Table 1 Five elastic determination equations of transversely isotropic slate.

From: A damage constitutive model of layered slate under the action of triaxial compression and water environment erosion

The joint dip angle β(°)

Calculating equations

\(\beta = {0}^\circ\)

\(\frac{{\Delta \varepsilon_{x} }}{{\Delta \sigma_{r} }} = - \frac{{v_{2} }}{{E_{{2}} }}\) (10)

\(\frac{{\Delta \varepsilon_{y} }}{{\Delta \sigma_{z} }} = - \frac{{v_{2} }}{{E_{{2}} }}\) (11)

\(\frac{{\Delta \varepsilon_{r} }}{{\Delta \sigma_{r} }} = \frac{1}{{E_{{2}} }}\) (12)

\(\beta = {90}^\circ\)

\(\frac{{\Delta \varepsilon_{x} }}{{\Delta \sigma_{r} }} = - \frac{{v_{{1}} }}{{E_{{1}} }}\) (13)

\(\frac{{\Delta \varepsilon_{y} }}{{\Delta \sigma_{r} }} = - \frac{{v_{2} }}{{E_{{2}} }}\) (14)

\(\frac{{\Delta \varepsilon_{r} }}{{\Delta \sigma_{r} }} = \frac{1}{{E_{{1}} }}\) (15)

\(\beta = {45}^\circ\)

\(\frac{{\Delta \varepsilon_{x} }}{{\Delta \sigma_{r} }} = - \frac{{1}}{{2}}\left( {\frac{{v_{{1}} }}{{E_{{1}} }} + \frac{{v_{{2}} }}{{E_{{2}} }}} \right)\) (16)

\(\frac{{\Delta \varepsilon_{y} }}{{\Delta \sigma_{r} }} = \frac{{1}}{4}\left( {\frac{1}{{E_{1} }} + \frac{1}{{E_{2} }} - \frac{1}{{G_{2} }}} \right) - \frac{{v_{2} }}{{{2}E_{2} }}\) (17)

\(\frac{{\Delta \varepsilon_{r} }}{{\Delta \sigma_{r} }} = \frac{{1}}{4}\left( {\frac{{1}}{{E_{2} }} + \frac{{1}}{{E_{1} }} + \frac{1}{{G_{2} }} - \frac{{2v_{2} }}{{E_{2} }}} \right)\) (18)