Failure mechanical behavior of pre-holed granite specimens after elevated temperature treatment by particle flow code

Yang, Sheng‐Qi; Tian, Wen‐Ling; Huang, Yan‐Hua

doi:10.1016/j.geothermics.2017.10.018

Cited by 104 publications

(32 citation statements)

References 31 publications

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“…For the numerical study, the parallel bond model (PBM) in PFC3D was chosen as the micromodel for the following reasons: The PBM is a basic and typical model that can transmit both forces and moments between balls . The PBM had been extensively employed in the simulation of rock material, which was successful in reproducing the mechanical behaviours of rock . In the numerical model in this study, the ball radius followed a uniform distribution that ranges from 0.65 to 0.78 mm.…”

Section: Experimental and Numerical Methodsmentioning

confidence: 99%

“…From the viewpoint of laboratory experiments, acoustic emission (AE), photographic monitoring, digital image correlation (DIC), and computed tomography (CT) scanning techniques are adopted to capture the crack evolution process in rock that contains pre‐existing flaws under compression or tension . From the view point of numerical simulation, crack initiation and coalescence process of rock is reproduced in RFPA3D, FLAC, AUTODYN, FEMDEM, NOSB‐PD, NMM, GPD, and particle flow code (PFC) …”

Section: Introductionmentioning

confidence: 99%

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Cracking process of a granite specimen that contains multiple pre‐existing holes under uniaxial compression

Huang

Yang

Tian

2019

Fatigue Fract Eng Mat Struct

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The pre‐existence of openings, which play an important role in the mechanical properties and cracking behaviours of rock, is prevalent in rock mass. The interaction among pre‐existing openings (or holes) complicates the instability problems when rock contains multiple holes. Studying the strength failure behaviour of rock that contains multiple pre‐existing holes contributes to the fundamental knowledge of the excavation and stability of underground rock engineering. In this study, first, a series of uniaxial compression tests were performed on granite specimens that contain multiple small holes to investigate the effect of the geometry of pre‐existing holes on the strength and fracture behaviours of rock. The crack initiation, propagation and coalescence process, and acoustic emission (AE) characteristics were investigated using photographic and AE monitoring. Three failure modes were identified, ie, splitting failure, stepped path failure, and planar failure modes. Second, a set of micromechanical parameters in the PFC3D model were calibrated by comparison with the experimental results of an intact granite specimen. The numerically simulated peak strength, peak strain, and failure mode of preholed specimens were consistent with the experimental results. In accordance with the numerical results, the failure modes of the preholed specimens were dependent on the bridge angle and number of holes. Last, the internal fracture characteristics of numerical specimens were revealed by analyzing the horizontal and vertical cross sections at different positions.

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Section: Experimental and Numerical Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cracking process of a granite specimen that contains multiple pre‐existing holes under uniaxial compression

Huang

Yang

Tian

2019

Fatigue Fract Eng Mat Struct

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“…e ve S ij = S e = S v = S ve e ij = e e + e v + e ve (4) where S ij is the partial stress tensor, and S e , S v and S ve are the partial stress tensors for elastic, viscous and visco-elastic bodies respectively. e ij is the partial strain tensor, and e e e v and e ve are the corresponding partial strain tensors.…”

Section: Construction Of Creep Damage Equationmentioning

confidence: 99%

“…Compared with conventional fossil fuels, for instance coal and oil, geothermal energy is one of the most abundant sources of energy, which offers great advantages in cost, reliability and environmental friendliness [1][2][3][4]. This has stimulated further investigation on the mechanical behavior of rock at high pressure and temperature.…”

Section: Introductionmentioning

confidence: 99%

Multi-Step Loading Creep Behavior of Red Sandstone after Thermal Treatments and a Creep Damage Model

Yang

Ranjith

et al. 2018

Energies

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Abstract:Triaxial compressive creep tests were conducted on red sandstones after different thermal treatments. Subsequently, the thermal influence on the axial, lateral and volumetric creep curves under various stress levels was analyzed. The results show that both the instantaneous and time-based deformation behaviors depended largely on the stress and temperature conditions. The instant axial strain increases linearly with increasing deviator stress and the instant deformation modulus decreases non-linearly with temperature. An interesting phenomenon was observed whereby the lateral creep strain had an apparent linear correlation with the axial creep strain. Furthermore, the fitting lines' slopes of lateral and axial creep strain increase gradually with the increasing deviator stress at identical temperature and first decreases and then increases as temperature is elevated. Then, on the basis of the Burgers creep model and the concept of strain energy, a creep damage model implemented in FLAC 3D (Fast Lagrangian Analysis of Continua 3D) is presented, and this model was able to describe the entire creep process completely including primary creep stage, secondary creep stage, and tertiary creep stage comparing with the experimental and theoretical results based on test data and numerical calculations. The influence of two damage parameters on creep curves and the thermal influence on creep parameters are subsequently discussed. Under the same stress level, the parameters K, G M and G K and η K of creep model decrease with temperature, while the parameter η M first augments as temperature rise to 300 • C and then decreases as temperature at above 300 • C. The higher is the temperature, the smaller the critical stress ratio (CSR).

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“…The failure patterns of specimens can provide some important information on their mechanical behaviour [24,25]. To better understand the failure mechanisms of brine-saturated sandstone specimens under conventional triaxial compression, the images of failed specimens under each confining pressure and salinity level are shown in Figure 16.…”

Section: Fracture Behaviormentioning

confidence: 99%

The Effects of NaCl Concentration and Confining Pressure on Mechanical and Acoustic Behaviors of Brine-Saturated Sandstone

et al. 2018

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Abstract:To better understand the mechanical behavior of rock with brine saturation, conventional triaxial experiments were carried out on sandstone for a range of confining pressures (0-60 MPa) and NaCl concentrations (0-30%). As the confining pressure and NaCl concentration increased, the triaxial compressive strength, crack damage threshold, Young's modulus, cohesion, and internal friction angle all increased. Real-time ultrasonic wave and acoustic emission (AE) techniques were used to obtain the relationship between acoustic behavior and stress level during the whole triaxial compression process. During the whole deformation process, the evolution of P-wave velocity and accumulated AE count could be divided into four phases. The microstructural characteristics of brine-saturated sandstone, before and after loading, indicated that the strength enhancement mechanism may be attributed to an increase in inter-particle friction resulting from salt crystallisation around the points of contact. The angle of friction increased by more than 86% at maximum NaCl concentration compared to that for distilled water. The NaCl deposition in the pore space resulted in nonlinear strength increases for the brine-saturated sandstone specimens with increasing salinity. The present study is expected to improve the knowledge of the strength and failure mechanisms of sedimentary rock in deep saline aquifers.

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Failure mechanical behavior of pre-holed granite specimens after elevated temperature treatment by particle flow code

Cited by 104 publications

References 31 publications

Cracking process of a granite specimen that contains multiple pre‐existing holes under uniaxial compression

Cracking process of a granite specimen that contains multiple pre‐existing holes under uniaxial compression

Multi-Step Loading Creep Behavior of Red Sandstone after Thermal Treatments and a Creep Damage Model

The Effects of NaCl Concentration and Confining Pressure on Mechanical and Acoustic Behaviors of Brine-Saturated Sandstone

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