A circular concrete shaft liner with Young’s modulus of 3.4 million psi, Poisson’s ratio of 0.25, unconfined compressive strength 3,500 psi and tensile strength 350 psi is loaded to the verge of failure in dry ground. If the inside shaft diameter is 22 ft and the liner is one foot thick, what is the contact pressure between rock and liner, assuming it is uniform (psi)?