Process of rain-induced landslide in tropical soils in Indonesia :: Case study on Slope at Km 15.9 of Kalibawang irrigation channel, Kulon Progo Regency, Yogyakarta Special Province

VEASNA, Long, Ir. Dwikorita Karnawati, M.Sc.,Ph.D

2005 | Tesis | S2 Teknik Geologi

Kalibawang Irrigation Channel has been found to be threatened by landslide risk in every rainy season. Among many types of slope movement ever found, slope creeping is the most devastating hazard to the infrastructures and the private properties. In the case of slope at Km 15.9, which is located in Mejing village of Kulon Progo Regency, Yogyakarta Special Province, the continuously slow slope movement is suspected to induce additional stress on the bridge and the channel bridge downhill to deform in every rainy season. To help solve that problem, this research is conducted to understand the process of that slope failure with special consideration given to the local climate and geology. Field investigation, laboratory testing, and field performance monitoring are utilized to investigate the site characteristics and to monitor the spatial and temporal slope behaviors. Numerical analysis, consisting of modeling of slope hydrogeological process and slope stability analysis, is used to enhance or add to the engineering judgment on that process. As a result, slope stratigraphy and slope materials are found to have a very important role in controlling the building up of pore-water pressure inside the slope. Rainfall, the role of which is to bring water to slope, is the main factor in triggering slope movement. Then, this movement causes the bridge and the channel bridge at the foot of slope to deform gradually. When the primary cause of structural damages is clearly understood, suggestions can be effectively made to remedy the undesirable effect or to minimize the risk. Yet, providing specific method(s) to cure this problem is beyond the scope of this research work.

Kata Kunci : landslide, slope creeping, process of rain-induced landslide, field performance monitoring, numerical analysis