An arched tunnel is driven in moderately blocky and seamy, wet ground at a depth of 863 m where rock properties are, Co = 98.6 MPa, To = 9.86 MPa, E = 29.3GPa, G = 12.4GPa, γ = 24.7kN/m3. The tunnel is 4.3 m wide by 5.2 m high; the back arch is semi-circular. Specify a suitable steel set size (web depth, flange width, weight per foot), set spacing and maximum blocking point spacing for these conditions.