Scientific African (Jul 2021)
Assessment of rock slope stability using slope stability probability classification (SSPC) system, around AlemKetema, North Shoa, Ethiopia
Abstract
This research was conducted in an area around AlemKetema, North Showa, central Ethiopia; with a general objective of conducting a rock slope stability assessment on the selected natural rock slope sections. To achieve this objective, slope stability probability classification was followed to determine the stability probability conditions of slope rock mass in the study area. These classification systems mainly depend on the primary data collected from field works. As a reason, systematic and extensive fieldwork was conducted. However, secondary data was also required to characterize the general conditions of the study area and to have a deep understanding of the subject matter. In the SSPC system, ratings for the degree of weathering, intact rock strength, method of excavation, roughness condition, and infill material were given according to standards. The slope stability probability classification (SSPC) system practices three-step classification systems. These steps are exposure rock mass, reference rock mass, and slope rock mass. Following these steps, slope rock mass stability probability classifications have been carried out for 92 natural rock slope sections. The stability of slope rock mass was determined by two different approaches namely orientation-dependent and orientation independent stability. Orientation dependent stability is linked with the orientation of the discontinuities and characterized by toppling and sliding criteria, while orientation independent stability is linked with the strength of slope rock mass. Accordingly, the overall assessment indicated that 80.4% of rock slope sections showed less than 5% stability probability, 10.9% of rock slope sections showed from 5 to 49%, 6.5% showed from 50 to 95%, and the rest 2.2% of rock slope sections showed greater than 95% stability probability. All these results were compared with the visual stability assessment results. Accordingly, different stability probability maps were produced.
