Impact of fire on tunnels in Hawkesbury sandstone

Smith, A. G.; Pells, P.J.N.

doi:10.1016/j.tust.2006.11.003

Cited by 29 publications

(7 citation statements)

References 6 publications

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“…Research reveals that water content can play a key role in the determination of UCS and the deformational features of the intact rock, even for small variations in the moisture content due to changes in the relative humidity of the air [44,45]. Natural moisture in rocks is also related to spalling events at temperatures lower than 200º C [7][8][9]. Even when water absorption in Prada limestone is extremely low (0.45±0.20 %), we decided to study its properties after moisture was completely removed by pre-heating the samples.…”

Section: Heating and Cooling Proceduresmentioning

confidence: 99%

“…Some studies are specifically focused on the evaluation of the performance of the rock mass of a tunnel affected by fire. Smith and Pells [7] used real fire to register substantial explosive spalling events at relatively low temperatures (little more than the boiling point of water) on sandstone tunnels in Australia. Moreover, these authors observed a decrease in uniaxial compression strength and elastic modulus in sandstone samples when using an electrical furnace.…”

Section: Introductionmentioning

confidence: 99%

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Micro and macro-structural effects of high temperatures in Prada limestone: Key factors for future fire-intervention protocols in Tres Ponts Tunnel (Spain)

Martínez-Ibáñez

Garrido

Signes

et al. 2021

Construction and Building Materials

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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 600º 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<300º C). The influence of the cooling method appeared at intermediate temperatures of 300-400º C and open porosity, P and S-wave velocities, and elastic modulus show greater variation for water-cooled samples. A temperature of 500º 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 500º 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 600º 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.

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Section: Heating and Cooling Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Micro and macro-structural effects of high temperatures in Prada limestone: Key factors for future fire-intervention protocols in Tres Ponts Tunnel (Spain)

Martínez-Ibáñez

Garrido

Signes

et al. 2021

Construction and Building Materials

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“…In recent years, the effect of temperature on rock fracture has been a concern. There are many application fields, such as the development and utilization of geothermal resources (Ogino et al, 1999;Zhao et al, 2011;Rickard, 2019), excavations of storage sites of high radioactive nuclear waste underground (Hudson et al, 2001;Rutqvist et al, 2005;Emirov et al, 2013;Wang et al, 2015), geothermal reservoirs (Pearson et al, 1983;Ghassemi et al, 2007), oil production and storage (Shafiei and Dusseault, 2013) and so on (Smith and Pells, 2008;Vasconcelos et al, 2008;Ozguven and Ozcelik, 2013;Tang et al, 2016). Further study indicates that fracture initial and progress induced by high temperature were…”

Section: Introductionmentioning

confidence: 99%

Effects of pre-existing fissures on surface macro-crack characteristics of granite subjected to elevated temperatures

Zhao¹

2019

Acta Geodynamica Et Geomaterialia

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In order to study thermal macro-cracks on granite surface, experiments were conducted to heat orthoclase granite samples under 25-800 °C. This paper reports a method for evaluating thermal damage of rock by indexes of thermal macro-cracks characteristics, including the width of macro-cracks, the length of macro-cracks, the density of macro-cracks and fractal analysis of macro-cracks. The major findings are as follows: (1) As treatment temperature increases from 500 °C to 800 °C, the average macro-crack width increases from 0.05 to 0.22 mm. And the average macro-crack length increases from 34.36 to 771.86 mm at 600-800 °C. In addition, the linear density is from 0.20 to 1.05 mm-1 and the surface density increases from 0.07 to 1.54 mm/mm 2 at 600-800 °C. (2) The temperature has an important influence on the thermal fracture fractal of the granite surface. As treatment temperature increases from 600 °C to 800 °C, the fractal dimension of macro-cracks changes from 0.47 to 1.43. (3) 400-500 °C is the threshold temperature of the thermal macro-cracks generated on the granite surface and the high temperature causes the unpenetrated fissures connect with each other.

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“…Applications include blast hole drilling, quarrying, deep-well drilling, cavity formation and well stimulation [6,7,5,8,9]. Fire-induced spallation of rock has also been identified as a growing concern in tunnel and mine safety [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%