Sriwijaya Journal of Environment P-ISSN: 2527-4961 E-ISSN: 2527-3809 67 Article History: Received: 29 August 2017 Accepteed: 5 November 2017 DOI: 10.22135/sje.2017.2.3.67-71 *Corresponding Author: moamar.ghadaf@gmail.com Efect of Ground Vibration to Slope Stability, Case Study Landslide on The Mouth of Railway Tunnel, Gunung Gajah Village, Lahat District Moamar Aprilian Ghadaf 1.* , Muhammad Taufk Toha 2 , Dedi Setiabudidaya 3 1 Mining Engineering, Faculty of Engineering, Sriwijaya University, Palembang 30319 2 Mining Engineering, Faculty of Engineering, Sriwijaya University, Palembang 30319 3 Physics, Faculty of Mathematics and Natural Science, Sriwijaya University, Palembang 30319 Abstract Slope stability around railway tunnel in Gunung Gajah Village, Lahat District needs to be analysed due to landslide which occurred on January, 23 th 2016. That analysis needs to be done so that the railway transportation system can run safely. The purposes of this research are: to fnd out the factors that cause slope instability, to fnd out peak acceleration caused by railway trafc and earthquakes and its efects to the safety factor of slope, and determine stabilization method in order to prevent the occurrence of further landslide. The research activ- ities include surveying, sampling, laboratory testing and analyzing slope stability using pseudo-static approach. Based on research result, the main factors that cause slope instability are morphology, structural geology, and ground vibration caused by earthquakes. Ground vi- bration are correlated to the slope instability. It shows that the higher of peak acceleration the lower of safety factor of slope. To prevent the occurrence of further landslide around research area, stabilization method should be applied in accordance with the conditions in that area such as building a retaining wall to increase safety factor of slope, building draining channels to reduce run of and performing shotcrete in the wall of landslide in order to avoid weathering. Keywords: ground vibration, slope stability, stabilization method Abstrak (Indonesian) Kestabilan lereng di sekitar terowongan kereta api di Kelurahan Gunung Gajah, Kabupaten Lahat perlu dianalisis sehubungan dengan terjadinya longsoran di lokasi tersebut pada tanggal 23 Januari 2016. Analisis tersebut perlu dilakukan agar sistem transportasi kereta api dapat berjalan dengan aman dan lancar. Tujuan penelitian yaitu mengetahui faktor - faktor yang mempengaruhi lereng menjadi tidak sta- bil, mengetahui percepatan puncak getaran tanah dan pengaruhnya terhadap kestabilan lereng, dan menentukan metode stabilisasi lereng untuk mencegah terjadinya longsoran selanjutnya. Kegiatan penelitian meliputi kegiatan survei, pengambilan sampel, uji laboratorium, dan analisis kestabilan lereng menggunakan pendekatan psedostatik. Berdasarkan hasil penelitian, faktor utama yang menyebabkan lereng tidak stabil adalah morfologi, struktur geologi, dan getaran tanah akibat gempa bumi. Getaran tanah akibat gempa bumi dan lalu lintas kereta api berbanding lurus terhadap ketidakstabilan lereng. Hal ini menunjukkan bahwa semakin besar nilai nilai percepatan puncak getaran tanah maka semakin kecil nilai faktor keamanan suatu lereng. Untuk mencegah terjadinya longsoran selanjutnya maka metode stabilisasi perlu diterapkan sesuai dengan kondisi-kondisi di lokasi tersebut. Metode stabilisasi yang dapat diterapkan, yaitu membangun dinding penahan (retaining wall) untuk menaikkan nilai faktor keamanan lereng, saluran drainase untuk mengurangi jumlah air limpasan dan melakukan penyemenan (shotcrete) pada dinding bekas longsoran untuk menghindari pelapukan. Katakunci: getaran tanah, kestabilan lereng, metode stabilisasi 1. Introduction On January 23 th , 2016 a landslide has occurred at the mouth of the railway tunnel in Gunung Gajah Village, Lahat District. At the time of the landslide occurred, fortunately, there was no train passing and the railway track could be cleared immediately from landslide. Landslide covering the railway track could be very dangerous if there was a train passing though the tunnel and could cause injuries and fatalities. Generally, the landslides are caused by several parameters such as geological structure, hydrogeology, geotechnical, land use, and ground vibration due to earthquake activity and rail trafc. Land- slides are more common occurred in the areas which have weak structures with slope of 35°. These structures greatly afect rock strength because they are weak areas in the rock or at least they are water seeps and this will accelerate weathering and generally the weak plane becomes a landslide. Next hydrology will cause a high degree of weathering. Hydrology afects the strength value of the material and decreases the efective normal pressure and resistance to shear strength. Then the physical properties of the soil or rock that afect the stability of the slope is the density (γ), while the mechanical properties are shear strength expressed by the cohesion (c) and internal friction angle (ϕ). Shear strength is a force that serves as a force to resist or resist the force of cause of sliding. Last but not least, ground vibration can contribute to the occurrence of landslide because the dynamic load from the ground vibration can increase the shear stress on the slope and increase the soil pore pressure so that the shear stress increases and the shear strength