Experimental investigations on the effects of ambient freeze-thaw cycling on dynamic properties and rock pore structure deterioration of sandstone

Li, Jielin; Kaunda, Rennie B.; Zhou, Keping

doi:10.1016/j.coldregions.2018.06.015

Cited by 192 publications

(76 citation statements)

References 24 publications

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“…is condition limited the expansion of the pores. ese results agreed with those suggested by Li et al [30] that, during the F-T cycles, mineral particles are compacted and the cohesive forces between them are gradually strengthened, which can availably offset part of the frost heave force, thus limiting pore expansion.…”

Section: Mass Loss Ratesupporting

confidence: 91%

“…ey found that concrete dynamic compressive strength increases with the increase in strain rate, and the strain rate effect of concrete becomes apparent after F-Tcycles. Li et al [30] conducted a test on the dynamic mechanical properties of sandstone samples exposed to F-T cycling and reported that, as F-T cycles increased, peak strain and apparent damage increase, but peak stress is reduced.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Water Pressure on the Mechanical Properties of Concrete after Freeze-Thaw Attack under Dynamic Triaxial Compression State

Wang

et al. 2019

Advances in Materials Science and Engineering

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This study aims at determining the effect of water pressure on the mechanical properties of concrete subjected to freeze-thaw (F-T) attack under the dynamic triaxial compression state. Two specimens were used: (1) a 100 mm × 100 mm × 400 mm prism for testing the loss of mass and relative dynamic modulus of elasticity (RDME) after F-T cycles and (2) cylinders with a diameter of 100 mm and a height of 200 mm for testing the dynamic mechanical properties of concrete. Strain rates ranged from 10−5·s−1 to 10−3·s−1, and F-T cycles ranged from 0 to 100. Three levels of water pressure (0, 5, and 10 MPa) were applied to concrete. Results showed that as the number of F-T cycles increased, the mass loss rate of the concrete specimen initially decreased and then increased, but the RDME decreased. Under 5 MPa of water pressure and at the same strain rate, the ultimate compressive strength decreased, whereas the peak strain increased with the increase in the number of F-T cycles. This result is contrary to the variation law of ultimate compressive strength and peak strain with the increase in strain rate under the same number of F-T times. With the increase in F-T cycles or water pressure, the strain sensitivity of the dynamic increase factor of ultimate compressive strength and peak strain decreased, respectively. After 100 F-T cycles, the dynamic compressive strength under all water pressure levels tended to increase as the strain rate increased, whereas the peak strain decreased gradually.

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Section: Mass Loss Ratesupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Influence of Water Pressure on the Mechanical Properties of Concrete after Freeze-Thaw Attack under Dynamic Triaxial Compression State

Wang

et al. 2019

Advances in Materials Science and Engineering

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“…e cyclic volumetric expansion and contraction accompanied by pore structure damage until the failure of limestone specimen were observed throughout freezing-thawing process [10]. e damage could decrease the rock dynamical peak stress and elastic moduli, increase rock porosity, and strengthen plasticity as reported by Zhang et al [15], Li et al [16], Ke et al [12], Walbert et al [13], and Khanlari et al [14]. For example, reductions of 20.2% and 21.5% in static and dynamic compressive strengths of sandstones after freeze-thaw treatments were found in the study [12]; the static and dynamic elastic moduli were found to be impacted the most by the frost weathering and can be used as indexes of first microcrack initiation, whereas the uniaxial compressive strength and the porosity were found to be affected the least [13].…”

Section: Introductionmentioning

confidence: 77%

“…For example, reductions of 20.2% and 21.5% in static and dynamic compressive strengths of sandstones after freeze-thaw treatments were found in the study [12]; the static and dynamic elastic moduli were found to be impacted the most by the frost weathering and can be used as indexes of first microcrack initiation, whereas the uniaxial compressive strength and the porosity were found to be affected the least [13]. Also, both micropore and macropore sizes of rocks increase after freeze-thaw cycles [16]. is is because, under the freeze-thaw damage, micropores can become interconnected with each other and thus become mesopores and macropores.…”

Section: Introductionmentioning

confidence: 81%

Microscopic Characteristics of Fractured Sandstone after Cyclic Freezing‐Thawing and Triaxial Unloading Tests

Shen

Zhu

2019

Advances in Civil Engineering

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e understanding of tunneling rock failure characteristics under unloading conditions in the cold region is critical for the proper design of rock tunneling support and mining safety operation. Given this understanding is currently limited, this study aimed to investigate the characteristics of fractured sandstone samples in the microscale after cyclic freezing-thawing and triaxial unloading tests. e samples were first subjected to different cycles of freezing and thawing, followed by the triaxial unloading test and scanning electron microscopy imaging. e peak strength and damage dilatancy stress were measured from the stress-strain curves. e microcrack characteristics (number, length, and width) were obtained through the image analysis. e results show that the decrease in peak strength and damage dilatancy stress was more significant by the first 20 freezing-thawing cycles when the pore pressure gradient is maximum compared to the later freezing-thawing cycles. e mechanical properties also significantly deteriorated when the severe freezing-thawing treatments were performed. e fracture section mainly had the morphology of honeycomb-like microstructure, stripped microstructure, and flocculent microstructure. e cracking extent was mainly influenced by the freezing-thawing rather than the triaxial unloading test, but the azimuthal angle of microcracks was significantly altered by the triaxial unloading. To properly design rock tunneling support and safe operation of mining in the cold region, both impact of cyclic freezing-thawing and the excavation operation direction should be considered.

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“…The low magnetic field nuclear magnetic resonance imaging (NMRI) techniques have been extensively employed in microstructure detections of porous media for their rapidity, efficiency and non-destructiveness [20]. In recent years, the NMRI technique have been frequently adopted to study geotechnical engineering to ascertain the porosity, the damage degree caused by freezing-thawing cycles, as well as the free water content in a frozen soil at different saturations [21][22][23][24]. However, reports on the application of NMRI method to investigate the pore structure of frozen-thawed soils in subway tunnel excavations are exceedingly rare.…”

Section: Introductionmentioning

confidence: 99%

Pore Distribution Characteristics of Thawed Residual Soils in Artificial Frozen-Wall Using NMRI and MIP Measurements

Kong

2020

Applied Sciences

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Artificial ground freezing method is widely applied in the construction of metro tunnel and significantly impact the microstructure of soils in artificial frozen-walls. To delve into the pore distribution characteristics of thawed residual soils, Nuclear Magnetic Resonance Imaging (NMRI) measurements were performed to investigate the relaxation time (T2) spectrums and T2-weighted images of saturated samples after freezing at different temperatures. The pore volume distributions were determined from T2 spectrums based on the surface relaxation coefficient ( ρ 2 ) and the pore structures were visualized by T2-weighted images. Subsequently, the pore size distribution curves from NMRI were compared and validated by mercury intrusion porosimetry (MIP) tests. According to the results, the peak areas of T2 spectrums were linearly related to freezing temperatures in a positive manner. Pore volume distribution curves of thawed soils have two peaks, which are the major peaks with diameters of 0.5–20 μm and the secondary peaks with diameters of 20–500 μm. As the freezing temperature drops, the volumes of pores with different diameters all increased. The damage degree of microstructure in thawed soils increases as the temperature drops, according to the visualized pore structure. Besides, NMRI measurements of saturated soils are more accurate to reflect the full diameter range of pores, compared to MIP method.

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Experimental investigations on the effects of ambient freeze-thaw cycling on dynamic properties and rock pore structure deterioration of sandstone

Cited by 192 publications

References 24 publications

Influence of Water Pressure on the Mechanical Properties of Concrete after Freeze-Thaw Attack under Dynamic Triaxial Compression State

Influence of Water Pressure on the Mechanical Properties of Concrete after Freeze-Thaw Attack under Dynamic Triaxial Compression State

Microscopic Characteristics of Fractured Sandstone after Cyclic Freezing‐Thawing and Triaxial Unloading Tests

Pore Distribution Characteristics of Thawed Residual Soils in Artificial Frozen-Wall Using NMRI and MIP Measurements

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