Abstract:
To attain the primary objective of seepage and slope stability analysis, the study has been
carried out based on primary and secondary data of Dora earth fill dam. The causes of
seepage problem have been identified using geophysical investigation report data of the
embankment and foundation, design document, site investigation and construction history of
the dam. Geo studio software is one of geotechnical program that is based on the finite
element and can consider analysis like stress-strain, seepage, slope stability, dynamic
analysis and also fast water drop in reservoir by assuming different mesh size. In this
research Geo studiosoftware has been used to calculate seepage and slope stability of
Dora earth fill dam. In this study seepage analysis has been done by seep/w software model
to evaluate the total f low rate through the dam cross section using three cases of seepage
analysis conditions. And case three or seepage analysis at normal pool level based on the
rearranged soil hydraulic conductivity material is selected for further analysis and to put some
mitigation measure and the result show that average flow rate of leakage under the case
using different mesh size including foundation seepage is equal to 0.079m
3
/s for the entire
length of the dam. This value is compared with the quantity of seepage estimated
practically at the down stream that is 0.072m
3
/s. Therefore, the practical measurement
almost has some uncertanity of quantifying the expected quantity of seepage. To this end,
problem of seepage at the downstream face of the dam which are threatening the dam
stability are expected to result from geology where the dams are located and the method
of investigation coupled with lack of experience in data collection and analysis and also
considering the construction history are the major factors attributed to this problem. And
Slope/W softw are is also used under different conditions to evaluate slope stability
calculation for each state and each slope with Bishop, Janbu, ordinary method of slides
and GLE methods is calculated and compared with the minimum acceptable safety factor
provided from United States army of Corps in each of these methods, beconsidered as a
safety factor of slope stability. To alleviate the seepage problem, upstream impervious
blanketing, downstream berming and Provision additional shoulder at the dawn stream
dam surface with clayey gravel soil construction are the proposed remedial measures.
