scholarly journals Estimating the Effect of Fractal Dimension on Representative Elementary Volume of Randomly Distributed Rock Fracture Networks

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Jing Zhang ◽  
Liyuan Yu ◽  
Hongwen Jing ◽  
Richeng Liu
Keyword(s):  
Fractal Dimension ◽  
Functional Relationship ◽  
Rock Fracture ◽  
Representative Elementary Volume ◽  
Width Ratio ◽  
Elementary Volume ◽  
Equivalent Permeability ◽  
Length Width ◽  
Rock Fracture Networks

The effect of fractal dimension (Df) on the determination of representative elementary volume (REV) was investigated through numerical experimentations, in which a new method was adopted to extract submodels that have different length-width ratios from original discrete facture networks (DFNs). Fluid flow in 1610 DFNs with different geometric characteristics of fractures and length-width ratios was simulated, and the equivalent permeability was calculated. The results show that the average equivalent permeability (KREV) at the REV size for DFNs increases with the increase in Df. The KREV shows a downward trend with increasing length-width ratio of the submodel. A strong exponent functional relationship is found between the REV size and Df. The REV size decreases with increasing Df. With the increment of the length-width ratio of submodels, the REV size shows a decreasing trend. The effects of length-width ratio and Df on the REV size can be negligible when Df≥1.5, but are significant when Df<1.5.

scholarly journals Determination of representative elementary volume (REV) for jointed rock masses exhibiting scale-dependent behavior: A numerical investigation

2021 ◽  
Author(s):  
Mehmet Sari
Keyword(s):  
Jointed Rock ◽  
Representative Elementary Volume ◽  
Elementary Volume ◽  
Rock Masses ◽  
Continuum Approach ◽  
Joint Spacing ◽  
Jointed Rock Masses ◽  
Equivalent Continuum ◽  
Equivalent Continuum Approach

Abstract Representative elementary volume (REV) is defined as the usual size of a rock mass structure beyond which its mechanical properties are homogenous and isotropic, and its behavior can be modeled using the equivalent continuum approach. Determination of REV is a complex problem in rock engineering due to its definition ambiguity and application area. This study is one of the first attempts to define a REV for jointed rock masses using the equivalent continuum approach. It is aimed to numerically search a ratio between the characteristic size of an engineering structure and pre-existing joint spacing, which are the two most important contributing elements in assessing REV. For this purpose, four hypothetical engineering cases were investigated using the RS2 (Phase2 v. 9.0) finite element (FE) analysis program. An underground circular opening with a constant diameter, an open-pit mine with varying bench heights, a single bench with a constant height, and an underground powerhouse cavern with a known dimension were executed for possible changes in the safety factor and total displacement measurements under several joint spacing values. Different cut-off REVs were calculated for FE models depending on the type of excavation and measurement method. An average REV size of 19.0, ranging between a minimum of 2 for tunnels and a maximum of 48 for slopes, was found in numerical analysis. The calculated sizes of REV were significantly larger than the range of values (5 to 10) commonly reported in the relevant geotechnical literature.

scholarly journals VARIABILITY OF SOME BROOMRAPE POPULATIONS FROM CHINA. MORPHOMETRY AND RACE IDENTIFICATION (I)

Akademos ◽  
2021 ◽  
Vol 60 (1) ◽  
pp. 42-50
Author(s):  
Maria Duca ◽  
◽  
Ana Mutu ◽  
Ina Bivol ◽  
Steliana Clapco ◽  
...  
Keyword(s):  
Inner Mongolia ◽  
Width Ratio ◽  
Seed Length ◽  
Interpopulation Variability ◽  
Pearson Coefficient ◽  
Variability Level ◽  
Length Width ◽  
Positive Correlations ◽  
Biometric Indices

The article is a synthesis of some studies on the identification of broomrape races originating from China and the determination of the level of intra- and interpopulation variability based on the morphometric parameters of the seeds. The racial status of the analyzed populations was established, also two races of broomrape were identified: race G (Ch1 from Inner Mongolia and Ch3 from HeBei) and race H (Ch2 from Inner Mongolia) using internationally recognized differential Or homosygous lines set. Comparative analyses on the morphometric characteristics of broomrape revealed significant differences in seed Length (Ch1 and Ch3 populations, race G) and Length/width ratio (Ch3 and Ch4), which is an indication of the moderate level of interpopulation variability. In the case of assess of the intrapopulation variability level, the relatively homogeneous (Ch2, Ch3 and Ch4) and relatively heterogeneous (Ch1) populations were identified. According to the coefficient of variation, the population Ch2 identified as H broomrape race has distinguished as the most homogeneous for the investigated biometric indices of the seeds. The moderate positive correlations (between Length and width seed, between seed length and L/w ratio), the strong positive correlations (between Length and L/w ratio) and also the strong negative correlations (between width and L/w ratio) were established. The results obtained through Pearson coefficient revealed the discrimination of populations by region.

scholarly journals Determining the length-width ratio of the quarry exploited under sea level to recover maximally extraction reserves

2019 ◽  
Vol 61 (1) ◽  
pp. 110-115
Author(s):  
Nguyen Tuan Thanh ◽  
Keyword(s):  
Sea Level ◽  
Surface Area ◽  
Significant Influence ◽  
Width Ratio ◽  
Size And Shape ◽  
Length Width ◽  
Mining Design

The boundary of the quarry exploited under sea level has a significant influence on mining design, especially the determination of extraction reserves. For a quarry project, with the same given exploiting depth, the size and shape on the surface of the quarry will yield different mining alternatives and extraction reserves. This paper proposed an approach for determining the length-width ratio of the quarry (with the surface area is rectangular) to achieve maximum reserves corresponding to the quarry boundary.

scholarly journals Determination of the Representative Elementary Volume for the study of sandstones and siltstones by X-Ray microtomography

2012 ◽  
Vol 15 (4) ◽  
pp. 662-670 ◽  
Author(s):  
Jaquiel Salvi Fernandes ◽  
Carlos Roberto Appoloni ◽  
Celso Peres Fernandes
Keyword(s):  
Representative Elementary Volume ◽  
Elementary Volume ◽  
X Ray

scholarly journals Determination of representative elementary volume (REV) for jointed rock masses exhibiting scale-dependent behavior: a numerical investigation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mehmet Sari
Keyword(s):  
Jointed Rock ◽  
Representative Elementary Volume ◽  
Elementary Volume ◽  
Rock Masses ◽  
Continuum Approach ◽  
Joint Spacing ◽  
Jointed Rock Masses ◽  
Equivalent Continuum ◽  
Equivalent Continuum Approach

AbstractRepresentative elementary volume (REV) is defined as the usual size of a rock mass structure beyond which its mechanical properties are homogenous and isotropic, and its behavior can be modeled using the equivalent continuum approach. Determination of REV is a complex problem in rock engineering due to its definition ambiguity and application area. This study is one of the first attempts to define a REV for jointed rock masses using the equivalent continuum approach. It is aimed to numerically search a ratio between the characteristic size of an engineering structure and pre-existing joint spacing, which are the two most important contributing elements in assessing REV. For this purpose, four hypothetical engineering cases were investigated using the RS2 (Phase2 v. 9.0) finite element (FE) analysis program. An underground circular opening with a constant diameter, an open-pit mine with varying bench heights, a single bench with a constant height, and an underground powerhouse cavern with a known dimension were executed for possible changes in the safety factor and total displacement measurements under several joint spacing values. Different cut-off REVs were calculated for FE models depending on the type of excavation and measurement method. An average REV size of 19.0, ranging between a minimum of 2 for tunnels and a maximum of 48 for slopes, was found in numerical analysis. The calculated sizes of REV were significantly larger than the range of values (5 to 10) commonly reported in the relevant geotechnical literature.

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