Assessing the uniaxial compressive strength of extremely hard cryptocrystalline flint

Aliyu, Mohammed Musa; Shang, Junlong; Murphy, William M.; Lawrence, James; Collier, Richard E. Ll.; Kong, Fanmeng; Zhao, Zhiye

doi:10.1016/j.ijrmms.2018.12.002

Cited by 54 publications

(15 citation statements)

References 45 publications

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“…The hardness can be used to estimate the strength (e.g., UCS) of homogeneous vein-filling minerals (Grigg, 2016). Several experimental studies have demonstrated that hardness is lineally correlated with the yield strength and UCS of brittle, crystalline materials (Aliyu et al, 2019;Hucka & Das, 1974;ISRM, 1981;Kahraman et al, 2012;Zhang et al, 2011). It is noted that the yield strength of brittle, crystalline materials is approximately equal to the uniaxial tensile strength (Zhang et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…Because the UCS values of rock-forming minerals are not available in the literature, instead, the hardness of mineral is frequently reported (Pellant, 2002). In addition, several experimental studies have demonstrated that hardness is lineally correlated with the UCS of brittle or crystalline materials (Aliyu et al, 2019;Grigg, 2016;Hucka & Das, 1974;ISRM, 1981;Kahraman et al, 2012;Zhang et al, 2011). The hardness was therefore used to estimate the UCS of the homogeneous vein-filling minerals (i.e., quartz and calcite), thus allowing the calibration of microparameters of the veins.…”

Section: 1029/2019jb019052mentioning

confidence: 99%

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Rupture Of Veined Granite In Polyaxial Compression: Insights From Three‐Dimensional Discrete Element Method Modeling

Shang

2020

JGR Solid Earth

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Granite formations have been frequently involved in subsurface energy‐related activities such as radioactive waste disposal, oil, and gas storage. This is principally because of their mechanical stability, low permeability, and high corrosion resistance. These favorable properties, however, can be compromised by the addition of mineral veins, which tend to occur ubiquitously in upper crustal rock formations. Evaluation of the impact of veins on the integrity and rupture characteristics of granite, especially under true triaxial stresses, is therefore important yet currently underemphasized. This study examines the rupture of veined granite in polyaxial compression via a discrete element method model. In the model with soft veins, the rupture is localized along the fabricated inclined veins (45° relative to the horizontal with strike running in the σ2 direction) under low confining stresses (σ2 < 67 MPa); in contrast, a combined rupture of veins and granite matrix is observed when σ2 is increased to 141.6 MPa. Shear sliding along the inclined veins is revealed by examining the displacement field. Shear‐induced volumetric dilation is suspected in the soft‐veined models in relatively low confining stresses (σ2 < 67 MPa) with sliding and dilation behavior apparently suppressed at σ2 = 141.6 MPa. Hard veins impede local rupture, resulting in conjugate shear bands. The well‐recognized σ2 effect is observed for the hard‐veined models, while no pronounced σ2 effect is noticed for the soft‐veined models. This study also reveals that vein thickness has a negligible impact on rupture characteristics, which is however profoundly affected by vein orientation.

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Section: Discussionmentioning

confidence: 99%

Section: 1029/2019jb019052mentioning

confidence: 99%

Rupture Of Veined Granite In Polyaxial Compression: Insights From Three‐Dimensional Discrete Element Method Modeling

Shang

2020

JGR Solid Earth

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“…The accurate assessment of uniaxial compressive strength (UCS) is fundamental to rock mass classification and rock engineering design [1][2][3][4][5]. The conventional tests for UCS, however, have some shortcomings in that they are time-consuming and expensive and use restricted sampling.…”

Section: Introductionmentioning

confidence: 99%

A hybrid modelling approach for prediction of UCS of rock materials

Xue¹,

Wei²

2020

Comptes Rendus. Mécanique

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It is necessary to make an accurate assessment of uniaxial compressive strength (UCS) for rock mass classification and rock engineering design. However, there are many shortcomings in the conventional tests for UCS of rocks. The aim of this study is to present a hybrid model by integrating the genetic algorithm (GA) into the least-squares support vector machine (LSSVM) to predict the UCS of rock materials. The GA technique was utilized to improve the forecasting accuracy of the proposed LSSVM. To develop the proposed hybrid GA-LSSVM model, four main factors including the block punch index, point load strength, Schmidt rebound hardness and ultrasonic P-wave velocity were considered as input variables, while the UCS of rock materials was the output. A comparison was conducted among the proposed GA-LSSVM, the adaptive neurofuzzy inference system, the fuzzy inference system, the artificial neural network and the statistical method in accordance with three statistical indexes. The results of the comparisons show that the developed GA-LSSVM model has great potential to accurately estimate the UCS of rock materials.

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“…The static rock elastic moduli are used to determine the formation strength parameters (UCS, friction angle, tensile strength), in situ stresses magnitudes, well completion design, reservoir subsidence modelling, borehole stability, wellbore breakouts characterization, fracture pressure prediction, anisotropy parameters and building a geomechanical model [11,15,17,18,35,36]. Even though it should be mentioned that for some rocks like flint [2], shear velocity showed no or poor correlation with their mechanical properties like UCS.…”

Section: Introductionmentioning

confidence: 99%

“…It should be highlighted that the shear velocity may also increases or decreases like the compressional velocity provided that shear weakening or shear strengthening take place, according to Eqs. (1) and (2).…”

Section: Introductionmentioning

confidence: 99%

An experimental investigation of dynamic elastic moduli and acoustic velocities in heterogeneous carbonate oil reservoirs

Shakouri¹,

Farzay²,

Masihi

et al. 2019

SN Appl. Sci.

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One of the most common methods for determining elastic moduli of rocks is the acoustic velocity log. The elastic moduli of reservoir rocks are widely used in geomechanical modeling, borehole stability analysis, and hydraulic fracture design. In the carbonate reservoirs, the effect of the fluid type on the dynamic elastic modulus under high pressure conditions have rarely been investigated. Carbonate oil reservoirs are known for their heterogeneity and anisotropic nature. Therefore, it is a challenge to find a reliable correlation between the acoustic velocity and rock/fluid properties. In this paper, the acoustic velocities of several carbonate samples with a wide range of porosity and permeability from different oil reservoirs were measured under different confining and axial stresses. Our study shows that wettability of rock samples plays an important role in the acoustic velocities, particularly in tight pores. In addition, an increase in compressional velocity after saturation was reported. In order to fully understand the effect of fluid type, a new parameter [relative change of shear modulus (RCS)] is defined. Experimental results shows that strong water wet samples have higher RCS values rather than oil wet samples which means that the wettability of the carbonate rocks is one of the main important factors in dynamic elastic modulus.

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Assessing the uniaxial compressive strength of extremely hard cryptocrystalline flint

Cited by 54 publications

References 45 publications

Rupture Of Veined Granite In Polyaxial Compression: Insights From Three‐Dimensional Discrete Element Method Modeling

Rupture Of Veined Granite In Polyaxial Compression: Insights From Three‐Dimensional Discrete Element Method Modeling

A hybrid modelling approach for prediction of UCS of rock materials

An experimental investigation of dynamic elastic moduli and acoustic velocities in heterogeneous carbonate oil reservoirs

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