Abstract
Combination of the continuum-based numerical methods and the discrete element method (DEM) could be a powerful way of simulating complex problems. This approach benefits from the capabilities of both methods. The main feature of the discrete element method is that the soil grains are considered as individual particles without need to impose any behaviour law in modelling the medium. The limitation of this method is, however, its high computational demand. In continuum based methods, on the other hand, it is impossible to trace micro scale phenomena. According to these facts, combining continuum and discrete methods is an optimal way in approaching geotechnical problems which deal with granular soils. In this approach, the coarse grain zone (medium) is modelled using DEM and the surrounding media are modelled using the continuum methods. Stone columns that are widely used for improving and/or increasing the strength of weak soils could be modelled using this type of coupled simulation. The Coarse aggregates present in the stone column make it appropriate for the coupled modelling. In this paper, the ordinary and encased stone columns have been simulated by combining 2D DEM and finite difference method (FDM). Clump technique was employed to achieve the interlocking of aggregate particles in DEM, and the surrounding cohesive soil was modelled using FDM. The obtained results were validated by the reported experimental results in the literature, indicating that the coupled DEM-FDM method is a robust way to simulate stone columns.
Highlights
A robust way of simulating geotechnical problems is the combination of different numerical methods and utilizing the capabilities and benefits of each method
A new coupling method that has been employed in recent years by researchers for geotechnical modelling is the combination of continuum-based numerical methods -i.e., finite element method (FEM) and/or finite difference method (FDM) and discrete element method (DEM)
The constitutive models in the continuum methods are based on the experimental parameters, empirical assumptions and some simplifications that while predicting valuable information of the materials behaviour in macro scale, ignore some important granular materials characteristics in micro scale such as micro rotation, size, shape, interlocking of particles
Summary
A robust way of simulating geotechnical problems is the combination of different numerical methods and utilizing the capabilities and benefits of each method. A new coupling method that has been employed in recent years by researchers for geotechnical modelling is the combination of continuum-based numerical methods -i.e., finite element method (FEM) and/or finite difference method (FDM) and discrete element method (DEM). Materials in the discrete element method, on the contrary, are considered as individual particles without imposing any behaviour law. This novel discrete-nature numerical method was introduced in 1971 by Cundall [2] to analyse rock mechanics problems. DEM simulation deficiency, lies in the numerous particles needed for the realistic simulation of a medium. The results were validated using the experimental study which showed the robustness of this approach in modelling the complex systems
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