Slope stability analysis considering fully saturated poro-elasto-plasticity by an image-based scaled boundary finite element approach
- Authors: Wijesinghe, Dakshith , Dyson, Ashley , You, Greg , Khandelwal, Manoj , Natarajan, Sundararajan , Chan, Andrew , Ooi, Ean Tat
- Date: 2024
- Type: Text , Journal article
- Relation: Engineering Analysis with Boundary Elements Vol. 158, no. (2024), p. 160-181
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- Description: Open pit mines are large geotechnical structures. Their stability is an important consideration in the mining industry. The deformations of geotechnical structures often involve the coupled interaction between the pore fluid pressure and the nonlinear deformation of soil, characterised by poro-elasto-plastic behaviour. This paper develops the scaled boundary finite element method (SBFEM) to address poro-elasto-plastic in slope stability problems. It builds upon a previously developed elasto-plastic formulation to consider the effect of pore fluid pressure and its interaction with the nonlinear deformation within the soil. The pore pressure field introduces an additional variable in the governing equations that is similarly discretised using SBFEM shape functions. The SBFEM is implemented together with a pixel-based quadtree mesh generation technique, enabling automatic meshing directly from digital images. This leads to efficient automation when modelling problems with iterative changes in the geometry such as in optimisation of construction processes during the rehabilitation of slopes. The formulation is validated first using a standard numerical benchmark. Application of the developed technique in construction applications in slopes where the stability and effect of pore water pressure is considered e.g., tailings dam construction and optimisation of backfilling process is demonstrated in three examples to demonstrate feasibility. © 2023 The Authors
A 2-D polygon discrete element method and program for simulating rockfill materials
- Authors: Luo, Tao , Ooi, Ean Tat , Chan, Andrew , Fu, Shaojun
- Date: 2017
- Type: Text , Journal article
- Relation: Yantu Lixue/Rock and Soil Mechanics Vol. 38, no. 3 (2017), p. 883-892
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- Description: Every single particle is simulated by a polygon discrete element to capture the realistic shape of rockfill materials. A polygon discrete element method (PDEM) is developed by adopting a simple contact detection program and a polygon/polygon contact model. A linear program is adopted to detect the contact details between polygons. Then the normal contact force is calculated by a potential energy based polygon/polygon normal contact model, and a polygon discrete element calculation method is formed. Based on this method, a program called PDEM is developed to study the interaction between particles and both the translational and rotational motion of every particle from the microscopic view. The effect of micro-properties (e.g. particle shape, size, material properties et al.) on the macro-strength and deformation is enabled. A two-dimensional model test of a coarse aggregate was carried out by PDEM program. The stress and deformation laws consistent with the lab experiment were obtained, and the method and procedure were used to study the effectiveness of the rockfill. © 2017, Science Press. All right reserved.
A combined DEM-SBFEM for modelling particle breakage of rock-fill materials
- Authors: Luo, Tao , Ooi, Ean Tat , Chan, Andrew , Fu, Shaojun
- Date: 2017
- Type: Journal article
- Relation: Yantu Lixue/Rock and Soil Mechanics Vol. 38, no. 5 (2017), p. 1463-1471
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- Description: Both experimental and numerical results demonstrate that particle breakage has significant influence on the macro mechanical response of granular soils. In this study, a novel computational method was proposed to simulate particle breakage phenomenon in granular soils. The proposed method based on the discrete element method (DEM) and the scaled boundary finite element method (SBFEM) has advantages of each method. Individual grains of soil are modelled by a single star-convex polygon with an arbitrary number of sides. The DEM is used to determine the motion of particles and the interaction among particles, whereas the SBFEM is applied to obtain stress states of grains at the end of each time step. Since the SBFEM flexibly describes the morphology of each grain with a single polygon consisting of an arbitrary number of sides, it greatly reduces the necessary computational resources for stress analysis. When the stress state has been confirmed, Hoek-Brown criterion is chosen to determine the 'plastic points' within each particle. Once the ratio of 'plastic points' reaches a predefined threshold, the particle breakage is triggered. As a straight breakage line is assumed for simplification, the particle is split into two when breakage occurs. The newly generated polygons are directly modelled by the DEM and SBFEM without any change of the formulation, and thus this method does not need to predefine sub-particles and re-meshing elements. At last, the feasibility of the newly developed method is verified by a biaxial benchmark test. © 2017, Science Press. All right reserved.
The combined scaled boundary finite-discrete element method : Grain breakage modelling in cohesion-less granular media
- Authors: Luo, Tao , Ooi, Ean Tat , Chan, Andrew , Fu, Shaojun
- Date: 2017
- Type: Text , Journal article
- Relation: Computers and Geotechnics Vol. 88, no. (2017), p. 199-221
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- Description: A computational technique combining the scaled boundary finite element method (SBFEM) and the discrete element method (DEM) is developed. Both methodologies work in tandem to model two mechanisms i.e. grain-to-grain interaction via DEM; and breakage of individual grains via SBFEM. Both play important roles in characterising the response of granular soils. The combination of the two methods results in some advantages in computational flexibility and implementation in modelling grain breakage in granular materials. Parametric studies demonstrate the method's ability to reproduce stress-strain curves in bi-axial tests of granular rock-fills; and qualitatively predicts characteristics of grain breakage observed in laboratory tests. © 2017 Elsevier Ltd