Discussion of the paper “Impact of fire on Tunnels in Hawkesbury Sandstone” by Smith and Pells [Tunnelling and Underground Space Technology 23 (2008) 65–74]

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

doi:10.1016/j.tust.2008.05.001

Cited by 4 publications

(3 citation statements)

References 2 publications

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“…Moreover, these authors observed a decrease in uniaxial compression strength and elastic modulus in sandstone samples when using an electrical furnace. Conclusions on rock spalling were later confirmed in a real accident [8], and the generation of steam pressure was recognised as the main mechanism causing spalling. Studies on tunnels in igneous rocks in Sweden [9] enabled the identification of ranges of temperatures causing key variations in the mineralogical, physical, and mechanical properties of rocks.…”

Section: Introductionmentioning

confidence: 84%

“…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%

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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: Introductionmentioning

confidence: 84%

Section: Heating and Cooling Proceduresmentioning

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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“…Further exploration by Smith & Pells (2009) involved a truck crash into a 40 m high exposed batter on a highway in Sydney, Australia. The ignited vehicle was 1 m from the sandstone batter, with flames reaching 15 m from the ground.…”

Section: Introductionmentioning

confidence: 99%

Tensile strength of Hawkesbury sandstone exposed to high temperatures: considerations for exposed mine batters

Cranfield-Brooks,

Pallewela Liyanage,

Guerreri

2023

SSIM 2023: Third International Slope Stability in Mining Conference

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Infrastructure projects and mine site haul roads both often use heavy machinery transport. These high-powered machines are nearly always powered by fuel sources that are highly combustible and pose a fire risk to the surrounding rock structures. This scenario can also be seen in open pit coal mines where batters have the potential to combust spontaneously and are therefore exposed to high temperatures. This research aims to investigate the effects of exposure to high temperatures due to fires on the tensile strength of Hawkesbury sandstone by subjecting them to peak temperatures of 1,100°C -similar to the peak temperature of the hydrocarbon fire curves. The results of the Brazilian tensile strength test showed a 60% reduction in tensile strength due to high temperature exposure and less brittle characteristics when heated compared to untreated samples. The findings of this study can provide an initial understanding to slope stability assessments for fire-resilient slope design.

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Effects of tunnel fires on the mechanical behaviour of rocks in the vicinity – A review

Wasantha

Guerrieri

2021

Tunnelling and Underground Space Technology

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Discussion of the paper “Impact of fire on Tunnels in Hawkesbury Sandstone” by Smith and Pells [Tunnelling and Underground Space Technology 23 (2008) 65–74]

Cited by 4 publications

References 2 publications

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

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

Tensile strength of Hawkesbury sandstone exposed to high temperatures: considerations for exposed mine batters

Effects of tunnel fires on the mechanical behaviour of rocks in the vicinity – A review

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