and can be described by transverse isotropy. Such an elastic behavior is speci-
fied by five independent elastic constants. Two Young's moduli E 1 and E 2 characterize the
deformability parallel and perpendicular to the structure planes. Parallel to a structure
plane the deformability is assumed to be isotropic. A structure plane is therefore called an
“isotropic plane”. The shear modulus G 2 describes the deformability for a shear loading
parallel to the isotropic plane. Furthermore, two Poisson's ratios

ν 1 and ν 2 are needed.

Figure 3.3 Definition of the elastic constants of an intact rock with planar grain structure and
transversely isotropic behavior (Wittke et al. 2006)

In Fig. 3.3 the elastic constants of a transversely isotropic rock are defined by means
of stresses and strains applied to a cube-shaped specimen using a Cartesian coordinate
system (x',y',z') that is related to the isotropic plane. The z' axis coincides with the direc-
tion perpendicular to the isotropic plane and the x' and y' axes lie in the isotropic plane.