Evaluation of the Static and Pseudo-Static Stability and Effectiveness of an Improvement Technique for Slopes of the Vanyar Dam Reservoir

Abstract

Excavation on the inclined surfaces on the dam reservoir and rising water level may also affect the slope stability of the inclined surfaces in the dam reservoir under static and dynamic conditions. In this study, it is aimed to present a three-dimensional (3D) model to analyze slope stability of access road to the dam's crest and calculates the value of FOS in process of instructing and exploitation of dam and estimating the possibility of landslide occurrence during excavations and impounding of the dam. To this end, analysis of the slope stability has been implemented based on the information obtained from the field inspections, investigations, geological surveys, manual and mechanical borings in laboratory and field experiments. For acquiring the value of factor of safety (FOS), an explicit-finite-difference code is implemented. Effects of excavations in different levels of slope and fluctuation of water table in instability of the slope have been analyzed. The outcomes reveal that through increasing the level of water, FOS is decreased and large amounts of soil were entered in the dam's reservoir, blocking the entrance of the drainage valve and disrupt access way to the dam crest. Therefore, piles in the different distance have been used for controlling the slope stability and the best distribution of piles based on acceptable values for factor of safety in different regulations have been determined. It was observed that the excavation on the slope and increment of the water level in the dam reservoir influence the slope stability.