Probabilistic and sensitivity analyses of effective geotechnical parameters on rock slope stability: a case study of an urban area in northeast Iran

Despite the development of cities, risk assessment of rock slope stability in urban areas seems not to be growing at the same time. Mashhad is a developed city in northeast of Iran with a population of over 2.4 million. Given the closeness of the southern part of Mashhad to the Binaloud mountain ridge, the stability of the residential complexes that are being constructed in this area is a critical issue. Based on the fundamental roles of discontinuity properties and geo-mechanical parameters of rock mass, in this study we evaluated the most influential parameters of the rock slope stability and the failure probability of the slope near the Negin residential complex built on this ridge. According to the deterministic and probabilistic analyses, the north trench that was excavated for this residential complex could potentially cause plane failure. Moreover, the relationship between effective parameters on instability and their impact on safety factors were determined by sensitivity analysis. Therefore, slope dip, pore water pressure, and joint set dip were highly influential on the safety factor. There was also a nonlinear relationship between different parameters and safety in the studied area. This study presents an approach for risk assessment of rock slope stability in urban areas.