Structural stability and bearing capacity analysis of the tunnel-entrance to the stadium of Ancient Nemea

In the archaeological site of Ancient Nemea, Greece, southeast of the Temple of Zeus, is an ancient stadium in which the athletes of the past entered through a 36-m tunnel-a cut-and-cover vaulted structure, constructed of limestone. The tunnel was buried with earth until it was discovered in 1978. At present, some limestone blocks of the tunnel show appreciable damage mainly due to the humidity fluctuation within the tunnel. This study presents a comprehensive structural analysis of the tunnel, ranging from the thrust line limit analysis and the discrete element method to a three-dimensional finite-element analysis of the tunnel and its surrounding soil. The study concludes that the tunnel with its overburden-surrounding soil is structurally stable and has ample bearing capacity. The study also shows that the stones that suffer the most noticeable exfoliation due to the humidity fluctuation are those for which their visible surface from the inside of the tunnel is in compression. In conclusion, selective stones of the structure need to be retrofitted in order to avoid further local failures, while the humidity fluctuation inside the tunnel needs to be minimized.