Upscaling of fractured rock mass properties – An example comparing Discrete Fracture Network (DFN) modeling and empirical relations based on engineering rock mass classifications

Gottron, Dominik; Henk, Andreas

doi:10.1016/j.enggeo.2021.106382

Cited by 37 publications

(13 citation statements)

References 40 publications

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“…The RQD is also widely used in rock mass classification systems; combined with the Rock Mass Rating (RMR) (Bieniawski 1989) and the Q-system (Barton et al 1974), the ratio of (RQD/Jn) represents the block size, were Jn is the number of joint set. However, the limitations of this ratio in estimating block size was demonstrated by Bieniawiski (Huang et al 2013), Edelbro (Aksoy et al 2012), Grenon and Hadjigeorgiou (Grenon et Hadjigeorgiou 2008), Palmström (Azarafza et al 2020), and Pells (Gottron et Henk 2021). Thus, several methods for determining the average volume of rock blocks formed by orthogonal joint sets have been developed, using the average spacing between all joints in a rock mass, which is assumed equal to the product of the average spacing values of all the joint sets.…”

Section: Review Of Analytical Equationsmentioning

confidence: 99%

Advancements in rock block volume calculation by analytical method for geological engineering applications

Koulibaly

Shahbazi

Saeidi

et al. 2023

Preprint

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The shape, the volume, and the distribution of the rock blocks represent important geomechanical factors of a rock mass behavior in engineering works. Several methods have been developed for estimating these parameters, including numerical models, as well as analytical and empirical methods. However, their determination in actual in-situ conditions can be quite challenging. The existing analytical methods show limitations in determining the in-situ rock blocks volume. Numerical models provide more reliable estimates of these parameters, but they are not accessible to all, and they require a good working knowledge. Increasing the accuracy of existing analytical methods, or developing more reliable and accessible methods, are more realistic approaches to obtain better estimates of rock block volumes. This paper presents a new method to obtain more accurate estimates of in-situ rock block volume. The method is developed for rock a mass consisting of three persistent joint sets, each set having constant spacing and orientation values. It is based on vector products to obtain exact block volumes, an improvement as compared to previous methods. The volumes of the rock blocks are calculated through the multiplication of the blocks’ edge vector. The results of the developed equation are validated with the output of numerical simulations using 3DEC version 7.0 software, and the results indicate that the developed method makes it possible to determine in-situ rock block volume more reliably than the existing methods.

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Section: Review Of Analytical Equationsmentioning

confidence: 99%

Advancements in rock block volume calculation by analytical method for geological engineering applications

Koulibaly

Shahbazi

Saeidi

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…The Fisher distribution is defined by the probability density function (Gottron and Henk, 2021): where κ is the distribution parameter, i.e., the concentration, and ϕ ' is the angle of the deviation from the mean pole. This distribution is unimodal and symmetric about the φ ' axis.…”

Section: Geometric Characteristics Of Fracturesmentioning

confidence: 99%

“…The stochastic method uses the statistical results to describe the fracture network. There is no exact correspondence between individual fractures in reality, but in a representative body, the overall properties of the fracture network are the same as the real situation (Li et al, 2016;Gottron and Henk, 2021). The DFN model usually consists of three models: a distribution model, a dimensional model, and a spatial distribution model (Dowd et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…The normal vector is usually used to describe the strike and dip angle of the fractures. The probability density functions mainly include the Fisher distribution, Bingham distribution, binary normal distribution, and empirical probability distribution (Gottron and Henk, 2021). In practical applications, the Fisher distribution is the model that is most commonly used to describe the fracture direction.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fracture Characteristics and Reservoir Inhomogeneity Prediction of the Gaoyuzhuang Formation in the Xiong’an New Area: Insights From a 3D Discrete Fracture Network Model

Yue

Wang

et al. 2022

Front. Earth Sci.

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The Xiong’an new area in northern China is rich in geothermal resources. The Gaoyuzhuang Formation in the Proterozoic Jixian system is an important recently discovered geothermal reservoir. The Gaoyuzhuang reservoir has been affected by multiple stages of tectonic movement. The fractures are very well developed, resulting in strong heterogeneity in the reservoir’s porosity and permeability. Few studies have been conducted on the fractures and heterogeneity of the Gaoyuzhuang reservoir. In this study, interpretation of data from image logs was used to summarize the characteristics of the fractures, including the fractures’ strikes, dips, and lengths. The permeability distribution of the reservoir in the vicinity of the borehole was predicted. The hydro-thermal (TH) coupling model was used to reproduce the process of pumping tests, and the simulation results were found to be in good agreement with the field test data. In addition, the relationship between the fracture aperture and length was obtained, dmax=4.2×10−5⋅L0.5. The results of this study provide data and technical support for further reservoir research and evaluation of the geothermal resources of the Gaoyuzhuang reservoir.

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“…Sayers and den Boer (2012) used the DFN model to simulate the properties of rocks, such as permeability, and this model is also a good guide for practical engineering applications. By introducing Monte Carlo simulation techniques, various researchers have achieved better simulation results for the mechanical characteristics of fractured rock masses (Gottron and Henk, 2021). Ren et al.…”

Section: Introductionmentioning

confidence: 99%

Hydro-mechanical coupling characteristics and damage constitutive model of low-permeability granite under triaxial compression

Zheng

Wang

et al. 2022

International Journal of Damage Mechanics

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To investigate the effect of hydro-mechanical coupling characteristic in low-permeability hard rocks during the excavation of groundwater-sealed energy cavern and hydraulic engineering tunnels or chambers, triaxial compression tests were conducted on engineering granite under different confining and seepage pressures. The mechanical properties, such as the strength and deformation parameters, of granite under hydro-mechanical coupling condition were studied. The permeability of the granite under different stresses first decreases, then stabilizes, and then increases significantly until the final abrupt change, and the inflection point of the abrupt change in permeability tends to be in advance as the confining pressure increases or the seepage pressure decreases. Based on the statistical damage theory and test result, combined with the Mogi-Coulomb strength criterion, a hydro-mechanical coupling statistical damage constitutive model that considers the rock damage threshold and the initial compaction effect was proposed, and the proposed mechanical model was verified based on the test results under different confining and seepage pressures. The proposed mechanical model was further applied to predict permeability catastrophes during rock fracturing and achieves good results. This study provides a theoretical basis for the prevention and control of hydro-mechanical coupled disasters in rock engineering.

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Upscaling of fractured rock mass properties – An example comparing Discrete Fracture Network (DFN) modeling and empirical relations based on engineering rock mass classifications

Cited by 37 publications

References 40 publications

Advancements in rock block volume calculation by analytical method for geological engineering applications

Advancements in rock block volume calculation by analytical method for geological engineering applications

Fracture Characteristics and Reservoir Inhomogeneity Prediction of the Gaoyuzhuang Formation in the Xiong’an New Area: Insights From a 3D Discrete Fracture Network Model

Hydro-mechanical coupling characteristics and damage constitutive model of low-permeability granite under triaxial compression

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