The behavior of support measures applied to the Efpalineio tunnel, 10 years later
The behavior of support measures applied to the Efpalineio tunnel, 10 years later
The 1036m long Efpalineio tunnel on the island of Samos is an outstanding achievement of science and technology built in the 6th century BCE as part of the water supply aqueduct to the city of Pythagoreion. It is unique because it was the first known case where the tunnel was bored from both ends and the two bores met after many deviations from the straight line using applied geometry. The maximum overburden is 175m. The main tunnel is approximately 1.8x1.8m unlined in most of its length. Masonry lining has been applied in part of its northern section, either during initial construction or later during its operation. The tunnel was fully excavated and documented in the 1970s and some temporary support and protection measures were eventually applied. Although most of the tunnel was in very good condition there were locations where the stability of the walls and the safety of the visitors were inadequate.
The main problems included severe deformation of masonry linings, falling debris through open faults and/or the roof and advancing roof collapses.
A design of protection and support measures was made in 2010, and their construction was completed in 2015. Applied measures included steel netting, steel mesh, shotcrete in non-visible areas, rock bolts, partial filling of open faults, local dismantling of masonry lining and reconstruction after rock support, steel canopies, steel grid cover of the side trench, etc. All metallic elements were made of stainless steel.
The article briefly describes the protection and support measures, and presents their behavior over the first 10 years of application. Useful conclusions are drawn on the longevity of the support measures and proposals are made for future monitoring and maintenance.
George Dounias; Evryviadis Lyberis; Vasilis Gikas
4th International Symposium on the Preservation of Monuments and Historic Sites
Restoration Engineering and Structural Interventions
https://doi.org/10.53243/tc301-2026-83