Abstract:
One of the most important factors that can be considered when it comes to assessing the
safety of an embankment dam is its slope stability. This study was conducted to analyse
the Chalchal embankment dam located in south east Ethiopia and aims to come up with
a list of helpful measures to prevent incidents. Geostudio-2018 software was employed
to analyse the seepage using SEEP/W, and SLOPE/W for slope stability analysis under
different cases of operations. Results of seepage analysis using SEEP/W was utilized as
a parental input for the analysis of SLOPE/W models. In this study, Seepage analysed to
determine seepage flow rate in dam body and foundation, pore water distribution and
location of phreatic line using the SEEP/W. Slope stability analysis was performed for
the critical slopes using the limit equilibrium method SLOPE/W software based on the
Morgenstern-Price method of safety factor. The stability evaluation results indicate that
the critical upstream and downstream slope of the proposed dam is not safe within the
prescribed USACE factors of safety for the possible loading and operation cases. This
necessitates proposed dam stability optimization to improve slope stability problem.
Based on the research findings removal off Alluvial deposit and replacing with material
with friction angel greater than 280
to solve slope stability problem of the dam, wise use
of construction material is very important because of huge volume of construction
material is needed in quality and quantity, clay quarry site around the project is varying
in depth and in quality as a result clay blending with each other is essential during
construction. Providing fine filter in between clay core and general foundation is essential
to protect clay particle movement to the foundation. Soluble rocks and sandstone rocks
when thinly bedded and well jointed as in the case of the study area, can lead to
thoughtful problems mainly in terms of shear strength and water-tightness. Therefore,
reservoir clay blanketing on the upstream river section is critical to reduce seepage to
the foundation. Seepage and load deformation analysis will be the future research area.
