1. EGEE 520 Spring Semester, 09 Speaker: Amirreza Ghasemi

2. There are two main methods to calculate rock mass modulus: ASTM Standard UNAL Method

3. VW I = VW E  VW E = Boundary forces (f) × Boundary Displacements (virtual) (u)  VW I = Body strain resulting from virtual displacement ( ɛ ) × Stress change due to boundary conditions (σ) f = K u K= ∫ v a T.D.a.dv

5. 20 GPa0.796 mm ?0.9022 mm ?= 0.796/0.9022 * 20 = 17.6

6. ASTMUNALCOMSOL Min.10.50.6 Max.463939.0 Mean12.612.412.6 Median1089.0 Mode736.0 STD.9.110.29.9 Skewness1.10.9 Count69

7. ν= 0.2ν= 0.25 ν= 0.3 (Base Case) ν= 0.35 Min. 0.6 0.5 Max. 42.140.939.037.7 Mean 13.513.112.612.1 Median 9.49.29.08.4 Mode 856.06 STD. 10.510.39.99.4 Skewness 0.9 Count 69

8.  Results from ASTM, Unal, and COMSOL show very good consistency between different methods.  Sensitivity analysis shows that Rock mass modulus is not very sensitive to change in Poisson's ratio.