Effect of the intermediate principal stress on 3-D crack growth

Wang, Hongyu; Dyskin, Arcady; Pasternak, Elena; Dight, Phil; Sarmadivaleh, Mohammad

doi:10.1016/j.engfracmech.2018.10.024

Cited by 46 publications

(11 citation statements)

References 26 publications

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“…In the first stage, as the surface of the open crack might not be smooth, the sharp points might break when subject to ultrasonic vibration [31]. The axial strain reduces because of the generation of breakage accompanied by the crack closure.…”

Section: Resultsmentioning

confidence: 99%

Experimental and numerical investigation of the fatigue behaviour and crack evolution mechanism of granite under ultra-high-frequency loading

et al. 2020

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Assisted ultrasonic vibration technology has received great interest in the past few years for petroleum and mining engineering related to hard rock breaking. Understanding the fatigue behaviour and damage characteristics of rock subject to ultra-high-frequency loading is vital for its application. In this research, we conducted ultrasonic vibration breaking rock experiments combined with an ultra-dynamic data receiver and strain gauges to monitor the development of strain in real time. The experimental results show that the strain curve is U-shaped, and it can be divided into three stages: the strain first decreases, then remains steady (with light fluctuations) and finally increases. The sample first underwent compressive deformation, and no rupture occurred. As the vibration continued, the compressive deformation decreased with the initiation and propagation of cracks, and fragmentation occurred. To elucidate the crack evolution mechanism of the granite specimens, numerical simulations were performed using particle flow code in two dimensions (PFC2D), and an improved fatigue damage model based on the flat-joint contact model was proposed. The numerical results indicate that this model can effectively reproduce the fatigue characteristics of hard brittle rocks under ultrasonic vibration. By analysing the stress and strain fields and cracking process, the crack evolution mechanism in the brittle hard rock under ultra-high-frequency loading is revealed. These experimental and numerical results are expected to improve the understanding of the fragmentation mechanism of rock under assisted ultrasonic vibration.

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Section: Resultsmentioning

confidence: 99%

Experimental and numerical investigation of the fatigue behaviour and crack evolution mechanism of granite under ultra-high-frequency loading

et al. 2020

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“…62 The initial cracks in the actual rock were open, which could influence the system response and deformation behavior of the rock samples under ultrasonic vibration. 23,63 It was difficult to faithfully replicate the features of the cracks in the FJM. It would be interesting to simulate a more realistic behavior of cracks, and this would constitute our future work.…”

Section: Resultsmentioning

confidence: 99%

“…However, research on rock fragmentation mechanism has been limited because of the difficulty in measuring microcracks in real time during high‐frequency vibration laboratory tests 20 . With the rapid development of computer technology and advanced numerical techniques, computational simulations help us overcome this limitation and determine the characterization of crack initiation and growth in more detail 21‐27 . In recent years, the DEM has received considerable attention for its use in modeling the dynamic process of rock failure owing to its three advantages 28‐31 .…”

Section: Introductionmentioning

confidence: 99%

“…20 With the rapid development of computer technology and advanced numerical techniques, computational simulations help us overcome this limitation and determine the characterization of crack initiation and growth in more detail. [21][22][23][24][25][26][27] In recent years, the DEM has received considerable attention for its use in modeling the dynamic process of rock failure owing to its three advantages. [28][29][30][31] Firstly, considering its micromechanical foundation, the DEM is a useful simulation tool for understanding the dynamic mechanism of rock materials at a microscale directly.…”

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Discrete element simulation for investigating fragmentation mechanism of hard rock under ultrasonic vibration loading

Tang

Zhao

Zhou

et al. 2020

Energy Science & Engineering

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With the gradual depletion of shallow resources, the energy exploration depth has been increasing and condition becomes complex. 1 Consequently, the explorations face increasingly harder rocks with higher strengths. Breaking hard rock rapidly in petroleum and mineral exploration is a popular and significant topic. 2-6 However, the current technologies cannot meet the demands of quick drilling. It is necessary to develop a more efficient technology for hard rock exploration. To achieve this goal, the assisted ultrasonic vibration technique (ultra-high-frequency cyclic loading), combined with the traditional drilling method, was first introduced by researchers at Aberdeen University. 7 To implement this technology more effectively, studies were conducted on rock-breaking characteristics under ultrasonic vibrations and optimization of the vibration parameters. The studies conducted by Wiercigroch et al 8 showed that the high-frequency axial vibration significantly enhanced the breaking rates compared to the traditional method. Subsequently, uniaxial compressive strength experiments were conducted on fine granite by Yin et al 9 to demonstrate that there exists a static force threshold for this technology. They found that the optimal value range of static loading was 200-300 N. An

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“…Wang et al 30 proposed a “frictional sliding mechanism” for layered rocks attempting to explain the deformation memory effect in low‐stress condition. It is well known that rocks are typical materials which contain a number of pre‐existing cracks or interlayer boundaries and they are three‐dimensional in nature, 31‐34 and they are served as “sliding planes” in compression. Under loading, these planes will slide when the shear stresses exceed their sliding criterion

σ_{sl}

.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of deformation memory effect of rock materials in low‐stress condition using discrete element method

Tang

Zhou

Zhao

2020

Energy Science & Engineering

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The slip behavior of the pre‐existing sliding planes (eg, cracks or inter‐grain boundaries) in rocks is a natural candidate for a mechanism of the deformation memory effect. Based on this mechanism, the deformation rate analysis (DRA) method can be used to measure in situ stress in low‐stress region. However, the traditional discrete element method (DEM) is unable to model the deformation memory effect of rock when the loading stress is lower than the crack initiation stress due to the insufficient consideration for sliding planes. The simulated stress‐strain curves obtained from previous DEM are linear in initial loading stage until cracks start to grow. In the present work, the properties of planes (ie, cohesion, frictional resistance, and relocking mechanism) are introduced into DEM contact model to simulate the deformation memory effect of rock in low‐stress region, and its feasibility was confirmed by comparing it with experimental results. It is found that there exists a suitable in situ stress range for DRA method when using it in low‐stress region, among which the inflection is precise. Four factors related to the sliding planes are discussed with parametric study to study their influence on the deformation memory effect. The results show that the cohesion and dip angle are highly related to the threshold value, while the friction coefficient and fraction of slide planes have little influence on the deformation memory effect in rocks.

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Effect of the intermediate principal stress on 3-D crack growth

Cited by 46 publications

References 26 publications

Experimental and numerical investigation of the fatigue behaviour and crack evolution mechanism of granite under ultra-high-frequency loading

Experimental and numerical investigation of the fatigue behaviour and crack evolution mechanism of granite under ultra-high-frequency loading

Discrete element simulation for investigating fragmentation mechanism of hard rock under ultrasonic vibration loading

Numerical simulation of deformation memory effect of rock materials in low‐stress condition using discrete element method

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