The effect of cohesion and level of groundwater on the slope instability using finite element method [ ]

Slope stability analysis is one of the most important topics in geotechnical engineering. Slope stability can be analyzed using one or more methods. Analytical and numerical methods are available but numerical methods are quickly, reliable, accurately and so we able to perform parametric and comprehensive study of slope stability with complex boundary conditions. In this research numerical analysis by finite element software PLAXIS version 8.5 showed that the slope angle and rainfall has the most influence in the safety factor analysis. Also for layered slope variable cohesion or friction angle for each layer has been investigated. The analysis has been done using Mohr-Coulomb constitutive model. The slope stability analyses are performed to assess the safe and economic design of human-made or natural slopes (e.g. embankments, road cuts, open-pit mining, excavations, and landfills). In the assessment of slopes, engineers primarily use factor of safety values to determine how close or far slopes are from failure. When this ratio is greater than 1, resistive shear strength is greater than driving shear stress and the slope is considered stable. When this ratio is close to 1, shear strength is nearly equal to shear stress and the slope is close to failure, if FS is less than 1 the slope should have already failed. Thus, for this research the critical safety factor is considered 1. This means that in parametric study, change in the value of soil cohesion continues until the FS is equal to 1.