Browsing by Author "Surujbally, Shivana"
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- ItemThe identification and modelling of rockfalls for protection measures in the Western Cape(Stellenbosch : Stellenbosch University, 2016-03) Surujbally, Shivana; De Wet, Marius; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: Natural slopes and man-made cuttings in weathered, highly jointed or fractured rock with unfavourable bedding planes can result in the release of rock blocks either from above these slopes and cuttings or from the face itself resulting in what is termed a “Rockfall”. Rockfalls are a global phenomenon and much research has been done in countries like Switzerland, Italy, United States of America and Canada. Some of these countries have contributed to the field by developing their own software packages to model potential rockfalls or those rockfalls that have already occurred and assist in locating the position of rockfall mitigation measures such as catch fences. This research project covers the occurrence of rockfalls at three specific sites within the Western Cape in South Africa. This project was undertaken as very little is known about rockfalls in the Western Cape, let alone South Africa. And what little is known is not well documented or published. Three sites were chosen which included Chapman’s Peak Drive, Sir Lowry’s Pass and The Cliffs. Chapman’s Peak Drive is a world renowned pass located on the Western side of the peninsula, whilst Sir Lowry’s Pass is located between Somerset West and Grabouw and forms part of the National Route 2. The Cliffs used to serve as a hard rock quarry and is located in Tygervalley and now forms the backdrop to office complexes. The geology of two of the three sites that were studied is located in the Malmesbury Group, which covers a large percentage of the Western Cape, whereas the third site is located in both the Table Mountain Supergroup and the Cape Granite. The aim of the research project was to combine the collection of data through fieldwork with rockfall software programs in areas that are known to have experienced rockfalls to assist in mitigating the problem by avoiding over design and thereby reducing the overall cost of the project. This was achieved by the use of ArcGIS 10.0, Rapid Mass Movement System (RAMMS) Rockfall (trial version) and Rocscience Rocfall 4.0. Field inspections were carried out for each of the study areas, followed by terrestrial surveys. The terrestrial survey information was used to produce an ASCII file which is the required input file for RAMMS and produces 3D trajectory paths when a rockfall simulation is run. The trajectories were exported from RAMMS and draped over a 3D rendered a view of each site Stellenbosch University https://scholar.sun.ac.za iv for better viewing of the paths. These trajectories were then traced in AutoCAD and imported into the 2D Rocscience Rocfall software. The rockfall simulation was carried out in Rocfall and are presented in this research project. The outcome of this project concluded that rockfall software programs are undoubtedly useful in engineering design to mitigate rockfalls and reduce overall costs of a project. However, like with anything else man-made, software programs are not without flaws and cannot replace an experienced person in the field. Unrealistic software results can only be distinguished by someone who understands the behaviour of rockfalls as certain parameters such as the coefficients of restitution require educated assumptions since there is no South African field tested database currently. Although creating a local database of these parameters will be a costly undertaking, it would significantly improve the confidence for results produced by the rockfall software programs and therefore, this warrants further research into this field.