With reference to Problem 4.34, specify support in the form of rock reinforcement by bolting on a square pattern that has the same support capacity (bolt diameter, spacing, length, steel strength)....

With reference to Problem 4.34, specify support in the form of rock reinforcement by bolting on a square pattern that has the same support capacity (bolt diameter, spacing, length, steel strength).

Problem 4.34

An arched tunnel is driven in moderately blocky and seamy, wet ground at a depth of 2,830 ft where rock properties are:

C_o
= 14,300 psi, T_o
= 1,430 psi, E = 4.25 (106) psi, G = 1.8 (106) psi, γ = 156 pcf

The tunnel is 14 ft wide by 17 ft 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.