Use of particulate mechanics concept in agricultural and geotechnical engineering applications
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Date
2019-11-11
Authors
Adajar, Joash Bryan
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Abstract
Discrete Element Method (DEM) is a numerical process that uses the concept of particulate mechanics, and it is capable of modelling the discontinuous response of particulate materials. It was utilized in this research for agricultural and geotechnical engineering applications.
In an agricultural engineering application, the particle contact microparameters of various crop residues - canola, corn, flax, oats, and wheat - and their interfaces with soil were characterized. These microparameters can be used to improve the reliability of soil-tool-residue DEM models, which in turn is important for the design of high-performance soil-engaging tools. Microparameters for the materials were determined by using a calibration methodology. Laboratory tests were initially performed to obtain information on the macroscopic behavior of the material. Then, discrete element models of the tests were generated to back-calculate the microparameters by simulating the laboratory test results. Linear contact model, with particle stiffness and friction as microparameters, was used to describe the behavior of the interactions between crop residue particles and of the soil-residue interfaces. Ring shear test was conducted to identify the internal friction angle of the crop residues, while direct shear test was carried out to measure the friction angle of the soil-residue interfaces. The DEM models of ring shear and direct shear tests were then developed and used in simulating the measured test results. The DEM simulations of both tests were found to efficiently calibrate the microparameters for residue-residue and soil-residue interactions.
In a geotechnical engineering application, the microparameters of the main constituents of an earth fill dam were characterized by conducting DEM simulations of triaxial and large-scale direct shear tests. These microparameters were utilized in developing a landslide DEM model that simulated the observed excessive movements (landslide) in the dam. Validation of the DEM model was successful as it was able to simulate the observed depression at the crest and bulging at the toe of the dam. The DEM model can then be used as basis in assessing the risks of future slope movements in other similar earth fill dam.
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Keywords
DEM, Particulate, Landslide, Tillage, Calibration