Micro and macro-structural effects of high temperatures in Prada limestone: Key factors for future fire-intervention protocols in Tres Ponts Tunnel (Spain)
| Autor: | Víctor Martínez-Ibáñez, Roberto Tomás, M. E. Garrido, Carlos Hidalgo Signes |
|---|---|
| Přispěvatelé: | Universidad de Alicante. Departamento de Ingeniería Civil, Ingeniería del Terreno y sus Estructuras (InTerEs) |
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Cracks
Correlations INGENIERIA DEL TERRENO 09.- Desarrollar infraestructuras resilientes promover la industrialización inclusiva y sostenible y fomentar la innovación Intervention protocols Thermal damage Building and Construction Tunnel fire Limestone Ingeniería del Terreno Key factors Physical and mechanical properties Political science General Materials Science Macro PROYECTOS DE INGENIERIA Humanities Civil and Structural Engineering |
| Zdroj: | RUA. Repositorio Institucional de la Universidad de Alicante Universidad de Alicante (UA) RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia instname |
| Popis: | [EN] Temperature and cooling methods strongly affect the stability of tunnels drilled in rock masses and so condition interventions for fire emergencies. Samples from two horizontal boreholes drilled in Prada limestone during the design stage of the Tres Ponts Tunnel in the Catalan south Pyrenean zone (Spain) are heated from 105 to 600 degrees C, and subsequently cooled with air or water to simulate fire extinguishing interventions. Changes in chemical composition and microstructure, physical properties (open porosity, volume, dry total weight, P and S-wave velocity), and mechanical properties (uniaxial compressive strength, elastic modulus, and Poisson's ratio) are analysed. Rock weakening is observed even at low temperatures (T < 300 degrees C). The influence of the cooling method appeared at intermediate temperatures of 300-400 degrees C and open porosity, P and S-wave velocities, and elastic modulus show greater variation for water-cooled samples. A temperature of 500 degrees C is of paramount importance for 'Prada' limestone as it leads to a dramatic increase in porosity and a notable decrease in P and S-wave velocities under both cooling methods. Trans-granular micro-crack progression is observed at 500 degrees C using scanning electron microscope (SEM), and water-cooled samples show a greater loss in uniaxial compressive strength (UCS), and this is due to micro-crack connections and growing fissures. Thermal damage at 600 degrees C is also greater when samples are quickly cooled. An ANOVA and a simple regression analysis are performed to discard the influence of the natural location of the borehole samples in the obtained experimental results. Finally, correlations to predict UCS and elastic modulus from volume, open porosity, and P wave velocity after thermal treatment are proposed using simple exponential and potential functions to help make preliminary decisions after a tunnel fire. These predictive results on the effects of fire on Prada limestone will be considered for the definition of future fire intervention protocols in the Tres Ponts Tunnel. The authors wish to acknowledge Kreum SA, Ayesa SA, Infraestructures.cat, and the Lleida regional road authority (Servei Territorial de Carreteres de Lleida, Generalitat de Catalunya) for providing rock samples. Isidro Sanchez Martin from the Departamento de Ingenieria Civil of the Universidad de Alicante kindly helped us to analyse the MIP analyses, in addition, Mr. Manuel Angel Morilla Rubio and Salvatore Di Biase from the Universitat Politecnica de Valencia for their support on laboratory tests. This research was partially supported by the Vice-Rector of Research and Knowledge Transfer at the University of Alicante through projects UAUSTI19-25 and UAUSTI20-20, and by the Departamento de Ingenieria del Terreno at the Universitat Politecnica de Valencia. |
| Databáze: | OpenAIRE |
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