Determination of thermal damage in rock specimen using intelligent techniques

Sirdesai, Nikhil; Singh, Alok Kumar; Sharma, Laxmi Kant; Singh, Rajesh; Singh, T. N.

doi:10.1016/j.enggeo.2018.03.027

Cited by 44 publications

(18 citation statements)

References 50 publications

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“…These predictions improved when using artificial neural network and adaptive neuro-fuzzy inference systems (coefficients of determination were close to 1) [40]. Such techniques and predictors were used to improve the prediction of thermal damage [41].…”

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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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: 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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“…Li et al [8] proposed to use colorimetry as a simple but effective method to assess fire damage of rocks. The hardness is found to generally weaken as the temperature applied to the rocks is gradually increased [9][10][11][12]. Similarly, with an increase in the applied temperature, the P-wave velocity showed a decreasing trend [13][14][15].…”

Section: Introductionmentioning

confidence: 94%

Comparison of Mechanical Behavior and Acoustic Emission Characteristics of Three Thermally-Damaged Rocks

Peng

Yang

2018

Energies

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High temperature treatment has a significant influence on the mechanical behavior and the associated microcracking characteristic of rocks. A good understanding of the thermal damage effects on rock behavior is helpful for design and stability evaluation of engineering structures in the geothermal field. This paper studies the mechanical behavior and the acoustic emission (AE) characteristic of three typical rocks (i.e., sedimentary, metamorphic, and igneous), with an emphasis on how the difference in rock type (i.e., porosity and mineralogical composition) affects the rock behavior in response to thermal damage. Compression tests are carried out on rock specimens which are thermally damaged and AE monitoring is conducted during the compression tests. The mechanical properties including P-wave velocity, compressive strength, and Young’s modulus for the three rocks are found to generally show a decreasing trend as the temperature applied to the rock increases. However, these mechanical properties for quartz sandstone first increase to a certain extent and then decrease as the treatment temperature increases, which is mainly attributed to the high porosity of quartz sandstone. The results obtained from stress–strain curve, failure mode, and AE characteristic also show that the failure of quartz-rich rock (i.e., quartz sandstone and granite) is more brittle when compared with that of calcite-rich rock (i.e., marble). However, the ductility is enhanced to some extent as the treatment temperature increases for all the three examined rocks. Due to high brittleness of quartz sandstone and granite, more AE activities can be detected during loading and the recorded AE activities mostly accumulate when the stress approaches the peak strength, which is quite different from the results of marble.

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“…To evaluate the performance of the fitting curves, the root mean square error (RMSE) and coefficient of determination (R 2 ) were introduced [30,91]. R 2 measures how well the association is between changes in two variables, and RMSE is used to find the sample standard deviation of the error between regressed and actual values.…”

Section: Peak Strength and Peak Axialmentioning

confidence: 99%

Mechanical Properties and Statistical Damage Constitutive Model of Rock under a Coupled Chemical-Mechanical Condition

et al. 2019

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Chemical corrosion has a significant impact on the damage evolution behavior of rock. To investigate the mechanical damage evolution process of rock under a coupled chemical-mechanical (CM) condition, an improved statistical damage constitutive model was established using the Drucker-Prager (D-P) strength criterion and two-parameter Weibull distribution. The damage variable correction coefficient and chemical damage variable which was determined by porosity were also considered in the model. Moreover, a series of conventional triaxial compressive tests were carried out to investigate the mechanical properties of sandstone specimens under the effect of chemical corrosion. The relationship between rock mechanics properties and confining pressure was also explored to determine Weibull distribution parameters, including the shape parameter m and scale parameter F0. Then, the reliability of the damage constitutive model was verified based on experimental data. The results of this study are as follows: (i) the porosity of sandstone increased and the mechanical properties degraded after chemical corrosion; (ii) the relationships among the compressive strength, the peak axial strain, and confining pressures were linear, while the relationships among the elastic modulus, the residual strength, and confining pressures were exponential functions; and (iii) the improved statistical damage constitutive model was in good agreement with the testing curves with R2>0.98. It is hoped that the study can provide an alternative method to analyze the damage constitutive behavior of rock under a coupled chemical-mechanical condition.

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Determination of thermal damage in rock specimen using intelligent techniques

Cited by 44 publications

References 50 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)

Comparison of Mechanical Behavior and Acoustic Emission Characteristics of Three Thermally-Damaged Rocks

Mechanical Properties and Statistical Damage Constitutive Model of Rock under a Coupled Chemical-Mechanical Condition

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