English to Arabic Science Geology

Based on engineering judgement, and on the discussion in Section 4.2.8, a suitable and more appropriate range of Ko between 0.7 and 0.9 should be adopted for the tunnel lining design. This is based upon that, should higher Ko conditions still exist within the rock mass due to historic tectonic or overburden conditions and these loads are no longer present; and should the ground relax following excavation these forces cannot be remobilised thus leading to a lower long term in situ stress regime with overburden predominantly controlling stress conditions. Table 21 below summarises the range of values to be considered for the design of the tunnels.