Deterioration and strain energy development of sandstones under quasi-static and dynamic loading after freeze-thaw cycles

Jian, Zhang; Deng, Hongwei; Taheri, Abbas; Ke, Bo; Liu, Chuanju

doi:10.1016/j.coldregions.2019.01.007

Cited by 65 publications

(19 citation statements)

References 36 publications

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“…31 In addition, although the fractures and particles in sandstone were compressed during the increase in volumetric strain, the shear slip inside the sandstone also affected the permeability evolution under the deviator stress. Zhang et al 40 considered that there is a strong correlation between porosity and strain energies. Figures 15 and 16 show the relationship between normalized permeability (k N ) and dilatancy capacity (Δε V = ε V-1 − ε V-f ), loading-unloading rate (v), respectively.…”

Section: Permeabilit Y Evolutionmentioning

confidence: 99%

Experimental study on strain behavior and permeability evolution of sandstone under constant amplitude cyclic loading‐unloading

Liu

Zhang

et al. 2019

Energy Science & Engineering

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The coupling of in situ stress, seepage, and fracture makes the strata exhibit complex strain behavior and permeability evolution under the stress path of cyclic loading-unloading. In this study, the cyclic loading-unloading experiments of constant amplitude axial stress of sandstone under the combination of different initial confining pressures and loading-unloading rates are conducted. The experimental resultsshow that the heterogeneity of sandstone, Poisson's ratio produced by adjacent loading-unloading, and confining pressure determine the deformation characteristics of sandstone in lateral and axial directions. Sandstone can produce significant shear dilatancy at a low rate; this is because stress perturbation can activate more particle slippage and fracture structure changes. However, the fracture preferentially propagates along the end or edge of the crack with strong stress sensitivity to form a shear failure plane at high rate. The normalized permeability of sandstone decreases with an increase in the loading-unloading rate before failure. The evolution of normalized permeability is closely related to the shear slip of fracture structure and sandstone particles. For the prevention of rock engineering disasters, the high loading-unloading rate results in lower normalized permeability, which favors the prevention of gastype disasters in rocks with higher gas potential energy; however, it is not conducive to the prevention of rockburst. K E Y W O R D Sconstant amplitude cyclic loading-unloading, loading-unloading rate, normalized permeability, shear effect, volumetric strain | 453 LIU et aL.

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Section: Permeabilit Y Evolutionmentioning

confidence: 99%

Experimental study on strain behavior and permeability evolution of sandstone under constant amplitude cyclic loading‐unloading

Liu

Zhang

et al. 2019

Energy Science & Engineering

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“…But this understanding is still limited as currently most unloading rock failure studies focus on the rock failure behaviour without freezing-thawing damage [7][8][9]. e static mechanical properties and durability of rocks degraded after freezing-thawing cycles [6,[10][11][12][13][14]. e cyclic volumetric expansion and contraction accompanied by pore structure damage until the failure of limestone specimen were observed throughout freezing-thawing process [10].…”

Section: Introductionmentioning

confidence: 99%

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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“…Several scholars have discussed the evolution in the pore structure of rocks with F-T cycles using nuclear magnetic resonance (hereinafter NMR) technology. They found that repeated F-T cycles directly destroy the internal pore structure of the rock, causing the increase in porosity [ 28 , 29 , 30 , 31 ]. Moreover, X-ray computed tomography (CT) and scanning electron microscopy (SEM) observations have also confirmed remarkable changes in the microscopic pore structure of rock due to F-T action, clearly showing that micro-cracks inside the rock expand and grow significantly [ 32 , 33 , 34 ].…”

Section: Introductionmentioning

confidence: 99%

Frost Damage in Tight Sandstone: Experimental Evaluation and Interpretation of Damage Mechanisms

Ding

Jia

Zi³

et al. 2020

Materials

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Low-porosity tight rocks are widely used as building and engineering materials. The freeze–thaw cycle is a common weathering effect that damages building materials in cold climates. Tight rocks are generally supposed to be highly frost-resistant; thus, studies on frost damage in tight sandstone are rare. In this study, we investigated the deterioration in mechanical properties and changes in P-wave velocity with freeze–thaw cycles in a tight sandstone. We also studied changes to its pore structure using nuclear magnetic resonance (NMR) technology. The results demonstrate that, with increasing freeze–thaw cycles, (1) the mechanical strength (uniaxial compressive, tensile, shear strengths) exhibits a similar decreasing trend, while (2) the P-wave velocity and total pore volume do not obviously increase or decrease. (3) Nanopores account for >70% of the pores in tight sandstone but do not change greatly with freeze–thaw cycles; however, the micropore volume has a continuously increasing trend that corresponds to the decay in mechanical properties. We calculated the pressure-dependent freezing points in pores of different diameters, finding that water in nanopores (diameter <5.9 nm) remains unfrozen at –20 °C, and micropores >5.9 nm control the evolution of frost damage in tight sandstone. We suggest that pore ice grows from larger pores into smaller ones, generating excess pressure that causes frost damage in micropores and then nanopores, which is manifested in the decrease in mechanical properties.

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Deterioration and strain energy development of sandstones under quasi-static and dynamic loading after freeze-thaw cycles

Cited by 65 publications

References 36 publications

Experimental study on strain behavior and permeability evolution of sandstone under constant amplitude cyclic loading‐unloading

Experimental study on strain behavior and permeability evolution of sandstone under constant amplitude cyclic loading‐unloading

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

Frost Damage in Tight Sandstone: Experimental Evaluation and Interpretation of Damage Mechanisms

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