Experimental Study on Mechanical Properties, Acoustic Emission Energies and Failure Modes of Pre-cracked Rock Materials under Uniaxial Compression

Li, Shujian; Zhang, Dongming; Bai, Xin; Zhang, Xianmeng; Chu, Yapei; Guo, Ke

doi:10.1007/s00024-019-02201-8

Cited by 31 publications

(9 citation statements)

References 37 publications

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“…In the past decades, extensive experiments have been performed on the strength reduction and failure characteristics of rock by compressive tests of the precracked specimens [1,3,[8][9][10]. Yang et al [11][12][13] carried out a series of uniaxial and triaxial compression tests of precracked sandstone specimens.…”

Section: Introductionmentioning

confidence: 99%

“…The crack propagation behavior of the rock-like specimens with the filled and unfilled crack was investigated. Li et al [9] made sandstone specimens with a 1 mm thickness pre-crack and employed an acoustic emission (AE) system to investigate the failure characteristics during uniaxial compression tests. Although many experiments have been conducted on precracked rock failure, most of them concerned more about the crack patterns and failure characteristics.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation and Numerical Simulation on the Crack Initiation and Propagation of Rock With Pre-Existing Cracks

Guo

et al. 2020

IEEE Access

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Rock mass behavior is determined not only by the properties of the rock matrix but also mostly by the pre-existing cracks in the rock mass. Before the overall failure of rock, the crack initiation and propagation around the tip of pre-existing cracks (i.e., pre-crack) will occur and contribute to rock failure. In this paper, the deep granite from a gold mine is taken and made to specimens with the pre-crack of 0.3 mm thickness. Uniaxial compression tests are carried out on the pre-cracked specimens. The acoustic emission (AE) sensors and digital image correlation (DIC) system are employed to record the failure characteristics of the specimens. The extended finite element method (XFEM) with the non-local stress field calculation is used to simulate the crack initiation and propagation of pre-cracks. The crack patterns, opening and shearing displacements of the cracked surface, and the crack length development are obtained from numerical simulations. Finally, the effects of friction of crack surface on the crack pattern and crack propagation are investigated and discussed. It has been found that, for pre-cracked specimens, crack initiation and propagation will occur when the stress is much smaller than the rock compressive strength. And in the range of pre-crack angle 30-60°, the larger the pre-crack angle is, the larger the compressive strength is. The crack patterns from numerical simulations have a good agreement with those from experimented DIC results. Moreover, the order of crack propagation speed is consistent with the order of the compressive strength. The crack pattern and crack propagation are affected by the friction coefficient of the cracked surface.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Investigation and Numerical Simulation on the Crack Initiation and Propagation of Rock With Pre-Existing Cracks

Guo

et al. 2020

IEEE Access

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“…Among them, the flaw obliquity, as one of the important factors, it is critical for the mechanical properties of rock samples and the initiation mode of cracks. 13–18 In the aspect of crack growth path, with the increase of flaw inclination, the crack position of wing crack is gradually far away from the flaw. 13 Combined with the numerical simulation of discrete element software EDEM and experimental results, it is found that when the angle between the rock flaw and the horizontal direction is more than 60°, the failure of the specimen is more affected by the secondary crack; when the angle is about 45°, the wing crack and the secondary crack can commonly expand.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical study on crack propagation and coalescence in rock-like materials under compression

Bai

Chen

et al. 2021

The Journal of Strain Analysis for Engineering Design

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The discontinuous crack surface in a rock affects the stability of the whole rock system. The experiments in this paper were carried out by prefabricating rock-like specimens with different types of flaws, then the specimens were tested under uniaxial compression. Moreover, based on the theory of particle flow, PFC2D software was used for numerical simulation, and the comparative analysis of the experimental and simulative results was carried out to obtain the crack initiation sequence, propagation phenomenon, and failure mode of rock specimens with different flaw types. The results indicated that the wing crack started at the tip of flaw and the form of crack assumed split failure, followed by shear failure caused by the secondary crack. The tensile failure degree decreases and the influence of shear failure increases with the increase of flaw angle. The wing crack and secondary initiation stress value is 35%–55% and 85%–95% of the peak stress value. Crack coalescence appeared in adjacent flaws of rock-like specimens with multiple parallel single flaws, single-cross flaws and double-cross flaws, and the coalescence phenomenon always occurs when the stress peak value is reached. With the number of flaws increasing, the splitting failure of rock-like specimens became more and more serious, the splitting failure of double cross-flaw specimen is the most serious. As for the specimen with single-cross flaw, the wing crack would be produced at the tip of the flaw with larger obliquity. The results of this paper may offer certain reference value for the study on the mechanism of rock crack.

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“…Lin et al derived the relationship between the crack initiation angle of the open flaw tip and the dip angle of the prefabricated flaw under compression conditions [20]. Niu identified the change from microcracking to macrocracking using the acoustic emission system in the uniaxial compression tests [21,22]. Zhao et al analyzed the influence of the flaw dip angle and the filling material on the crack initiation stress and the peak strength [23,24].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Mechanical Properties of Prefabricated Single‐Cracked Red Sandstone under Uniaxial Compression

Yuan

Fu²,

Wang

et al. 2020

Advances in Civil Engineering

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This paper aims at the phenomenon of the fractured rock column in underground engineering which is prone to collapse when subjected to ground pressure. Uniaxial compression test and particle flow code (PFC2D) are used to analyze the influence of crack dip angle on the mechanical properties, crack propagation, and the failure mode of red sandstone. From the results, it is observed that the stress–strain curve of the precracked red sandstone can be divided into five stages, and there is a critical stress value in the stage of accelerated crack propagation and unstable fracture of the rock sample. Further, the peak strength, maximum strain, and the elastic modulus of the precracked red sandstone increase with the increase of crack dip angle, and the ultimate failure mode of rock sample changes from the “ladder” type failure to slope uneven failure. Furthermore, from PFC2D simulation, it is found that the tensile microcracks contribute more towards the failure of rock samples than the shear cracks. The contact force chain is very weak at the places where the precracks and macroshear planes are formed. This indicates that the original contact force is weakened due to particle fracture. Therefore, the bearing capacity of the precracked rock samples decreases with the increase in load. From the simulation results, it is found that the displacement at the shear plane of the rock sample is large, and the shear dilatation occurs. With the increase in load, the specimen falls off and is ejected. This is due to the weakening of the contact force between the internal particles. Thereafter, it fractures to produce microcracks, which gradually converge, thus providing a prerequisite for the transformation of elastic strain energy into kinetic energy.

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Experimental Study on Mechanical Properties, Acoustic Emission Energies and Failure Modes of Pre-cracked Rock Materials under Uniaxial Compression

Cited by 31 publications

References 37 publications

Experimental Investigation and Numerical Simulation on the Crack Initiation and Propagation of Rock With Pre-Existing Cracks

Experimental Investigation and Numerical Simulation on the Crack Initiation and Propagation of Rock With Pre-Existing Cracks

Experimental and numerical study on crack propagation and coalescence in rock-like materials under compression

Experimental Study on Mechanical Properties of Prefabricated Single‐Cracked Red Sandstone under Uniaxial Compression

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