The use of discrete fracture networks for modelling coupled geomechanical and hydrological behaviour of fractured rocks
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In this paper, the authors present a discussion of the state-of-the-art on the use of discrete fracture networks (DFNs) for modelling geometrical characteristics, geomechanical evolution and hydromechanical (HM) behaviour of natural fracture networks in rock.About:
This article is published in Computers and Geotechnics.The article was published on 2017-05-01 and is currently open access. It has received 360 citations till now.read more
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VALIDITY OF CUBIC LAW FOR FLUID FLOW IN A DEFORMABLE ROCK FRACTURE - eScholarship
Abstract: The validity of the cubic law for laminar flow of fluids through open fractures consisting of parallel planar plates has been established by others over a wide range of conditions with apertures ranging down to a minimum of 0.2 µm. The law may be given in simplified form by Q/Δh = C(2b)3, where Q is the flow rate, Δh is the difference in hydraulic head, C is a constant that depends on the flow geometry and fluid properties, and 2b is the fracture aperture. The validity of this law for flow in a closed fracture where the surfaces are in contact and the aperture is being decreased under stress has been investigated at room temperature by using homogeneous samples of granite, basalt, and marble. Tension fractures were artificially induced, and the laboratory setup used radial as well as straight flow geometries. Apertures ranged from 250 down to 4µm, which was the minimum size that could be attained under a normal stress of 20 MPa. The cubic law was found to be valid whether the fracture surfaces were held open or were being closed under stress, and the results are not dependent on rock type. Permeability was uniquely defined by fracture aperture and was independent of the stress history used in these investigations. The effects of deviations from the ideal parallel plate concept only cause an apparent reduction in flow and may be incorporated into the cubic law by replacing C by C/ƒ. The factor ƒ varied from 1.04 to 1.65 in these investigations. The model of a fracture that is being closed under normal stress is visualized as being controlled by the strength of the asperities that are in contact. These contact areas are able to withstand significant stresses while maintaining space for fluids to continue to flow as the fracture aperture decreases. The controlling factor is the magnitude of the aperture, and since flow depends on (2b)3, a slight change in aperture evidently can easily dominate any other change in the geometry of the flow field. Thus one does not see any noticeable shift in the correlations of our experimental results in passing from a condition where the fracture surfaces were held open to one where the surfaces were being closed under stress.
Estimation discontinuity spacing and trace length using scanline surveys
TL;DR: In this article, the authors present an expression which gives the degree of confidence that can be assigned to the measured mean discontinuity spacing, and a reduced form of this expression is obtained for cases where the discontinuity spacings follow the negative exponential distribution.
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Analysis of hydraulic fracturing techniques: hybrid fuzzy approaches
TL;DR: Among the five fundamental criteria for selecting and operating hydraulic fracturing, in situ stress-strain with the score weight of 0.421 is the most important selectivity criteria and hydra-jet fracturing and zipper fracturing techniques are the best and optimum techniques of hydraulic fracturing.
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Development of a 3D Hybrid Finite-Discrete Element Simulator Based on GPGPU-Parallelized Computation for Modelling Rock Fracturing Under Quasi-Static and Dynamic Loading Conditions
Daisuke Fukuda,Daisuke Fukuda,M. Mohammadnejad,M. Mohammadnejad,Hongyuan Liu,Qianbing Zhang,Jian Zhao,Sevda Dehkhoda,Sevda Dehkhoda,Andrew Chan,Jun-ichi Kodama,Yoshiaki Fujii +11 more
TL;DR: The results demonstrate that the GPGPU-parallelized 3D Y-HFDEM IDE code is a valuable and powerful numerical tool for investigating rock fracturing under quasi-static and dynamic loading conditions in rock engineering applications although very fine elements with maximum element size no bigger than the length of the fracture process zone must be used in the area where fracturing process is modelled.
References
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TL;DR: The distinct element method as mentioned in this paper is a numerical model capable of describing the mechanical behavior of assemblies of discs and spheres and is based on the use of an explicit numerical scheme in which the interaction of the particles is monitored contact by contact and the motion of the objects modelled particle by particle.
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Peter Cundall,Otto D. L. Strack +1 more
TL;DR: The distinct element method as mentioned in this paper is a numerical model capable of describing the mechanical behavior of assemblies of discs and spheres and is based on the use of an explicit numerical scheme in which the interaction of the particles is monitored contact by contact and the motion of the objects modelled particle by particle.
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TL;DR: This paper summarises the interpretation of the Hoek-Brown failure criterion which has been found to work best in dealing with practical engineering problems.