Differential settlement is a big issue for an immersed tunnel. This will lead to large stress concentrations in the tunnel construction, giving rise to local cracking, failure of the construction, leakage, deterioration of exposed rebar, etc. Variety factors will influence it, like the consolidation process, the action time of different loads when construction, and the sub-soil condition, etc. To protect the integrity of the structure, settlements should be kept within limits. Although the immersed tunnels are generally designed to withstand buoyancy by a margin of 4%, the settlements have been observed which severely exceed the predictions in the Kiltunnel. In this case, a complicating factor is a fact that the dikes on both sides have been reconstructed after immersing the elements, but not at the same location as before the immersion trench was dredged. Consolidation (at first) and creep due to this relatively new load on the subsoil can play a role as well. These aspects contribute to the problem of the differential settlements which have resulted in leaking joints and consequently increased maintenance costs. In addition, how and to what extent uneven settlement affects the structural safety of tunnels and their users, and how to reduce the durability of tunnels are unknown. As a result, it is necessary for us to do research about the settlement in Kiltunnel.