Mechanical properties and failure mode of sandstone specimen with a prefabricated borehole under true triaxial stress condition

Lü, Jun; Yin, Guangzhi; Zhang, Dongming; Li, Xing; Huang, Gun; Hu, Gao

doi:10.1016/j.gete.2020.100207

Cited by 28 publications

(8 citation statements)

References 51 publications

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“…Due to the long-term geological tectonics and human activities, there are often many natural fissures in the rock mass, which will degrade the mechanical properties of rock mass [1][2][3][4][5][6][7][8][9][10][11][12] and lead to engineering accidents and disasters. Therefore, the research on the mechanical behavior of fissured rocks has always been the focus of the geotechnical engineering community.…”

Section: Introductionmentioning

confidence: 99%

Discrete Element Modeling on Mechanical Behavior of Heterogeneous Rock Containing X-Shaped Fissure under Uniaxial Compression

et al. 2020

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Based on the experimental results of an intact rock specimen under uniaxial compression, particle flow code (PFC2D) was adopted to carry out a discrete element modeling (DEM) for the mechanical behavior of heterogeneous rocks containing X-shaped fissures (two intersecting symmetric single fissures) under uniaxial compression. The influences of β (the acute angle between two single fissures) and the direction angle α (the acute angle between the bisector of β and perpendicular to the loading direction) on the strength, deformation, energy, crack propagation, and ultimate failure mode were analyzed in detail. Numerical simulated results showed the following: (1) Due to the X-shaped fissures, not only the peak strength, elastic modulus, crack initiation stress, and damage stress were significantly reduced, and the reduced degree of the peak strength was obviously greater than that of the elastic modulus, but also the brittleness and energy were significantly weakened. (2) The peak strength and elastic modulus generally decreased with the increase of β and increased with the increase of α . Moreover, the change trends of crack initiation stress, damage stress, boundary energy, and total strain energy at the peak stress were consistent with the peak strength. (3) Regardless of the changes of α and β , models all firstly initiated wing cracks at the two tips of the single fissure with a larger inclination angle, and the crack initiation angle decreased with the increase of the inclination angle of the single fissure. (4) The fracture was dominated by tensile microcracks, and no microcracks were generated in a certain range of the X-shaped fissure center. The failure mode was mainly split along the axial direction, and the failure surface started from the tips of the fissure and extended to both ends of models. (5) The uniaxial compressive strength and elastic modulus increased exponentially with the increase of the homogeneity factor. When the homogeneity factor was small, the microcracks were more evenly distributed in the models; when the homogeneity factor was large, the microcracks were mainly concentrated at the tips of the fissure in the models. This study can provide some references for the correct understanding of the mechanical properties of rock masses containing X-shaped fissures.

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Section: Introductionmentioning

confidence: 99%

Discrete Element Modeling on Mechanical Behavior of Heterogeneous Rock Containing X-Shaped Fissure under Uniaxial Compression

et al. 2020

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“…It should be recognized that the element stress values in this study are obtained by numerical simulation (in the energy calculation model, the energy calculation parameters of the element in the plastic zone adopt the results derived from FLAC 3D , and adopt the energy calculation method equivalent to the elastic element, which will bring some errors, but will not change the law of energy release), and it is difficult to monitor the three-dimensional stress state of every element in the actual field to verify the correctness of the method. The next step is likely to be reflected in the laboratory or by field verification (such as the results in [ 53 ]) of the method, and seek monitoring methods to monitor the three-dimensional stress field or real-time plastic zone state.…”

Section: Discussionmentioning

confidence: 99%

The Revealed Mechanism of Rock Burst Based on an Innovative Calculation Method of Rock Mass Released Energy

Zhang

Feng

Shi

2022

IJERPH

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It is very necessary to study the mechanism of rock burst, which is related to the safe construction of many geotechnical projects. Previous studies have shown that small trigger stress will lead to large energy release, but the specific conditions that cause the release and how to quantify the energy are urgent problems to be solved. In this study, an innovative calculation method of rock mass energy release is proposed, and the calculated release energy is consistent with the monitoring results of field monitoring equipment. The revealed mechanism of rock burst reflected is that under the condition of a large-ratio pre-state stress field (mostly > 2.5), a small trigger stress field will lead to a large amount of energy release under “late butterfly shape” or “final butterfly shape” of the plastic zone. This study reveals the key factor of rock burst, which plays an important reference role for the mechanism research, subsequent monitoring and treatment method of rock burst.

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“…Due to the presence of pores in the specimen, the strength of the specimen is reduced to a certain extent, and the magnitude of the strength reduction increases with the increase of the pore size, and the strength reduction factor is defined by Equation (1). 31 The stress-strain curves of the 8 mm pore size rock specimens with pores are shown in Figure 3 by combining the load variation…”

Section: Crack and Strain Evolution Of 8 MM Diameter Samplesmentioning

confidence: 99%

Study on destabilization failure characteristics and energy evolution law of drilling holes

Wang

Kong

et al. 2023

Energy Science & Engineering

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Borehole destabilization damage is an important factors affecting gas extraction efficiency. To derive the fracture development law, strain, and energy evolution characteristics of different borehole diameters, uniaxial compression experiments were conducted on prefabricated rock specimens with different borehole diameters. The results showed that the elastic energy and dissipation energy of the specimens with different pore diameters changed with the compression process, and the energy distribution inside the specimens. The results show that as the pore size of the specimen increases, the strain area damaged by tensile fracture gradually decreases and the strain area damaged by shear fracture gradually increases, and the damage of the dominant specimen gradually evolves from tensile fracture as the dominant factor to tensile fracture and shear fracture together as the dominant factor and finally to shear fracture as the dominant factor. For the whole compression process of pore size rock specimens, the total energy curve shows a nonlinear growth trend, and the elastic energy curve shows a nonlinear growth trend before the specimen damage and a cliff‐type decrease after the specimen damage. From the perspective of energy distribution, the elastic energy storage limit of the specimen decreases with the increase of the specimen pore size, the energy distribution law inside the rock specimen with pores changes, and the total energy absorbed from the outside gradually changes to the dissipated energy, resulting in an increasing proportion of dissipated energy, indicating that the larger the pore size, the larger the plastic deformation, and the more obvious ductile damage characteristics of the specimen with pores will be shown. The research analyzes the causes of destabilization of rock samples with different hole diameters and provides some theoretical guidance for the study of gas extraction drilling stability.

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Mechanical properties and failure mode of sandstone specimen with a prefabricated borehole under true triaxial stress condition

Cited by 28 publications

References 51 publications

Discrete Element Modeling on Mechanical Behavior of Heterogeneous Rock Containing X-Shaped Fissure under Uniaxial Compression

Discrete Element Modeling on Mechanical Behavior of Heterogeneous Rock Containing X-Shaped Fissure under Uniaxial Compression

The Revealed Mechanism of Rock Burst Based on an Innovative Calculation Method of Rock Mass Released Energy

Study on destabilization failure characteristics and energy evolution law of drilling holes

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