Characterization of tunnel segment fire behavior: use of nondestructive technics

Pierre Pimienta (1) , Benoît-Louis Marie-Jeanne (1) , Roberto Felicetti (2)

1 CSTB - Centre Scientifique et Technique du Bâtiment
2 POLIMI - Politecnico di Milano [Milan]

Two twin tunnels have been constructed to cross the Suez Canal in Egypt, one at Port Said near the North entrance of the Suez Canal and one at Ismailia city in the midst of the Canal. The report presents the results of the fire tests on full size segments from the tunnel at Port Said. Five segments equipped with thermocouples were manufactured by CJV close to the tunnel site in August 2017. Two commercial tests were carried out for the client Orascom in 2018 at the age of 5 months. CSTB and Politecnico de Milano have carried out an additional full-scale fire resistance test on a segment in July 2019 at the age of 23 months. The same experimental procedure as for the other segments has been applied. Mechanical stresses on the segments were applied as a combination of vertical and horizontal loads to simulate the maximum in situ stresses exerted on the tunnel lining due to earth and water pressure. Concrete segment samples were subjected to the well-known RWS temperature curve (with a maximum temperature of 1350 °C) for a duration of 2 hours. Temperatures loads and displacements at different locations were recorded, during the heating and the cooling phases. The main aim of the test was to assess the sacrificed thickness of concrete and quantify the spalling phenomena during fire testing. Values will be compared with the ones determined on the 2 previous samples. Spalling depth fields have been measured about 2 hours after the end of the test with a 3D laser scanner. The importance of measuring depth quickly after testing when severe temperature curves are applied on concrete samples will be discussed. A new non-destructive technic has been employed during the test: ultrasonic Pulse Echo (UPE). This technic was adapted by Politecnico de Milano to monitor concrete damage and spalling progression during a fire test. Findings from this innovative method are presented.

Mots clés: TUNNEL; FIRE RESISTANCE; FULL-SCALE EXPERIMENTS; CONCRETE SPALLING; ULTRASONIC PULSE ECHO (UPE)

Domaines: Mécanique des structures [physics.class-ph]; Matériaux et structures en mécanique [physics.class-ph]

Pierre Pimienta, Benoît-Louis Marie-Jeanne, Roberto Felicetti. Characterization of tunnel segment fire behavior: use of nondestructive technics. [Research Report] CSTB - Centre scientifique et technique du bâtiement; Politecnico di Milano. 2020. ⟨hal-02894917⟩