Experimental study on mechanical characteristics of unloaded damaged white sandstone before peak

Ren, Heng; Zhu, Yongjian; Wang, Ping; Yu, Woong‐Ryeol; Peng, Li; Zhang, Yuqun

doi:10.1007/s12517-020-05856-z

Cited by 11 publications

(7 citation statements)

References 15 publications

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“…White 17 carried out triaxial compression experiments using a testing machine and found that the deformation of coal transitions from brittle to ductile with the increase in confining pressure. Ren et al 18 conducted mechanical tests on white sandstone under different confining pressures and showed that the peak strength of the specimens is linearly related to the confining pressure. They observed that the higher the confining pressure, the higher the peak strength of the white sandstone sample.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Coal Porosity Changes before and after Triaxial Compression Shear Deformation under Different Confining Pressures

Wang

Pan

et al. 2022

ACS Omega

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It is important to explore the changes in coal pores in response to triaxial compression and shear deformation for coal mine gas drainage and efficient coalbed methane mining. To study the variation in coal pores depending on stress, first, a mechanical analysis was carried out, and then the characteristics of coal samples before and after triaxial compression were quantitatively analyzed combined with low-temperature nitrogen adsorption experiments. The compressive strength of the coal samples with a high elastic modulus is significantly greater than that of coal samples with a low elastic modulus. Sihe coal samples with a larger elastic modulus experienced higher peak stress and strain during compression than those from the Chengzhuang Mine with a smaller elastic modulus. With the exception of the coal sample from the Chengzhuang Mine with a confining pressure of 15 MPa, the peak strength and axial strain of the coal samples gradually increased with an increase in confining pressure. The larger the elastic modulus, the greater the axial strain. After triaxial compression, pores with diameters ranging from 2 to 5 nm exhibited a significant change. After the compression of coal with a high elastic modulus, the pore volume and pore specific surface area decreased with the increase in confining pressure, by 60.7 and 59.7%, respectively (compared with raw coal). The complex pore structure consisting of mesopores and macropores (>11 nm) became simpler. The volume and specific surface area of the pores of the coal samples with a low elastic modulus first increased, then decreased, and then increased again with the increase in confining pressure, and after compression, the roughness and complexity of macropores of coal samples are greater than those of micropores. The changes induced in the coal samples of the two mining areas in response to compression differ, which are related to the mechanical properties of the coal bodies.

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Section: Introductionmentioning

confidence: 99%

Characteristics of Coal Porosity Changes before and after Triaxial Compression Shear Deformation under Different Confining Pressures

Wang

Pan

et al. 2022

ACS Omega

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“…The specific steps are as follows: 1. First, Martin point out that after the rock load is loaded to 40% of the peak strength 17 , 20 , and damage is generated. Unloading tests were conducted based on peak compressive strength tests of intact white sandstone at a specific peritectic pressure (σ3 = 1 MPa), and the unloading points were determined to be before the peak and cumulative for five working conditions.…”

Section: Results and Analysismentioning

confidence: 99%

“…During this process, the internal and external energy of the rock continues to transfer and transform. The macromechanical properties of rocks are closely related to the conversion of internal energy 16 , 17 . The failure of coal and rock is actually an instability phenomenon driven by energy.…”

mentioning

confidence: 99%

Evaluation of white sandstone mechanical behaviour and the energy evolution of prepeak unloading damage

Liang

Guo

et al. 2022

Sci Rep

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Deep high-stress roadway excavation under unloading disturbance inevitably leads to damage deterioration of the surrounding rock, which poses a serious threat to its stability. To explore the energy characteristics of white sandstone damaged by peak front unloading, uniaxial compression tests were conducted on damaged rock samples. The results show that the peak strength and modulus of elasticity of the rock sample gradually decrease with increasing damage degrees. The external work input energy, releasable elastic strain energy and dissipation energy all decreased with increasing damage. Damage evolution curves and equations of the rock samples were obtained based on the damage instantiation model established by the principle of energy dissipation and release. The effects of unloading damage on the fracture characteristics of the rock samples were analysed from both macro and microscopic viewpoints, and the results showed that a micro fracture in the rock is transformed from brittle–ductile damage, while macroscopic damage occurs in the form of a "shear"-"splitting"-"mixed shear-splitting" damage process. This paper has certain research and reference value for understanding the damage evolution characteristics of rocks with peak front unloading damage.

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“…4 ). Martin points out that after the rock load is loaded to 40% of the peak strength 20 , 21 , and damage is generated. In Fig.…”

Section: Methodsmentioning

confidence: 99%

Experimental study on uniaxial creep characteristics of sandstone with pre-peak unloading damage

Liang

Zhang

et al. 2022

Sci Rep

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Deep resource extraction has been affected by the complex geological environment of "three highs and one disturbance" for a long time. The surrounding rocks experience strong unloading stress disturbance during the underground resource extraction. The creep characteristics of the perimeter rocks are of great theoretical and practical value. Firstly, the triaxial pre-peak loading and unloading tests on the prepared samples are conducted on the intact rock samples using the TAW-200 rock mechanics test system. Then the rock samples with different degrees of pre-peak unloading damage were prepared under the condition of pre-peak yield. Finally, the uniaxial creep tests were carried out to study the uniaxial creep mechanical properties. The results show that the wave velocities of the damaged rock samples are reduced to different degrees compared with those of the intact rock samples, the creep of the pre-peak unloading damaged rock has a time-dependent damage effect, and the study results are similar to those of the conventional uniaxial creep test of the white sandstone. The instantaneous strain at all stress levels of the damaged rock samples increased gradually with the stress level, which is consistent with the non-linear functional relationship; Based on the time-dependent damage effect, the two-parameter Weibull distribution function was introduced into the West Plains viscoelasticity model, and a creep damage model for white sandstone was proposed. The improved Nishihara model can simulate the uniaxial creep characteristics of each damaged rock sample at various stress levels.

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Experimental study on mechanical characteristics of unloaded damaged white sandstone before peak

Cited by 11 publications

References 15 publications

Characteristics of Coal Porosity Changes before and after Triaxial Compression Shear Deformation under Different Confining Pressures

Characteristics of Coal Porosity Changes before and after Triaxial Compression Shear Deformation under Different Confining Pressures

Evaluation of white sandstone mechanical behaviour and the energy evolution of prepeak unloading damage

Experimental study on uniaxial creep characteristics of sandstone with pre-peak unloading damage

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