Y-Geo: New Combined Finite-Discrete Element Numerical Code for Geomechanical Applications

Mahabadi, O. K.; Lisjak, A.; Munjiza, Ante; Grasselli, Giovanni

doi:10.1061/(asce)gm.1943-5622.0000216

Cited by 305 publications

(117 citation statements)

References 28 publications

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“…Extensive developments and applications of the FEMDEM method have been conducted in the past decade or so with different versions having emerged such as the code collaboratively developed by Queen Mary University of London (UK) and Los Alamos National Laboratory in the USA (Munjiza et al 2011(Munjiza et al , 2013Rougier et al 2014), the YGeo and Irazu by the University of Toronto, Canada (Mahabadi et al 2012;Lisjak and Grasselli 2014;Lisjak et al 2017), and the Solidity platform by Imperial College London (Xiang et al 2009a, b;Guo et al 2016;Lei 2016;Lei et al 2016). The FEMDEM model that accommodates the finite strain elasticity coupled with a smeared crack model is able to capture the complex behaviour of fractured rocks involving deformation, displacement, rotation, interaction, fracturing and fragmentation.…”

Section: Finite-discrete Element Methods (Femdem)mentioning

confidence: 99%

Polyaxial stress-dependent permeability of a three-dimensional fractured rock layer

et al. 2017

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A study about the influence of polyaxial (true-triaxial) stresses on the permeability of a three-dimensional (3D) fractured rock layer is presented. The 3D fracture system is constructed by extruding a two-dimensional (2D) outcrop pattern of a limestone bed that exhibits a ladder structure consisting of a Bthrough-going^joint set abutted by later-stage short fractures. Geomechanical behaviour of the 3D fractured rock in response to in-situ stresses is modelled by the finite-discrete element method, which can capture the deformation of matrix blocks, variation of stress fields, reactivation of pre-existing rough fractures and propagation of new cracks. A series of numerical simulations is designed to load the fractured rock using various polyaxial in-situ stresses and the stress-dependent flow properties are further calculated. The fractured layer tends to exhibit stronger flow localisation and higher equivalent permeability as the far-field stress ratio is increased and the stress field is rotated such that fractures are preferentially oriented for shearing. The shear dilation of pre-existing fractures has dominant effects on flow localisation in the system, while the propagation of new fractures has minor impacts. The role of the overburden stress suggests that the conventional 2D analysis that neglects the effect of the out-of-plane stress (perpendicular to the bedding interface) may provide indicative approximations but not fully capture the polyaxial stress-dependent fracture network behaviour. The results of this study have important implications for understanding the heterogeneous flow of geological fluids (e.g. groundwater, petroleum) in subsurface and upscaling permeability for largescale assessments.

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Section: Finite-discrete Element Methods (Femdem)mentioning

confidence: 99%

Polyaxial stress-dependent permeability of a three-dimensional fractured rock layer

et al. 2017

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“…Munjiza [27] developed a combined finite-discrete element method (FDEM), in which elasticity calculations are based on continuum finite element methods, and discontinuous behavior is represented by a discrete method. Whereas the transition from continuous to discontinuous behavior needs proper attention [5], [29], [30], [34], FDEM capably simulates both elasticity and failure processes of geomaterials, as demonstrated through comparisons with theory and laboratory studies [26], [24]. Munjiza et al [28] cover several methods that describe physical systems using discrete entities.…”

Section: Introductionmentioning

confidence: 99%

Simulating the Poisson effect in lattice models of elastic continua

Asahina

Ito

Houseworth

et al. 2015

Computers and Geotechnics

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Lattice models provide discontinuous approximations of the displacement field over the computational domain, which facilitates the modeling of fracture and other discontinuous phenomena. By discretizing the domain with two-node elements, however, ordinary lattice models cannot simulate the Poisson effect in a local (intra-element) sense, which is problematic for some types of analyses.Furthermore, such methods are limited in the range of Poisson ratio values that can be simulated. We present a new approach to remedy such known, yet underappreciated, shortcomings of lattice models. In this approach, the Poisson effect is modeled through the introduction of fictitious stresses into a regular lattice. Capabilities of the new approach are demonstrated through compressive test simulations of homogeneous and heterogeneous materials. The simulation results are compared with theory and those of continuum finite element models. The comparisons show good agreement for arbitrary Poisson ratios (including ν ⩾ 1/3) with respect to nodal displacement, intra-element stress, and nodal stress. This form of discrete method, supplemented by the proposed fictitious measures of stress, retains the simplicity of collections of two-node elements.

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“…In particular, these models can properly represent the behavior of historical masonry constructions, which could be considered as made of dry stone blocks exhibiting a periodic pattern. The combination of DEM and FEM provided by the open source code Y2D, developed by prof. A. Munjiza [2] and implemented by Geo Group of Toronto University [3,4] allows to further extend the study to both linear and nonlinear masonry behavior. In particular blocks can be assumed to behave (differently from DEM described above) as elastic bodies while mortar joints might be idealized as elastic or elastic-plastic zero-thickness Mohr-Coulomb interfaces.…”

Section: Fem/dem Modelmentioning

confidence: 99%

“…Blocks are modeled by means of finite elements while interfaces are modeled as discrete elements. The FEM/DEM analysis is carried out by using an open source code, Y2D, developed by prof. A. Munjiza [2] and implemented by Toronto Group [3,4], who is one of the pioneers of this coupling technique.…”

Section: Introductionmentioning

confidence: 99%