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Journal : Journal of the Civil Engineering Forum

Geotechnical Investigation and Numerical Analysis of Rockfall in South Coast of Gunung Kidul Regency Odhi Attabik Illiyin; Fikri Faris
Journal of the Civil Engineering Forum Vol. 3 No. 1 (January 2017)
Publisher : Department of Civil and Environmental Engineering, Faculty of Engineering, UGM

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (719.704 KB) | DOI: 10.22146/jcef.26595

Abstract

On 17th of June 2015, rockfall occurred on the South Coast at Gunung Kidul Regency taking a few casualties. The preliminary investigation results concluded that many cliffs on the South Coast are dangerous, and there is a potential that similar events might happen in the future. Therefore, geotechnical investigation in order to plan mitigation action is necessary. Field investigations, laboratory work, and numerical modeling were employed in this study, focusing on Sadranan beach where the incident happened. Rock slope stability analyses by means two-dimensional finite element in both static and seismic conditions were conducted.  The investigation results show that both biological decay and wave erosion influence the rock slope instability. Moreover, the infilling material in rock joint has considerable effect on the stability of the slope. However, the results from numerical simulation suggested that potential failure was originating from the intact rock body instead of the plane of discontinuities. In the seismic condition, the slopes are more vulnerable and further mitigation action should be considered in the future. 
A Numerical Analysis of Landslide Movements Considering the Erosion and Deposition along the Flow Path Aminudin Syah; Teuku Faisal Fathani; Fikri Faris
Journal of the Civil Engineering Forum Vol. 5 No. 3 (September 2019)
Publisher : Department of Civil and Environmental Engineering, Faculty of Engineering, UGM

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (689.795 KB) | DOI: 10.22146/jcef.43808

Abstract

Landslides are one of the most frequent disasters which occur widespread in Indonesia. This disaster often causes damages and fatalities. One of the mitigations efforts to reduce potential loss is by predicting the area affected by landslide movement. This research developed a numerical model of landslide movement by incorporating the erosion and deposition laws along the flow path. This model improves the accuracy of the previous models which assume that landslide volume is constant without any consideration for the erosion and deposition. The governing equation of this newly developed model uses the Eulerian numerical approach based on the finite difference scheme. The erosion-deposition laws applied in this research are from Egashira et al. (2001), McDougall and Hungr (2005), and Blanc (2008). The simulation program applies Python programming language and examines an imaginary slope with ellipsoid-shaped of source area. The simulation result shows that the additional erosion-deposition formula can enlarge the volume and the affected area of landslide movement. It is clarified that the erosion rate is a determinant factor affecting the results of calculation.
Parametric Study of the Effect of Ground Anchor on Deep Excavation Stability Aditya Putra Pratama; Hary Christady Hardyatmo; Fikri Faris
Journal of the Civil Engineering Forum Vol. 6 No. 1 (January 2020)
Publisher : Department of Civil and Environmental Engineering, Faculty of Engineering, UGM

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (465.392 KB) | DOI: 10.22146/jcef.47514

Abstract

Apartment construction is mostly carried out by including deep excavation works. However, excavation causes land instability; hence, the work needs to be done by a particular handler. In some cases, deep excavation is carried out on soft soil, which has a very high level of soil instability; therefore, a specific handling method such as ground anchor is required as an alternative. This study aims to conduct parametric research on the effect of using anchors on the stability of deep excavation. First, anchors of various slopes were modelled while varying the number of anchors up to four pieces. From the results of the study, the requirements representing the most efficient use of anchors were selected, and then various anchor bond lengths were modelled. Finally, the effect of applying various magnitudes of prestress forces to the anchor was determined. All of the models were examined to determine the influence on the stability of the deep excavation by observing the horizontal displacement and the forces that occur on the secant pile. From the analysis results, it can be concluded that the most effective slope angle is 0°. The displacement and forces occurred in the secant piles on the use of two, three, or four anchors has not a significant difference. The application of a higher prestress force on the anchor would yield better results as long as it is not exceeding 200 kN. However, in the case of an apartment building’s plans in Surabaya, the optimal anchor usage was found to be the use of two anchors with a 45° slope, 4.5 m for the first (A) and second (B) anchor bond lengths, 15 m free length anchor, 2.5 m vertical anchor distance, 1.2 m horizontal anchor distance, and the application of 200 kN prestress force.