Abstract:

The development of transportation in large cities requires the construction of tunnels. In many tunnelling projects, surface settlements have been observed. Most of the cases reported in the literature focus on considering the effect of ground conditions, tunnel size, depth, surface loads, and construction process on the ground surface settlement. However, the effect of joints between segments is not considered in the precast concrete lining in these cases. A numerical study of the settlements above a tunnel at the Bologna metro project is performed which made it possible to include the influence of joint characteristics such as joint number, joint distribution, joint rotational stiffness and deformability of ground on the surface settlement. Analysis is carried out using a two-dimensional finite difference element model. The results show a negligible influence of joint distribution, joint number and joint rotational stiffness on the surface settlement. On the other hand, the Young’s modulus of the ground must be well known due to its significant influence