مهندسی عمران شریف (Aug 2020)
THREE-DIMENSIONAL MODELING OF ROCKFILL USING DEM CONSIDERING PARTICLE BREAKAGE
Abstract
Rockfill dams that are made by dumping and compacting rockfill materials are known as one of the most economical and safe dams. The main mechanical characteristics of rockfill depend on particle breakage. Particle breakage occurs when the stress levels are high enough or when the size of the particles is high enough as the rockfill particles. Particle breakage causes a change in grain size distribution of the media and causes a change in the mechanical properties of the granular media. Particle breakage is widely studied experimentally by classical laboratory tests, which need large and expensive equipment that is rarely available. Although numerical methods that are based on the continuum mechanics, such as finite element method, have been developed to be able to account for discontinuities; nevertheless, the internal discrete structure of the rockfill cannot be considered and physically modeled in this way. In addition, the fact is that these methods are not capable to simulate particle breakage to predict the mechanical properties of the rockfill materials. Discrete Element Method (DEM) can overcome these problems. In this research, discrete tri-dimensional modeling of rockfill behavior considering the particle breakage using DEM is studied. Particle breakage is modeled by a bonded particle model and, to consider particle breakage, a mechanical threshold criterion combined with a contact density of particles and a probabilistic criterion is used. PFC3D code and programming in FISH language were performed by investigating the resistance and deformation behavior. In addition, the effects of particle breakage during the tests were considered by providing a failure criterion. The model is compared with the experimental tests on Purulia rockfill dam materials, and the obtained results show good concordance with the obtained experimental results. Finally, the model and the presented failure criteria, whilst it has a simple computational procedure and high accuracy, were validated.
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