The Evaluation of Failure Structure Condition with Plaxis Program on the Poso I Hydropower Barrage

The Poso I Hydropower Station is located on the Poso River, at the downstream section of the Poso Lake in Central Sulawesi Province. At the weir site, the catchment area is 1906.30 km2, and the structures are designed for a 50 year return period. Flood discharge is 1456.50 m3/s, with the mean annual release being 127.85 m3/s. The total supply water level is 510.50m, and the minimum operating level is 506.00 m. The model uses an undistorted model with a scale of 1 to 60. The barrage needs to be reviewed for failure factors that are likely to occur similar to those used in potential failures in the construction of dams in general. The study was considered in three conditions: empty barrage condition, average level, and flood level. With the piping calculation method, the barrage used Lane and Bligh method. While the calculation of barrage sliding stability used Finite Element Method with Plaxis 2D program simulation got the safety factor at the empty condition and flood level. It is caused by water pressure at flood level conditions that influence barrage stability. Safety factor value exceeded permits made. The Poso I Hydropower Station was safe.

Probabilistic Seismic Analysis of the Deep Sliding Stability of a Concrete Gravity Dam-Foundation System

There are various uncertainties in the design, construction, and operation of dams. These uncertainties have an important impact on the seismic response and seismic safety evaluation of concrete dams. In this research, a typical nonoverflow monolith of a concrete gravity dam is selected as a case study for the sliding stability analysis. Based on the analysis and demonstration of parameter sensitivity of friction coefficients and cohesion and their influence on the deep antisliding stability of the dam-foundation system, the probabilistic seismic analysis of a gravity dam-foundation system is carried out through Monte Carlo analysis with a large sample number. Damage levels are defined based on the sliding instability failure mode along with the corresponding threshold values of the damage index. Thus, seismic fragility analysis is investigated, and seismic fragility curves are obtained for the vulnerability assessment under earthquake hazards. The overall seismic stability of the gravity dam is evaluated, which provides the basis for the seismic safety evaluation in the probabilistic framework.

Translational and Sliding Stability for Two-Dimensional Minimal Cones in Euclidean Spaces

In this article, we prove the translational stability for all two-dimensional Almgren minimal cones in ${\mathbb{R}}^n$ and the Almgren (resp. topological) sliding stability for the two-dimensional Almgren (resp. topological) minimal cones in ${\mathbb{R}}^3$. As proved in [ 19], when several two-dimensional Almgren (resp. topological) minimal cones are translational, Almgren (resp. topological) sliding stable, and Almgren (resp. topological) unique, their almost orthogonal union stays minimal. As a consequence, the results of this article, together with the uniqueness properties proved in [ 14], permit us to use all two-dimensional minimal cones in ${\mathbb{R}}^3$ to generate new families of minimal cones by taking their almost orthogonal unions.

Kajian Stabilitas Lereng dengan Perkuatan Geotekstil dan Dinding Penahan Tanah Kantilever di Ruas Jalan Padang-Lb. Selasih Sumatera Barat

A typical relatively steep slope makes the Lb. Selasih – Bts. Kota Padang KM.29+650 experienced a landslide in 2017. So, it is necessary to strengthen the slope to overcome the landslide. Alternative slope reinforcement used is reinforcement using cantilever retaining walls or geotextiles. Slope stability analysis before and after were analyzed using the Slope/W program. The output produced by Slope/W program is the value of the safety factor. The safety factor value for the state of the original slope is 1.100. It shows that the slope in the original condition is unstable and vulnerable to landslide hazards. The retaining wall has a height of 11 m and a base plate width of 8 m. The results of the analysis showed that the cantilever retaining wall securely with stands shear, rolling, and bearing capacity of the subgrade with a safety factor value of 1.620; 1.550; 2.160, while geotextile reinforcement has a height of 16 m and an ultimate tensile strength of 200 kN / m. The results of the analysis showed that the reinforcement of the geotextile safely sliding, stability, and bearing capacity of the subgrade with a safety factor value of 1.600; 2.330; 2.860. Both of these reinforcements are safe to stabilize the slope by increasing the value of the slope safety factor by 2.235 for strengthening the cantilevered retaining wall and 2.279 for strengthening the geotextile.

Sliding failure analysis of a gabion retaining wall at km 31+800 of Lubuk Selasih – Padang city border highway, Indonesia

In August 2010, there was a landslide on the down-slope of national road section at Km 31+800 Lubuk Selasih – Padang City Border. In order to prevent further damage, it was necessary to make an immediate repair by constructing a gabion retaining wall. Since this repair was so urgent, physical and mechanical soil parameters for the stability analysis were determined from literature data. The stability analysis considered dangers of overturning, sliding, and soil bearing capacity. For the sliding stability analysis, the value for friction considered only the interaction between the soil and the base of the retaining wall, with the assumption that the contact area was equal to the total area of the entire base of the retaining wall. After the construction was completed, sliding failure occured due to pressure from the backfill embankment. This research performs a reanalysis of the retaining wall stability using soil and gabion parameters determined from field investigation and laboratory testing. In this reanalysis the friction contact area was assumed to be between the soil and the wire mesh of retaining wall. With these parameters and assumption, the main cause of sliding failure became clear, indicating that this approach increased the accuracy of stability analysis for gabion retaining walls.