| It has been recently reported that ground heaves threatened the stability of road tunnels and the safety of road users during the maintenance stage. Constructing additional invert is effective to reinforce the tunnels, however it would require a lot of time and cost to excavate the bottom of the tunnels using a small machinery if a part of the lanes could be open to the traffic. The purpose of this research is to propose new invert structure that enable to reduce the volume of the excavation. Model experiments were conducted to compare the load- bearing performances between the standard and the 3 newly proposed inverts, for example, the shape of which was flat. As a result, the maximum loads of the proposed inverts, which could reduce the volume of the excavation 30-50%, were slightly over 50% of that of the standard one. It was also found that the failure processes of the 4 test cases were different, therefore they were evaluated in terms of not only the maximum loads but also the capabilities to restrain the ground heave and to transfer bending moment and axial force by analysing the measured deformations and strains of the tunnel models. |
