This paper presents data from ring-shear and one-dimensional compression tests, which have been used to cause breakage under large shear strains and large compressive stresses respectively. A comparison of the behaviour of carbonate sand in monotonic shear and compression is reported, focusing on void collapse, grading properties and particle shape evolution. Trends in breakage behaviour under compression and under shear were similar; however, ultimate steady-state properties differed significantly. The higher effect of shear breakage was evident, in that the steady-state gradings for sheared material had higher fractal dimensions, indicating that the gradings were finer, and morphological changes in particle shape were more significant. Steady-state gradings tended to be multi-fractal in nature rather than mono-fractal, and showed that a unique monotonic steady-state grading does not exist. Two types of ring-shear device were compared, and the differences between the results highlighted a dependence of steady-state properties on test apparatus configuration.
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OVERVIEW OF WORKSHOPThe importance of integrating tasks that are relevant to graduate practice into the engineering curriculum has been widely recognised. One key approach is project-based learning; however, there are significant barriers to improvement and wider adoption of practice-based approaches-including (but not limited to) the cost of scaling up projects for large cohorts, appropriately qualified teaching staff, organisational structures-which can lead to inauthentic approaches and staff attrition.The team has received an AAEE engineering education grant to identify current best practice and support mechanisms for project-based learning. The project will provide greater clarity to teaching staff on what best practice in project-based learning is and what support they ought to seek from their T&L leadership for their project-based learning courses. The purpose of the workshop is to share and discuss preliminary data from the team's project and provide an opportunity to share experiences of running project-based learning.
ACTIVITIESGroup-facilitated discussion around experiences of teaching via project-based learning will be conducted. Exemplars of project-based learning practice and support mechanisms for successful project-based learning will be provided by workshop facilitators and followed by semi-structured group facilitated discussions.
Landslides due to catastrophic weather events, especially heavy rainfall, have risen significantly over the last several decades, causing significant damage and affecting the health and livelihoods of millions of people. Using tree roots to bio-engineer shallow slopes has been proven to be a cost-effective, sustainable measure and thus has gained increasing popularity. As slope failure often occurs under heavy precipitation, it is important to understand the mechanical interactions in the soil matrix surrounding a root to better estimate the reinforcement capacity of a root system, especially as the soil undergoes wetting from drier conditions. However, very few studies of root reinforcements have considered the effects of degree of saturation on behaviour. In this study, steel wires are used as a root analogue to explore the impact of root geometry, soil dilation and soil saturation on the pull-out behaviour of a root and three commonly used unsaturated soil strength models have been used to interpret the pull-out results. It was found that roots with larger diameter did not contribute to additional resistance. Also, a linear relationship between degree of saturation and pull-out strength was identified over a large range of suctions and one of the unsaturated soil strength models seemed to provide a more reasonable interpretation. The results will help future bioengineering slope design by improving the understanding of soil-root interface behaviour, including the effect of root diameter in slippage failure and greater emphasis on the importance of taking degree of saturation into account in unsaturated soil strength models.
Abstract. Experimental breakage studies have often focused on comparing grading and particle shape data from the beginning and end of a test, but one major advantage of DEM simulations is that, although the data are still discrete, more information on intermediate stages is available. This paper describes a repetitive compression test using a 2D aggregate-based DEM model comprised of spheropolygonal particles (formed by the Minkowski sum of a circle and a polygon, viz. sweeping a circle around the edges of the polygon) that are connected by beams and compares the behaviour with experimental data on the breakage of Barrys Beach carbonate sand. The one-dimensional repetitive compression test was performed on 20 particles-each consisting of over 100 sub-particles-which were generated from the outlines of particles of Barrys Beach carbonate sand. Particle breakage was described through the breakage of beams (particle bonds), allowing the evaluation of changes in the compressibility and grading. It was noted that the simulation compared well with the experimental behaviour of Barrys Beach carbonate sand.
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