| Abstrak/Abstract |
Abstract: The Pidekso Dam is one of the National Strategic Projects. The dam is located in Pidekso Village, Giriwoyo District,
Wonogiri Regency, Central Java Province. The dam was designed as an earth-fill dam of zonal type with random fill and an
upright core. Although the construction of a dam provides huge benefits, it may pose a potential hazard if collapses. Therefore,
it is necessary to conduct a study to determine the safety of the Pidekso Dam in various conditions, including during an
earthquake occurrence. The study analyzed the seepage on the main dam construction using Seep/W and dam-slope stability
using Slope/W by reviewing the cross-section of the dam body and its foundation. The data used as the input in the analysis
include the coefficient of soil permeability, soil cohesion, internal friction angle, and soil density based on field investigations
and laboratory analysis. For the seepage analysis, manual calculations were also carried out using the Schaffernak and
Casagrande method compared to the Seep/W results. From the results of the seepage analysis with Seep/W, the Pidekso Dam is
safe against leakage with the largest discharge of 6.480×10
-4
m
3
/s at maximum water level. The safety factor against piping
showed safe results with the lowest safety factor of 6.295 at the end of the filter drainage. In the dam stability analysis with
Slope/W, several unsafe conditions have the lowest safety factor of 0.926 on the upstream slope at the minimum water level with
MDE (Maximum Design Earthquake) of 0.25. In Makdisi-Seed analysis, the highest slope displacement value is 0.862 m with
an earthquake magnitude of 8.25; Y/H (Y is the depth from the top of the dam and H is dam height) of 0.25. This value is smaller
than the maximum limit of 2.00 m, hence the dam is still in a safe condition. |
