Page 66 - Teaching Innovation for the 21st Century

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Teaching Innovation for the 21st Century | Showcasing UJ Teaching and Learning 2021
For engineering geology, the first practical assessment involves and trains students on distinguishing soil from rock based on several key descriptors used in industry, based on the MCCSSO soil classification scheme. A soil profile, with the descriptions for the various layers (horizons) indicated, is provided to the students (Figure 3); on the basis of the descriptions, the students are asked questions relating to various properties of the different soil horizons that may be present within the specific profile. In addition to the properties of individual horizons, students are also able differentiate between residual and transported soils. The former are soils formed from the rock on which they are sitting, whereas the latter are soils that have moved (eroded) from one place to their current location.
Figure 3: An example of a soil profile including descriptions of the horizons using the MCCSSO classification scheme
Three subsequent practical assessments build on the first with students working with sieve analysis data from real-world examples (Figure 4A). The students then plot the data on soil grading curves (Figure 4B); this allows the students to visualise the data and to determine the amounts of different soil components (gravel, sand, silt and clay) based on the shape of the resulting curve (Figure 4B). Based on the proportions of the components, the students can determine properties such as the uniformity coefficient which is indicative of soil composition and potential engineering geological problems that may be associated with the soil. For example, a soil dominated by sand is likely collapsible when wet, whereas one dominated by clay may develop a shrink-swell character depending on moisture content and the type of clay. The proportion of the components in the soil also gives an indication of the drainage (water-holding capacity) properties of the soil; a soil dominated by one component would be described as ‘well-drained’ and a soil comprising of different components would be less porous and be described as ‘poorly drained’. With each practical, the students’ knowledge is progressively developed and built.