Abstract.A nationwide Vs 30 map for Indonesia was developed based on automated topographic classification from 90-m grid digital elevation data and their correlation with Vs 30 . Automated topographic classification has been proposed by Iwahashi and Pike (2007) and a procedure to convert topographic class into Vs 30 maps has been developed by Imamura and Furuta (2015) based on Vs data from J-SHIS (Japan Seismic Hazard Information System). In order to be suitable for Indonesia, calibration work according to Imamura and Furuta's procedure should be conducted since the geotechnical conditions in Japan may not be the same as in Indonesia. This paper presents adjustment of the Vs 30 correlation by Imamura and Furuta to convert topographic class into Vs 30 and construct a Vs 30 map of Indonesia. This correlation was calibrated by using Vs data from BMKG (Indonesian Agency for Meteorological, Climatological, and Geophysics) as well as standard penetration test logs that were collected by the authors. Utilization of local field measurement data will certainly enhance the reliability of the Vs 30 map. The developed nationwide Vs 30 map will be very useful for disaster mitigation programs and for preliminary design of earthquake resistant buildings and infrastructure in Indonesia.

Aceh Province is one of the coal producers, especially Sumber Batu Village in Meurebo District, West Aceh Regency. In the implementation of coal mining, it is necessary to pay attention to the slope stability of open-pit mining to identify and estimate the possibility of landslides. For this reason, the author conducted research in analyzing the geometric shape of the slope stability with the slope variance of modeling the reduction of the existing angle αeks - 10% to the depth of three layers of soil 11 meters. The 1st layer of soil is 1.5 meters, the second layer of soil is 2.5 meters, and the third layer of soil is 7 meters. Slope stability is strongly influenced by the geometric shape of the slope and the strength of soil parameters. To identify the stability of the slope against slope failure, computationally performed using the finite element method with Plaxis software as the reference for the value of FK 1.25, which is considered safe/stable, meaning that collapse rarely occurs. In this research, primary data is used in the form of direct observation in the field, namely taking soil samples to obtain soil data in the form of soil physical properties and soil mechanical properties into soil parameter data, which is tested in the soil laboratory. Secondary data used are map data, boring data, and Sondir data. Soil parameter data were processed using Plaxis software. The results of the slope stability analysis showed that by modeling the geometric shape of the slope (αeks - 10%) on the open slope of a coal mine with a soil depth of 11 meters, the FK value was 3.60. From the results of the FK scores, it shows that the slope of the slope is 3.60 1.25 above the reference value of safe/stable FK. The FK value is 0.2 greater than the FK existing geometry. The conclusion of this study is that geometric shapes play an important role in determining the stability of an open coal pit excavation slope. The smaller the slope angle, the greater the FK value obtained, or the more gentle the slope, the higher the safety value of a slope.

Clay soil from Desa Meunasah Rayeuk quarry in Kaway XVI,  West Aceh Regency is a land material frequently used for construction of road infrastructure. In this quarry, there are three types of soil based on the color, yellow, red, and gray. The three types of soil have expansive characteristics, so they are not suitable for subgrade.  This unoptimal characteristic can be improved through soil stabilization. One of them by utilizing the reaction of catinonization between lime Ca(OH)2 with the clay soil. Therefore, a research needs to be conducted to find out the characteristics of physical and mechanical properties of the original soil and the effect of cationization of the soil and lime mixture on the soil plasticity index and soil shear strength parameters. Testing is done through mineralogical test and ASTM standard tests that include physical properties, standard compaction, and direct shear strength test. Variations of lime addition are 0%, 3%, 6%, 9%, and 12% of the soil dry weight. The test results show that the addition of lime can reduce the soil plasticity index and increase the shear strength of the soil on some level. At mixing up to 12% lime, the soil plasticity index dropped to 12.93% in yellow clay, 11.12% in red clay, and 16,76% in gray clay. The plasticity index after the addition of 12% lime has not met the minimum plasticity index requirement, ie 11%. The maximum shear strength for yellow clay is obtained at 3% lime, and 6% lime for red and gray clays.

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Road infrastructure is very important and is a key enabler for the economy. If the road infrastructure was damaged or had various problems such as sliding, the movement of goods and passengers will be hampered and delayed to the acceleration of development in the local area. The landslide and movement of groundwater is a problem that often occurs repeatedly on some streets. Therefore, it is necessary to study the strengthening of the slopes at the bottom of the road construction with retaining wall. This study aims to analyze slope stability by getting numbers Safety Factor (FK). The analysis is used to analyze the stability of slopesusing the finite element method with the help of software Plaids, The scope of this review includes the calculation of slope stability at the national road from Banda Aceh - Medan Sta. 83 + 185 Mount Selawah. The results of slope stability analysis on the existing condition by using Plaxis software at the point of a review is not safe (FK 1.25). Thus, it is done handling the retaining wall, installation of anchors. Based on the analysis of slope stability after being given the strengthening of the slopes with a retaining wall and the installation of anchors using Plaxis software under the influence of traffic load in an unsafe condition (FK 1.25). Then additional handling is done by changing the angle of the slope so that the value of the safety factor (FK) 1.25.