Class I and Class II Rocks: Implication of Self-sustaining Fracturing in Brittle Compression

Akinbinu, Victor Abioye

doi:10.1007/s10706-016-0011-0

Cited by 17 publications

(5 citation statements)

References 7 publications

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“…How the postfailure moduli were estimated from the stress-strain curves has been described elsewhere [12]. The characteristic behaviour of Class I and Class II rocks and their response under axial loading condition has been described by Akinbinu [13].…”

Section: Methodsmentioning

confidence: 99%

Is there A Relationship between Volumetric Quantities and Volumetric Strain Curves?

2018

AMMS

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The aim of this work is to show whether or not a relationship exists between the different volumetric strain quantities and to assess also whether the volumetric quantities are related to the different types of volumetric strain curves under failure-deformation process of hard brittle rocks. Tests were conducted to determine the complete stress-strain curves of different 83 rocks types under uniaxial compression using a closed loop servocontrolled testing system. The rocks failure-deformation behaviours curves were characterized and coordinated into groups of three different types of volumetric strain curves. The volumetric strain quantities were estimated which include, the elastic volumetric strain, slope of the normalised stressvolumetric strain curves and the maximum total volumetric strain. These volumetric strain quantities were compared with each other. The result show that the volumetric strains quantities are related by power form law. The volumetric strain quantities were also compared for each group of the three types of volumetric curves. It was established that there is connection between the volumetric strains quantities and the types of the volumetric strains curves. The relationship show a power form law and the curves become more concave from type one to type two and type three volumetric strain curves respectively.

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Section: Methodsmentioning

confidence: 99%

Is there A Relationship between Volumetric Quantities and Volumetric Strain Curves?

2018

AMMS

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“…Amongst the above ten brittleness indexes, only B1-B4 considered the Class I and Class II behaviors of rocks. Moreover, Class II behavior of rock is very likely to occur for triaxial compressive tests with high confining pressures and very stiff testing machines (Akinbinu, 2016). Thus, this paper focuses to study the relationship between the crack initiation stress and the brittleness indexes of B1-B4.…”

Section: ( ) ( )mentioning

confidence: 99%

“…Hajiabdolmajid and Kaiser (2003) considered the rock brittle failure as a time-and size-dependent process and proposed a train-dependent brittleness index. However, rock behaviors are classified into Class I or Class II based on the characteristic shape of their post-peak curve (Akinbinu, 2016). The brittleness index should consider the difference between Class I and Class II behaviors (Tarasov and Potvin, 2013) Rybacki et al (2016) proposed to use the mineral composites and percentage to predict the brittleness of shale.…”

Section: Introductionmentioning

confidence: 99%

“…Jiang et al (2020) collected uniaxial compression test data for igneous, metamorphic, and sedimentary rocks and found that the brittleness index can be expressed as a 2-parameter power function of CIS ratio (i.e., the ratio of crack initiation ratio to uniaxial compression strength). However, natural rock is normally in a triaxial stress state and the confining pressure significantly affects the rock mechanical behaviors (Akinbinu, 2016). The relationship between brittleness and crack initiation of granite based on triaxial compressive tests has never been fully understood.…”

Section: Introductionmentioning

confidence: 99%

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Investigating the Relationship between the Brittleness Index and Crack Initiation Stress for the Granite under Triaxial Compression

Guo

Zhang

et al. 2020

Lat. Am. j. solids struct.

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“…Consequently, the deformation process will result to explosive failure at peak load. The use of constant circumferential control mode as feedback signal does not guaranteed achieving post peak state for brittle Class II rocks because of their self-sustaining fracturing behaviour after peak load [5,6,7].Therefore it is practically difficult to achieve post peak failure stress strain curves for the Class II rocks under brittle uniaxial compression process [8].…”

Section: Introduction and Literature Reviewmentioning

confidence: 99%

A stochastic predictive model for Class II rocks post peak modulus

Akinbinu

2021

Preprint

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The post peak modulus of hard brittle Class II rocks are the least studied geo-mechanical properties of rocks. This is because of the difficulty associated with its determination. The Brazilian tensile strength, pre-failure mechanical properties, ultra-sonic pulse velocity and the mineralogical properties of the rocks were determined. The post peak moduli were determined under brittle uniaxial compression process. Predictive equations were developed for the estimation of the post peak modulus using backward multivariate and stochastic analysis of the determined rocks properties. The result of analysis show that the post peak modulus depends on the Poisson’s ratio and the quartz content of rocks. As the values of duo increases the magnitude of the post peak modulus decreases. Therefore, maximum possible magnitude of post peak modulus will be for mafic rocks with zero quartz content and low value of Poisson’s ratio. While low magnitude of post peak modulus will be for felsic rocks of high proportion of quartz content and high Poisson’s ratio. The backward multivariate analysis has a coefficient of correlation of 0.903 while the correlation coefficient was improved to 0.999 by stochastically modelling the relationship using normal distribution probability function for Poisson’s ratio and exponential distribution function for quartz content. The Mean Absolute Percentage Error (MAPE) was used as performance indicator to assess the predictive performance of the models. The stochastic model shows excellent performance with MAPE of 0.5% while the backward multivariate statistics model has MAPE of 0.9%. Both the backward multivariate and stochastic models are excellent prediction models.

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Class I and Class II Rocks: Implication of Self-sustaining Fracturing in Brittle Compression

Cited by 17 publications

References 7 publications

Is there A Relationship between Volumetric Quantities and Volumetric Strain Curves?

Is there A Relationship between Volumetric Quantities and Volumetric Strain Curves?

Investigating the Relationship between the Brittleness Index and Crack Initiation Stress for the Granite under Triaxial Compression

A stochastic predictive model for Class II rocks post peak modulus

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