A 10m diameter circular tunnel is to be excavated in a jointed ground. The joint sets spaced at 6m are dipping towards the West at 50°. A horizontal circular tunnel is to be constructed approximately parallel to the joint direction. Occasional near vertical minor fault planes are present in the area. The depth of the tunnel is approximately 550m and density of rock is 2.5t/m3.
Assume a uniform hydrostatic stress within strata. The rock and joint properties are given in Table 3 below.