Numerical simulation of breakages of concrete armour units using a three-dimensional fracture model in the context of the combined finite-discrete element method

Guo, Liu; Latham, John; Xiang, Jiansheng

doi:10.1016/j.compstruc.2014.09.001

Cited by 50 publications

(31 citation statements)

References 30 publications

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“…cohesive zone) method that can capture the non-linear stress-strain behaviour of the plastic zone ahead of a fracture tip (Munjiza et al 1999). Such a crack propagation model has been recently implemented into the 3D FEMDEM formulation Guo et al 2015Guo et al , 2016. The equations of motion of the FEMDEM model are solved through an explicit time integration scheme based on the forward Euler method.…”

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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“…The solid dynamics is resolved by the combined finite-discrete element method (FEMDEM) [46,49], which combines deformable fracturing arbitrary-shaped particle interactions modelled by the Finite Element Method (FEM) with discrete particulate motions modelled by the Discrete Element Method (DEM). The research code Y2D is coupled with the fluid model (Fluidity).…”

Section: Governing Equations For Solid Dynamicsmentioning

confidence: 99%

“…For additional details, see [46,49]. In FEMDEM, FEM is used to model the solid behaviour as described by continuum mechanics and switches to DEM when a fracture is generated.…”

Section: Governing Equations For Solid Dynamicsmentioning

confidence: 99%

“…The overall fracture modelling algorithm, based on FEMDEM, is given in Algorithm 1 (for details, see [49,52]), where u t solid denotes the solid velocity vector at each node at time t, u acceleration is the acceleration, f external and f internal are the external and internal forces at each node respectively, and mass denotes the nodal mass.…”

Section: Fracture Modellingmentioning

confidence: 99%

“…A 4-noded joint element is then inserted between two triangular elements, and the stresses are calculated using FEM. The new fractures are judged by the Mohr-Coulomb criterion with a tension cut-off, see normal stress is less than the tensile strength, the shear stress in a joint element can be expressed by Equation (12) [49].…”

Section: Fracture Modellingmentioning

confidence: 99%

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A non-intrusive reduced-order model for compressible fluid and fractured solid coupling and its application to blasting

Xiao¹,

Yang²,

Fang

et al. 2017

Journal of Computational Physics

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This work presents the first application of a non-intrusive reduced order method to model solid interacting with compressible fluid flows to simulate crack initiation and propagation. In the high fidelity model, the coupling process is achieved by introducing a source term into the momentum equation, which represents the effects of forces of the solid on the fluid. A combined single and smeared crack model with the MohrCoulomb failure criterion is used to simulate crack initiation and propagation. The non-intrusive reduced order method is then applied to compressible fluid and fractured solid coupled modelling where the computational cost involved in the full high fidelity simulation is high. The non-intrusive reduced order model (NIROM) developed here is constructed through proper orthogonal decomposition (POD) and a radial basis function (RBF) multi-dimensional interpolation method.The performance of the NIROM for solid interacting with compressible fluid flows, in the presence of fracture models, is illustrated by two complex test cases: an immersed wall in a fluid and a blasting test case. The numerical simulation results show that the NIROM is capable of capturing the details of compressible fluids and fractured solids while the CPU time is reduced by several orders of magnitude. In addition, the issue of whether or not to subtract the mean from the snapshots before applying POD is discussed in this paper. It is shown that solutions of the NIROM, without mean subtracted before constructing the POD basis, captured more details than the NIROM with mean subtracted from snapshots.

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A new approach to upscaling fracture network models while preserving geostatistical and geomechanical characteristics

et al. 2015

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A new approach to upscaling two-dimensional fracture network models is proposed for preserving geostatistical and geomechanical characteristics of a smaller-scale "source" fracture pattern. First, the scaling properties of an outcrop system are examined in terms of spatial organization, lengths, connectivity, and normal/shear displacements using fractal geometry and power law relations. The fracture pattern is observed to be nonfractal with the fractal dimension D ≈ 2, while its length distribution tends to follow a power law with the exponent 2 < a < 3. To introduce a realistic distribution of fracture aperture and shear displacement, a geomechanical model using the combined finite-discrete element method captures the response of a fractured rock sample with a domain size L = 2 m under in situ stresses. Next, a novel scheme accommodating discrete-time random walks in recursive self-referencing lattices is developed to nucleate and propagate fractures together with their stress-and scale-dependent attributes into larger domains of up to 54 m × 54 m. The advantages of this approach include preserving the nonplanarity of natural cracks, capturing the existence of long fractures, retaining the realism of variable apertures, and respecting the stress dependency of displacement-length correlations. Hydraulic behavior of multiscale growth realizations is modeled by single-phase flow simulation, where distinct permeability scaling trends are observed for different geomechanical scenarios. A transition zone is identified where flow structure shifts from extremely channeled to distributed as the network scale increases. The results of this paper have implications for upscaling network characteristics for reservoir simulation.

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Numerical simulation of breakages of concrete armour units using a three-dimensional fracture model in the context of the combined finite-discrete element method

Cited by 50 publications

References 30 publications

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

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

A non-intrusive reduced-order model for compressible fluid and fractured solid coupling and its application to blasting

A new approach to upscaling fracture network models while preserving geostatistical and geomechanical characteristics

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