Integrating Terrestrial Laser Scanning and Discrete Fracture Networks Approaches for Tunnel Modelling in Fractured Rock Masses

2016 ◽  
Author(s):  
Pedro Pazzoto Cacciari ◽  
Marcos Massao Futai
Keyword(s):  
Laser Scanning ◽  
Fractured Rock ◽  
Terrestrial Laser Scanning ◽  
Rock Masses ◽  
Fracture Networks ◽  
Discrete Fracture Networks ◽  
Discrete Fracture ◽  
Fractured Rock Masses

Numerically Simulated Groundwater Age Distributions within Complex Flow Systems and Discrete Fracture Networks

2020 ◽  
Author(s):  
John Molson ◽  
Emil Frind
Keyword(s):  
Groundwater Age ◽  
Fractured Rock ◽  
Vertical Plane ◽  
Geochemical Evolution ◽  
Real Field ◽  
Fracture Networks ◽  
Complex Flow ◽  
Discrete Fracture Networks ◽  
Discrete Fracture ◽  
Flow Systems

<p>Numerical simulations of mean groundwater age are presented for a variety of complex flow systems including heterogeneous aquifers and discretely-fractured porous rock. We apply the finite element models FLONET/TR2 (in the 2D vertical plane) and SALTFLOW (in 3D systems), using the standard advection-dispersion equation with an age source term. The age simulations are applied in a variety of contexts including defining capture zones for pumping wells, characterizing fractured rock aquifers, and for improved understanding of flow systems and geochemical evolution. Applications include real field sites and hypothetical conceptual models. Comparisons are also made with advective particle-tracking derived ages which are much faster to compute but do not include dispersive age mixing. Control of numerical (age) dispersion is critical, especially within discrete fracture networks where high age gradients can develop between the fractures and matrix. The presentation will highlight the broad applications of mean groundwater age simulations and will show how they can be useful for providing insight into hydrogeological systems.</p>

scholarly journals Correlations between Geometric Properties and Permeability of 2D Fracture Networks

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Xiaolin Wang ◽  
Liyuan Yu ◽  
Hanqing Yang
Keyword(s):  
Fractured Rock ◽  
Rock Fracture ◽  
Fractal Dimensions ◽  
Fracture Network ◽  
Network Structures ◽  
Rock Masses ◽  
Fracture Networks ◽  
Geometric Properties ◽  
Equivalent Permeability ◽  
Fractured Rock Masses

The equivalent permeability of fractured rock masses plays an important role in understanding the fluid flow and solute transport properties in underground engineering, yet the effective predictive models have not been proposed. This study established mathematical expressions to link permeability of 2D fracture networks to the geometric properties of fractured rock masses, including number density of fracture lines, total length of fractures per square meter, and fractal dimensions of fracture network structures and intersections. The results show that the equivalent permeability has power law relationships with the geometric properties of fracture networks. The fractal dimensions that can be easily obtained from an engineering site can be used to predict the permeability of a rock fracture network. When the fractal dimensions of fracture network structures and intersections exceed the critical values, the effect of randomness of fracture locations is negligible. The equivalent permeability of a fracture network increases with the increment of fracture density and/or fractal dimensions proportionally.

scholarly journals Equivalent continuum-based upscaling of flow in discrete fracture networks: The fracture-and-pipe model

2021 ◽  
Author(s):  
Maximilian O. Kottwitz ◽  
Anton A. Popov ◽  
Steffen Abe ◽  
Boris J. P. Kaus
Keyword(s):  
Fluid Flow ◽  
Numerical Simulations ◽  
Fractured Rock ◽  
Fracture Network ◽  
Fracture Networks ◽  
Computational Costs ◽  
Pipe Model ◽  
Discrete Fracture ◽  
Fractured Rock Masses ◽  
Equivalent Continuum

Abstract. Predicting effective permeabilities of fractured rock masses is a key component of reservoir modelling. This is often realized with the discrete fracture network (DFN) method, where single-phase incompressible fluid flow is modelled in discrete representations of individual fractures in a network. Depending on the overall number of fractures, this can result in significant computational costs. Equivalent continuum models (ECM) provide an alternative approach by subdividing the fracture network into a grid of continuous medium cells, over which hydraulic properties are averaged for fluid flow simulations. While this has the advantage of lower computational costs and the possibility to include matrix properties, choosing the right cell size for discretizing the fracture network into an ECM is crucial to provide accurate flow results and conserve anisotropic flow properties. Whereas several techniques exist to map a fracture network onto a grid of continuum cells, the complexity related to flow in fracture intersections is often ignored. Here, numerical simulations of Stokes-flow in simple fracture intersections are utilized to analyze their effect on permeability. It is demonstrated that intersection lineaments oriented parallel to the principal direction of flow increase permeability in a process termed intersection flow localization (IFL). We propose a new method to generate ECM's that includes this effect with a directional pipe flow parametrization: the fracture-and-pipe model. Our approach is tested by conducting resolution tests with a massively parallelized Darcy-flow solver, capable of representing the full permeability anisotropy for individual grid cells. The results suggest that as long as the cell size is smaller than the minimal fracture length and larger than the maximal hydraulic aperture of the considered fracture network, the resulting effective permeabilities and anisotropies are resolution-independent. Within that range, ECM's are applicable to upscale flow in fracture networks, which reduces computational expenses for numerical permeability predictions of fractured rock masses. Furthermore, incorporating the off-diagonal terms of the individual permeability tensors into numerical simulations results in an improved representation of anisotropy in ECM's that was previously reserved for the DFN method.

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