The intact rock that follows the Mohr–Coulomb failure criterion has c = 15 MPa and ϕ = 27°. Estimate the uniaxial compres sive strength σc, the uniaxial tensile strength σt and the Brazilian indirect tensile strength σ′ t . Give an estimate of the point load strength index Is(50) and suggest a realistic range for the Young’s modulus E.

9. A rock mass is cut by one set of joints with spacing S = 0.40 m. (a) If the joint normal and shear deformations are assumed to be equal to that of the rock itself, express k, and k,, in terms of E and v. (b) Assuming E= 104 MPa and 0.33, calculate all the terms of the strain-stress relationship for an equivalent transversely isotropic medium, (corresponding to Equation 6.9).

In a zone with a constant stress gradient of a mechanical- structural element, the stresses acting in the "x" direction are Ox = 5900 psi and Txy = 1950 psi. Determine the allowable values if the maximum shear stress is limited to Tmax = 2500 psi. for Ty

For the rock element, shown: Calculate the following stresses of interest Maximum Principal Stress Minimum Principal Stress Maximum Shear Stress Normal Stress at Failure Plane A-B Shear Stress at Failure Plane A-B SHOW COMPLETE SOLUTION