A 12 ft by 24 ft rectangular shaft is sunk to a depth of 3,000 ft in

Question:

A 12 ft by 24 ft rectangular shaft is sunk to a depth of 3,000 ft in ground where the premining stress field is given by formulas S_v = 1.2h, S_h = 120 + 0.5h, S_H = 3, 240 + 0.3h where h is depth in feet and the stresses are in psi. Show by sketch, the best orientation of the shaft relative to the directions of h and H. Is this the best orientation at all depths to 3,000 ft?