Some observations concerning the microscopic and mechanical behaviour of quartzite specimens in stiff, triaxial compression tests

Hallbauer, D. K.; Wagner, H. Daniel; Cook, N.G.W.

doi:10.1016/0148-9062(73)90015-6

Cited by 360 publications

(129 citation statements)

References 5 publications

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“…Brittle failure nature of rock has been extensively investigated in the field [73][74][75][76][77][78][79][80] and five major failure regions have been shown (Figure 7). Among them, region I represent the pre-existing cracks close stage in the rock mass, which is dependent on the geometry and the density of microcracks in the rock mass.…”

Section: Brittle Failure Of Rockmentioning

confidence: 99%

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

2016

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Global energy and material consumption are expected to rise in exponential proportions during the next few decades, generating huge demands for deep earth energy (oil/gas) recovery and mineral processing. Under such circumstances, the continuation of existing methods in rock fragmentation in such applications is questionable due to the proven adverse environmental impacts associated with them. In this regard; the possibility of using more environmentally friendly options as Soundless Chemical Demolition Agents (SCDAs) play a vital role in replacing harmful conventional rock fragmentation techniques for gas; oil and mineral recovery. This study reviews up to date research on soundless cracking demolition agent (SCDA) application on rock fracturing including its limitations and strengths, possible applications in the petroleum industry and the possibility of using existing rock fragmentation models for SCDA-based rock fragmentation; also known as fracking. Though the expansive properties of SCDAs are currently used in some demolition works, the poor usage guidelines available reflect the insufficient research carried out on its material's behavior. SCDA is a cementitious powdery substance with quicklime (CaO) as its primary ingredient that expands upon contact with water; which results in a huge expansive pressure if this CaO hydration reaction occurs in a confined condition. So, the mechanism can be used for rock fragmentation by injecting the SCDA into boreholes of a rock mass; where the resulting expansive pressure is sufficient to create an effective fracture network in the confined rock mass around the borehole. This expansive pressure development, however, dependent on many factors, where formation water content creates a negative influence on this due to required greater degree of hydration under greater water contents and temperature creates a positive influence by accelerating the reaction. Having a precise understanding of the fracture propagation mechanisms when using SCDA is important due to the formation of complex fracture networks in rocks. Several models can be found in the literature based on the tangential and radial stresses acting on a rock mass surrounding an SCDA charged borehole. Those fracture models with quasi-static fracturing mechanism that occurs in Mode I type tensile failure show compatibility with SCDA fracturing mechanisms. The effect of borehole diameter, spacing and the arrangement on expansive pressure generation and corresponding fracture network generation is important in the SCDA fracturing process and effective handling of them would pave the way to creating an optimum fracture network in a targeted rock formation. SCDA has many potential applications in unconventional gas and oil recovery and in-situ mining in mineral processing. However, effective utilization of SCDA in such application needs much extensive research on the performance of SCDA with respect to its potential applications, particularly when considering unique issues arising in using SCDA in different ...

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Section: Brittle Failure Of Rockmentioning

confidence: 99%

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

2016

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“…3.2 GBM-UDEC 모델의 역학적 특성 (Fairhurst and Cook, 1966, Brace et al, 1966, Hallbauer et al, 1973, Tapponier and Brace, 1976, Fonseka et al, 1985, Martin and Chandler, 1994, Diederichs, 2003 Table 2와 Table 3은 아산편마암의 강도와 변형 특성을 보여준다. 일축압축 강도와 압열인장강도는 각각 3회의 실험결과에 대한 평 균치이며, 탄성정수는 방향별로 부착된 84개의 변형률 Table 3.…”

Section: Gbm-udec 모델의 미시변수와 거시물성의 관계unclassified

Polygonal Grain-Based Distinct Element Modelling of Mechanical Characteristics and Transverse Isotropy of Rock

Park¹,

Park²,

Ryu³

et al. 2016

Tunnel and Underground Space

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This study presents a methodology to reproduce the mechanical behavior of isotropic or transversely isotropic rock using the polygonal grain-based distinct element model. A numerical technique to monitor the evolution of micro-cracks during the simulation was developed in the present study, which enabled us to examine the contribution of tensile cracking and shear cracking to the progressive process of the failure. The numerical results demonstrated good agreement with general observations from rock specimens in terms of the behavior and the evolution of micro-cracks, suggesting the capability of the model to represent the mechanical behavior of rock. We also carried out a parametric study as a fundamental work to examine the relationships between the microscopic properties of the constituents and the macroscopic behavior of the model. Depending on the micro-properties, the model exhibited a variety of responses to the external load in terms of the strength and deformation characteristics. In addition, a numerical technique to reproduce the transversely isotropic rock was suggested and applied to Asan gneiss from Korea. The behavior of the numerical model was in good agreement with the results obtained in the laboratory-scale experiments of the rock.

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“…Micromechanical observations (Hallbauer et al, 1973;Olsson and Peng, 1976;Kranz, 1983) indicate that fracture initiation and fracture growth in brittle rock are to a large extent influenced by the presence of di¤erent types of defects that introduce a heterogeneity in the stress distribution. These defects include matrix and grain inhomogeneities, pre-existing cracks, strings of grain boundary cavities, interfaces between mineral grains with di¤erent elastic properties and similar heterogeneities and discontinuities.…”

Section: Flaw Modelmentioning

confidence: 99%

Implementation of a Flaw Model to the Fracturing Around a Vertical Shaft

Steen

Vervoort

Napier

et al. 2003

Rock Mechanics and Rock Engineering

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SummaryThis paper investigates whether a micromechanical model developed to investigate the relation between the basic failure processes at grain-scale and the macroscopic failure pattern can be applied to model the fracturing around large-scale excavations. The simulated fracture pattern around a vertical shaft is compared to the fracturing around a shaft at a depth of 3400 m. The simulations suggest that wedge-shaped zones, called dog-ears, are formed by a progressive splitting-like failure of the rock. The fractures forming these slabs nucleate in the zones subjected to the highest compressive stresses. Both shear and tensile mechanisms are responsible for the fracturing. The dog-ears deepen and widen as spalling continues.

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Some observations concerning the microscopic and mechanical behaviour of quartzite specimens in stiff, triaxial compression tests

Cited by 360 publications

References 5 publications

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review

Polygonal Grain-Based Distinct Element Modelling of Mechanical Characteristics and Transverse Isotropy of Rock

Implementation of a Flaw Model to the Fracturing Around a Vertical Shaft

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