Abbreviations
- \(b\) :
-
Width of rock block
- \(c\) :
-
Constant relating to calculate boundary normal stiffness
- \(c_{0} ,c_{1} ,c_{2}\) :
-
Empirical constants defining joint dilation rate
- \(F\) :
-
Support force
- \(E_{\text{r}}\) :
-
Young’s modulus of rock mass
- \(i\) :
-
Dilation angle
- \({\text{JRC}}\) :
-
Joint roughness coefficient
- \({\text{JCS}}\) :
-
Compressive strength of joint surface
- \(K_{\text{n}}\) :
-
Normal stiffness at an external boundary
- \(K\) :
-
Ratio of horizontal stress to vertical stress
- \(k_{\text{ni}}\) :
-
Initial normal stiffness of joint
- \(k_{\text{s}}\) :
-
Shear stiffness of joint
- \(L\) :
-
Length of rock block
- \(M\) :
-
Damage coefficient
- \(N_{0}\) :
-
Initial normal force
- \(p\) :
-
Vertical stress component
- \(R\) :
-
Radius of tunnel
- \(r\) :
-
Radial distance of the point from the centre of opening
- \(S_{0}\) :
-
Initial shear force
- \(V_{\text{m}}\) :
-
Maximum joint closure
- \(W\) :
-
Weight of rock block
- \(z\) :
-
Depth below surface
- \(\dot{v}\) :
-
Dilation rate
- \(\dot{v}_{\text{peak}}\) :
-
Peak dilation rate
- \(\alpha ,\beta ,\lambda\) :
-
Components relating to shear stress-shear displacement equation
- \(\theta\) :
-
Polar angle with respect to horizontal axis \(x\)
- \(\psi\) :
-
Polar angle with respect to vertical axis \(y\)
- \(\gamma_{\text{r}}\) :
-
Unit weight of rock mass
- \(\delta_{\text{h}}\) :
-
Shear displacement
- \(\delta_{\text{h - peak}}\) :
-
Shear displacement at peak stress ratio
- \(\sigma\) :
-
Normal stress
- \(\sigma_{\text{n}}\) :
-
Normal stress at shear displacement \(\delta_{\text{h}}\)
- \(\sigma_{{{\text{n}}0}}\) :
-
Initial normal stress (at \(\delta_{\text{h}} = 0\))
- \(\sigma_{\text{rr}}\) :
-
Radial stress component
- \(\sigma_{{{\text{r}}\theta }}\) :
-
Shear stress component
- \(\sigma_{\theta \theta }\) :
-
Tangential stress component
- \(\tau_{\text{mob}}\) :
-
Mobilised shear stress
- \(\tau\) :
-
Shear stress
- \(\bar{\tau }\) :
-
Average shear stress along the vertical joints
- \(\phi_{\text{b}}\) :
-
Basic friction angle of joint
- \(\phi_{\text{mob}}\) :
-
Mobilised friction angle
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Acknowledgments
The authors would like to thank the Australian Research Council (ARC) Linkage Project for the financial support of the lead author’s doctoral studies.
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Thirukumaran, S., Indraratna, B., Brown, E.T. et al. Stability of a Rock Block in a Tunnel Roof Under Constant Normal Stiffness Conditions. Rock Mech Rock Eng 49, 1587–1593 (2016). https://doi.org/10.1007/s00603-015-0770-6
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DOI: https://doi.org/10.1007/s00603-015-0770-6