Analysis of surface settlement induced by DOT shield tunnel

An analysis was made of the characteristics of DOT(double-o-tube) shield tunnels,the influencing factors on the surface settlement and its calculation methods.Testing analysis shows that,as compared with the circular shield tunnel,the DOT shield tunnel is of some advantages,such as the low underground spatial occupancy,the diversification of tunnel cross-sections,the simple operation to ensure the balance of cutting faces,and the less soil excavation,and that the geometric shape and embedded depth of the shield tunnel,the construction interferences to soil property,the deformation of tunnel liners,the equilibrium pressure and form of the shield during the pushing process,and the synchronous grouting technique are the main factors influencing the surface settlement.Finally,it is concluded that the surface settlement induced by DOT shield tunnel is of the same mechanism with that by the circular shield tunnel,but the surface settlement induced by DOT shield tunnel is relatively large,and that the shape of settlement troughs induced by DOT shield tunnel can be expressed with the normal distribution function,but the maximum settlement does not always occur at the center of the tunnel.