Fuzzy approach in preliminary design of weak rock slopes for lignite mines

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2013
Yardımcı, Ahmet Güneş
Slope mass rating (SMR) system, which is an enhanced version of rock mass rating (RMR), is a useful tool to be utilized for the preliminary stability analysis of rock slopes. Parameter scoring systems of both conventional RMR and SMR systems are based on crisp set theory. Common problems of conventional classification systems are assigning sharp boundaries for ranges, the same values for both upper and lower limits of ranges and presence of uncertainties as a result of complex nature of rock. These problems give rise to misleading final scores for rock or slope masses. In the scope of this study, the above mentioned problems of rock mass and slope mass classification systems will be aimed to be overcame by application of fuzzy set theory to RMR and SMR systems. For the preliminary stability assessment, slope performance chart suggested by Bieniawski was investigated in terms of its suitability to weak rock conditions. Later, the chart of Bieniawski was modified based on the back analysis data taken from real failure cases. Critical slope angles considering rock mass failure were determined from this chart using conventional and fuzzified RMR scores. After that, the SMR was used to investigate the structural failure mechanisms. Finally, SMR system was fuzzified similar to RMR by considering real failure cases. The result obtained from conventional and fuzzy systems were compared. It was observed that the fuzzified SMR and RMR produced more representative results than conventional RMR and SMR.

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Citation Formats
A. G. Yardımcı, “Fuzzy approach in preliminary design of weak rock slopes for lignite mines,” M.S. - Master of Science, Middle East Technical University, 2013.