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PETA RAWAN LONGSOR DESA NANGGERANG, KECAMATAN SUKASARI, KABUPATEN SUMEDANG, JAWA BARAT MENGGUNAKAN ANALISIS KESTABILAN LERENG TIGA DIMENSI Aruan, Immanuel Hareanto; Yuniardi, Yuyun; Khoirullah, Nur; Sophian, Raden Irvan
Bulletin of Scientific Contribution Vol 22, No 2 (2024): Bulletin of Scientific Contribution:GEOLOGY
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/bsc.v22i2.55505

Abstract

Pada tanggal 3 Februari 2024, terjadi longsor di Desa Nanggerang, Kecamatan Sukasari, Kabupaten Sumedang, Provinsi Jawa Barat. Longsor ini terjadi di lereng persawahan masyarakat setempat. Berangkat dari hal ini, dilakukan penelitian mengenai peta kerawanan longsor lereng lokal di Desa Nanggerang untuk memberikan informasi kepada masyarakat setempat mengenai potensi longsor yang ada. Penelitian dilakukan menggunakan analisis kestabilan lereng tiga dimensi (3D) dengan perangkat Rocscience Slide 3. Geometri lereng diidentifikasi menggunakan proses fotogrametri yang diakuisisi oleh pesawat nirawak. Sedangkan lapisan yang dibagi, yaitu top soil OH, tanah MH, dan batuan andesit terlapukkan, diidentifikasi melalui observasi lapangan dan uji laboratorium mengenai sifat fisik dan mekaniknya. Dengan memasukkan index properties ke dalam model 3D lereng hasil proses fotogrametri, perhitungan kestabilan lereng menggunakan metode Janbu dilakukan untuk mendapatkan peta rawan longsor di daerah penelitian. Hasil komputasi menunjukkan, lereng di Desa Nanggerang berada pada kondisi stabil pada kondisi kering (FK = 1,5). Sedangkan pada kondisi jenuh dan pseudo-statis lereng mengalami keruntuhan (FK <1). Oleh karena itu, disarankan untuk mengefisiensikan penggunaan lahan dan aliran pada persawahan guna mengurangi risiko terjadinya longsor.
PENURUNAN MUKA TANAH DI KOTA-KOTA BESAR PESISIR PANTAI UTARA JAWA (STUDI KASUS : KOTA SEMARANG) Sophian, Raden Irvan
Bulletin of Scientific Contribution Vol 8, No 1 (2010): Bulletin of Scientific Contribution
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/bsc.v8i1.55904

Abstract

ABSTRACTMajor cities in the north coast of Java developed in estuarine watersheds.  Genetically, sediment material scattered in the region.  Sediments of  weathering and erosion result,  is carried by a river sediment in the river estuaries.  Characteristics of the material-forming region, is dependent upon the crushed rock by river. Phenomenon of subsidence / land subsidence occurred in this many areas. Naturally, these regions experiencing land subsidence resulting from sediment material properties. This subsidence can be caused by various factors, for example due to soil load itself, so there is a decrease naturally. Consolidation is  included in the normal consolidation. Factors considered in knowing subsidence, is a load of soil itself on each layer of fine-clastic, so that can be known susidence due to overburden load. Within a certain timeframe land subsidence is still going to happen, especially in the northern part of  Semarang city (old city) which can be resulted in a tide flood so that it must consider its handling.  Keywords: alluvial, land subsidence, consolidation, overburden, tide flood ABSTRAKKota-kota besar di pesisir pantai utara Jawa banyak berkembang di daerah muara aliran sungai. Secara genetik, di wilayah tersebut tersebar material endapan aluvial. Endapan-endapan hasil  pelapukan dan erosi terbawa oleh air sungai yang mengendap di muara sungai. Karakteristik material  penyusun wilayah sangat tergantung oleh batuan yang digerus oleh sungai tersebut. Fenomena amblesan/ penurunan muka tanah  banyak terjadi di wilayah ini. Secara alami, daerah tersebut mengalami penurunan muka tanah akibat dari sifat material endapan aluvial. Penyebab terjadinya penurunan ini dapat diakibatkan oleh berbagai faktor, salah satunya akibat beban tanah itu sendiri, sehingga terjadi penurunan secara alami. Konsolidasi yang terjadi termasuk ke dalam normal konsolidasi.  Faktor yang diperhitungkan untuk mengetahui penurunan yang terjadi, adalah beban tanah itu sendiri pada setiap  lapisan klastika halus, sehingga dapat diketahui penurunan akibat beban overburden. Dalam jangka waktu tertentu penurunan muka tanah masih akan terjadi, terutama di kota Semarang bagian utara (kota lama) yang dapat mengakibatkan terjadinya banjir laut pasang sehingga perlu dipikirkan penanggulangannya.        Kata kunci: aluvial, land subsidence, konsolidasi, overburden, banjir rob
SLOPE STABILITY ANALYSIS USING FINITE ELEMENT METHOD (FEM) IN WARA OPEN PIT COAL MINE, PT ADARO INDONESIA, TABALONG, SOUTH KALIMANTAN Sihotang, Josua Washington; Bakhtiar, Taufiq; Khoirullah, Nur; Sophian, Raden Irvan; Zakaria, Zufialdi
Journal of Geological Sciences and Applied Geology Vol 3, No 3 (2019): Journal of Geological Sciences and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v3i3.25667

Abstract

The stability of slope is impacted by Rock Mass Rating, material properties, and slope geometry. Furthermore, the slope stability analysis was needed to know the slope stability condition. This research aims to know the Strength Reduction Factor (SRF) value by using Finite Element Method (FEM) using Hu=1 and Hu=Auto. The geotechnical mapping that is Rock Mass Rating (RMR) and Measured Section were done to get the Geological Strength Index (GSI) and profile of layer rocks in highwall slope SCT_J1 and SCT_J2. From the FEM analysis, actual slope SCT_J1 has the SRF=1.25 with Hu=1 and SRF=1.4 with Hu=Auto. SCT_J2 has SRF=1.21 with Hu=1 and SRF=1.3 with Hu=Auto. From the slope stability analysis, SCT_J1 and SCT_J2 were classified into stable slope due to the SRF value higher than 1.2.
ANALYSIS OF LANDSLIDE CAUSES IN NANGGERANG VILLAGE, SUKASARI SUB DISTRICT, SUMEDANG REGENCY THROUGH IDENTIFICATION LANDSLIDE SLOPE MATERIAL CHARACTERISTICS Aruan, Immanuel Hareanto; Yuniardi, Yuyun; Khoirullah, Nur; Sophian, Raden Irvan
Journal of Geological Sciences and Applied Geology Vol 8, No 1 (2024): Journal of Geological sciences and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v8i1.56627

Abstract

On February 3, 2024, a landslide occurred in Nanggerang Village, Sukasari District, Sumedang Regency, West Java Province. The landslide took place on the slopes of local farmland. This event was investigated through an analysis of the characteristics of the landslide material collected immediately after the landslide to determine its cause and mechanism. The landslide slope was divided into three units based on the type and degree of weathering: topsoil (OH), silt soil (MH), and weathered tuff rock. Three undisturbed samples were used in laboratory experiment to determine the materials’ physical characteristics. The physical characteristics of the two soil units, which included silt-sized grains, a specific gravity of roughly 2.6, a unit weight ranging from 21 to 45 kN/m3, and a plasticity index of 16 to 20, were not substantially different, according to the results of the laboratory tests. For the tuff rock, the unit weight was 17.31, water content 48.8, and specific gravity 22.7. The laboratory test results, and studio analysis found that the high water content in the soil due to rainfall caused the two soil units to exceed their liquid limit, resulting in a translational (arc) landslide. The presence of clay minerals due to weathering acted as a catalyst for the landslide. The addition of water from heavy rainfall made the material more fluid, changing the type of landslide to an earth flow.
Analysis of Physical and Mechanical Properties of Andesite Lava Geulis Mountain Area, Jatinangor, West Java Abdullah, Fajar; Sophian, Raden Irvan; Khoirullah, Nur; Zakaria, Zufialdi; Asykarulloh, Abdul Wahid; Taufiq, Mochamad Muslim; Shafira, Nisa; Putri, Revena Denia
Journal of Geological Sciences and Applied Geology Vol 5, No 1 (2021): Journal of Geological Science and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v5i1.34851

Abstract

Jatinangor is an area composed of material from volcanic activity, one of the results of volcanic activity is andesite rock. The purpose of this research is to provide information related to the physical and mechanical properties of the lava rock in the Gunung Geulis area so that if there is construction work or rock utilization there is already information about the characteristics of the rock. The method used in this study is a laboratory experiment by conducting tests on 9 selected rock samples. The results of laboratory testing can be concluded the rock in the research area is andesite rocks and have rock physical properties namely Natural density (1.5 – 1.6 gr/cc), Saturated density (1.6 – 1.7 g/cc), Dry Density (1.5 – 1.6 g/cc), Bulk Saturated Surface Dry (SSD) Specific Gravity (2.3 – 2.4), Apparent Specific Gravity (2.5 – 2.7), absorption (3 – 5.9%), Natural moisture content (0.6 – 2.3%),  Porosity (4.9 – 9.4%) and the mechanical properties of the rock, namely the compressive strength of the rock, ranged from 33,099 – 85,096 Mpa. Based on the results and analysis, the mechanical properties of rocks, namely the compressive strength of rocks in the study area, have varying values and varied physical properties of rocks. Physical and mechanical properties of rocks that are correlated based on linear correlation are the compressive strength of rocks with absorption, Natural moisture content, and porosity. These parameters will show the relationship that can affect the compressive strength of rocks. So that when using rock in construction work, mining, the use of rock needs to pay attention to the compressive strength or mechanical properties and physical properties of the rock.
Liquefaction Potential based on Earthquake History in Sanana Region, Sula Island Regency, North Maluku, Indonesia Pajrin, Ulfia Sari; Zakaria, Zufialdi; Sophian, Raden Irvan; Khoirullah, Nur; Mubarak, Aziez; Basuki, Jodi Prakoso
Journal of Geological Sciences and Applied Geology Vol 3, No 1 (2019): Journal of Geological Sciences and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v3i1.21947

Abstract

Sula Islands is a region in Maluku Province that is very vulnerable to earthquakes because it is located on an active seismic line. One of the disasters that often accompanies earthquakes is liquefaction. Sandy soil in a saturated condition will lose its strength when an earthquake occurs, thus endangering the building above it. The aim of the study was to determine seismicity and estimate the liquefaction potential of the earthquake history and CPT test in the Sanana region and its surroundings. The method in this study uses a "simplified procedure" method for evaluating liquefaction resistance of soils. 2 main parameters were sought in this study, CSR obtained based on tectonic conditions and a history of seismicity and CRR obtained from the results of CPT testing. The results showed that seismicity in the Sanana region was sourced from Sula-Sorong active fault activity with a history of the greatest magnitude of 8.1 and 7.7. As for the calculation results from CPT data, the Sanana area has the potential for liquefaction of sand medium material at a depth of 5-12 m for earthquakes with magnitude 7.5 and 4 -12 m in magnitude 7.7 and 8.1. The potential for liquefaction in this area is caused by the type of saturated medium sand material and this location which is close to the active fault activity of Sula-Sorong. Therefore, it is necessary to evaluate the potential for liquefaction in planning, building and developing infrastructure in earthquake-prone areas so that disasters of liquefaction can be prevented.
SIMULATION OF OPD WASTE DUMP SLOPE USING THE MORGENSTERN-PRICE METHOD IN WORK AREA OF PT. XYZ TBK. PASER DISTRICT, EAST KALIMANTAN PROVINCE Audrey, Lizzy Evsa; Sophian, Raden Irvan; Hadian, Sapari Dwi
Journal of Geological Sciences and Applied Geology Vol 7, No 1 (2023): Journal of Geological Science and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v7i1.48280

Abstract

The research was conducted at a company working in the coal mining contract sector, namely PT. XYZ Tbk. OPD is located in Paser Regency, East Kalimantan. The research aims to create a slope simulation for analysis. This analysis is used to determine the safety value factor with the influence of the parameters used, with reference to the safety value factor based on safe slope criteria according to KEPMEN ESDM Number 1827 K /30/MEM/2018. Parameters in the simulation are material properties in the form of unit weight, cohesion and internal friction angle. The material used is bedrock material in the form of sandstone, and overburden material in the form of a mixture of sandstone and claystone. Engineering is carried out by considering the condition of the groundwater table, namely full saturation and the earthquake vibration coefficient, to be analyzed using the Morgenstern-Price method. The safety factor value that has been obtained in the slope simulation is 1,216, the safety factor value includes unsafe slopes which are affected by groundwater conditions and earthquake vibrations.
Erosion Potential Based on Erodibility Factors In Cimanggung And Surrounding Region, Sumedang Regency, West Java, Indonesia Rahmi, Nisa Shafira Muthia; Sophian, Raden Irvan; Khoirullah, Nur; Zakaria, Zufialdi
Journal of Geological Sciences and Applied Geology Vol 5, No 2 (2021): Journal of Geological Science and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v5i2.34661

Abstract

The research area around Gunung Geulis has been shifted from agricultural land into residential areas. This transformation eventually will affect the water infiltration process especially throughout the rainy season and can cause the intensity of the erosion rate to go higher. Soil erodibility is defined as the susceptibility of the soil to erosion, as the degree to which a soil is easily eroded or not. This research was conducted to determine the erodibility value in an area of ± 25 km2 which administratively belongs to the Districts of Cimanggung and Jatinangor, Sumedang Regency, West Java Province. The erodibility value can be calculated by the method introduced by Wischmeier and Smith (1978) and it is determined based on several parameters, namely texture of the soil, soil structure, permeability value, and organic (%C) content in a soil sample. The research data was obtained by engineering geological mapping of the distribution of surface soil, taking undisturbed soil samples using the hand auger method, and laboratory tests in the form of testing the physical properties of the soil. Then several laboratory tests are conducted to identify the physical properties of soil such as organic (%C) content analysis using Walkley and Black method, grain size analysis, hydrometer analysis, and permeability analysis using the falling head method. In the research area, the soil type is divided into two units, namely the Low Plasticity Silt Unit and the High Plasticity Silt Unit. Soil erodibility values around Gunung Geulis ranged from 0.118 to 0.514 0,1-ton acre hour/acre foot-ton inch which was included in the classification of a low, medium, moderately high, and high erodibility levels according to US customary dimensions.
Slope Stability Analysis on Muaraenim Formation, South Sumatera, Indonesia Ulhaque, Thaha Rizal; Khoirullah, Nur; Sophian, Raden Irvan; Zakaria, Zufialdi
Journal of Geological Sciences and Applied Geology Vol 3, No 2 (2019): Journal of Geological Sciences and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v3i2.23206

Abstract

Slope stability analysis is a necessary aspect in open mining operations. The research location is in the Muaraenim Formation, South Sumatra, Indonesia. In this study, the level of slope stability is determined by the value of the Safety Factor (FS). The method used is limit equilibrium, the Spencer method. The results of this study indicate that FS values are influenced by the angle of the slope, where with decreasing degree of slope, the FS value will increase. In addition, the FS value is also directly proportional to the cohesion value of the slope materials.
SWELLING POTENTIAL OF CLAY SOIL KALIWANGU FORMATION IN CIBOGO DISTRICT, SUBANG REGENCY AREA BASED ON ITS BASIC PHYSICAL PROPERTIES Prasetio, Rio Akmal Rizky; Sophian, Raden Irvan; Firmansyah, Yusi; Khoirullah, Nur
Journal of Geological Sciences and Applied Geology Vol 7, No 2 (2023): Journal of Geological Sciences and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v7i2.49958

Abstract

The research is conducted in Cibogo District, Subang Regency. Focus of the research is taking samples in area inside Kaliwangu Formation by doing field observation and field sampling using disturbed sample method then it will be tested in laboratory for its basic physical properties. Result of its basic physical properties will be analyzed to determine their swelling potential by taking 5 sample of soil from Kaliwangu Formation. Based on sieve analysis every sample of Kaliwangu Formation (Pk) have more than 50% of clay fraction for each sample, and based on Atterberg limit test Kaliwangu Formation (Pk) samples are dominated by Silt High Plasticity (MH) soil with 3 samples of the MH type and only 2 samples of the CH type. According to consistency limit test of Kaliwangu Formation (Pk) soil, the swelling potential can be determined by classify it based on liquid limit (%) and plasticity index (%) using swelling potential classification. Using the soil consistency value, especially the liquid limit value and the plasticity index value, it can be classified as the swelling potential of Kaliwangu Formation (Pk) classified as high - very high potential with a very high dominance.