Pseudo-static slope stability analysis around the landslide at railway tunnel, South Sumatera, Indonesia

Abstract

On January 23rd 2016 there was a landslide in the Lahat-Lubuk Linggau railway, right at the mouth of the railway tunnel in Lahat Regency. About 5 meters thick of soil covered the railway, causing the railway to be stopped for several days. Since the tunnel was built in 1928 until landslides occur in 2016 which means it has been 88 years. The landslide can be caused by several factors, these factors are slope geometry, physical and mechanical characteristics of rocks or soil, geological structure, hydrology and hydrogeology, and external forces such as ground vibration due to railway traffic and earthquake. The results of research on the main causes of landslides in the mouth of the railway tunnel include relatively steep morphological influences, degradation of rock strength due to weathering, dip rock structure in the direction of slope, and ground vibration due to earthquakes. Based on field observations, the slope next to the case study area of the landslide is also unstable. Therefore, it is necessary to analyze the slope stability in the area that has the potential to landslide, using a pseudo-static slope stability analysis on the consideration of the effect of ground vibration due to earthquakes is quite significant to slope stability. The results of the pseudo-static slope stability analysis is showing out that the factor of safety is around 1.22-1.16 with a seismic coefficient of 0.10-0.125 g. To anticipate future landslide we suggest to be conducted studies on slope stabilization methods including building retaining walls, drainage channels and shotcrete walls.