A rectangular shaft 3 m × 6 m with the long axis parallel to the N–S line exists at a depth of 290 m. The mining plan calls for deepening the shaft to 550 m. The premining stress state relative to compass coordinates is: SE = 3,414 + 4.5h, SN = 2, 897 + 7.9h, SV = 25.3h where stresses are in kPa, h = depth in m, E, N, V refer to compass coordinates (x = east, y = north, z = up) and compression is positive. Premining shear stresses are nil relative to compass coordinates. Rock properties are: Co = 163.5 MPa, To = 10.2 MPa, E = 36.48Gpa, ν = 0.27, γ = 25.6kN/m3. A second shaft of identical shape is also planned to the new depth of 550 m. Show a location and orientation (plan view) of the two shafts that is most favorable with respect to stress concentration and explain the basis of your choice.