Fahrudin Fahrudin
Program Studi Teknik Geologi, Fakultas Teknik, Universitas Diponegoro, Jl. Prof. Soedarto, SH, Kampus Undip Tembalang, Semarang 50275

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Journal : Geological Engineering E-Journal

PENGARUH SEEPAGE DAN KESTABILAN LERENG TERHADAP OPTIMALISASI GEOMETRI LERENG TAMBANG BUKIT M AIR LAYA BLOK TIMUR, UNIT PERTAMBANGAN TANJUNG ENIM Ariana, Diana; Pudjihardjo, Henarno; Fahrudin, Fahrudin; Tunggal, Joko
Geological Engineering E-Journal Vol 6, No 1 (2014): Volume 6, Nomor 1, Tahun 2014
Publisher : Geological Engineering E-Journal

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Abstract

Kestabilan lereng merupakan salah satu hal terpenting dalam proses eksploitasi tambang batubara. Diperlukan penyelidikan geoteknik dalam perancangan desain yang aman dan efektif sehingga penambangan batubara dapat dioptimalisasikan. Daerah penelitian dilakukan pada tambang Bukit M Air Laya Blok Timur Unit Pertambangan Tanjung Enim. Lokasi tambang ini berada disebelah barat sungai, penelitian ini dimaksudkan untuk mengetahui pengaruh pola aliran dan kestabilitan lereng dalam optimalisasi geometri lereng.Metode penelitian yang digunakan adalah dengan cara melakukan interpretasi data log bor  untuk mengetahui karakteristik tiap lapisan penyusun daerah tersebut meliputi data permeabilitas, kohesi, sudut geser serta bobot isi yang nantinya akan diolah menggunakan software Geoslope Seep/w dilakukan untuk mengetahui seberapa besar debit yang akan merembes dan Geoslope Slope/w dilakukan untuk mengetahui nilai faktor keamanan suatu lereng.Analisis rembesan terhadap kestabilan lereng dimodelkan dengan 2 penampang dengan jarak boundary tambang dari sungai yaitu 100m. Dua penampang memiliki elevasi tambang dibawah sungai Enim yaitu penampang C-C’ menghasilkan debit sebesar 3.186e-08 m3/s, penampang D-D’ menghasilkan debit sebesar 4.768e-08 m3/s. Analisa Slope/w dihasilkan Fk Penampang C-C’ = 1.754 (Stabil) Penampang D-D’= 2.509 (Stabil). Penampang E-E’ =2.310 (Stabil). Untuk desain pelebaran lereng /boundary tambang dilakukan pula analisa kelerengan pada lereng utara dan selatan sebanyak 3 penampang dihasilkan Fk penampang G-G’ memiliki FK 1.992 (U) dan 1.583 (S). penampang H-H’ 1.855 (S) dan penampang I-I’ 1.608 (U) dan 1.904 (S). Dari hasil kajian optimalisasi pelebaran dengan jarak 100 m dari Sungai Enim ke boundary tambang memiliki FK overall slope > 1.72 dengan pengaruh pola aliran dari sungai ke tambang maupun tambang ke sungai dikategorikan tidak terlalu besar sehingga pada daerah ini layak untuk diperlebar atau dioptimalkan.
ANALISIS SENSITIVITAS PEMODELAN ANALOG SANDBOX UNTUK MENGETAHUI PERKEMBANGAN STRUKTUR SESAR NAIK Asmarakandy, Dimas; Suprapto, Dwiyanto Joko; Fahrudin, Fahrudin
Geological Engineering E-Journal Vol 6, No 2 (2014): Wisuda Periode Juli - Oktober 2014
Publisher : Program Studi Teknik Geologi, Fakultas Teknik, Universitas Diponegoro

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Abstract

Pemodelan sandbox adalah salah satu jenis pemodelan analog dalam ilmu geologi yang memiliki tujuan utama yaitu simulasi gaya, deformasi dan evolusi struktur cekungan sedimen. Terbentuknya struktur geologi berupa sesar naik (thrust atau backthrust fault) diakibatkan oleh sistem tektonik konvergen dan dapat dimodelkan dengan pemodelan sandbox. Penelitian ini bertujuan untuk memahami mekanisme dan sekuen deformasi dari sistem sesar naik dengan mengetahui hasil deformasi yang berupa pola struktur geologi; mempelajari perkembangan morfologi, pola dan distribusi struktur pada sistem tektonik konvergen; mengetahui variabel pengujian dalam pembentukan deformasi pada pemodelan sandbox. Penelitian dilakukan dari tahap persiapan hingga pelaksanaan. Persiapan yang dilakukan adalah pewarnaan, pengeringan dan pengayakan bahan model yaitu pasir kuarsa Formasi Ngrayong dengan dua macam ukuran butir; kategori ukuran pasir kasar (30-50 mesh) dan kategori ukuran pasir halus (60-80 mesh). Selanjutnya melakukan uji konsistensi alat sandbox. Hingga terakhir menentukan kondisi batas pemodelan seperti ukuran butir, ketebalan dan basement. Pada tahap pelaksanaan, data yang dihasilkan yaitu; foto/ gambar hasil pemodelan, waktu pergerakan dan jumlah sesar yang terbentuk, jarak pemendekan dan perubahan dip sesar, serta perkembangan morfologinya. Struktur yang terbentuk yaitu thrust dan backthrust fault. Morfologi yang terbentuk merupakan sabuk sesar thrust yang perkembangannya ditandai oleh terbentuknya struktur-struktur sesar baru. Jumlah sesar bertambah dan sudut kemiringan sesar pun cenderung bertambah seiring dengan meningkatnya pemendekan. Semakin tebal lapisan pasir maka jumlah sesar yang terbentuk lebih sedikit sebaliknya semakin tipis lapisan maka jumlah sesar yang terbentuk lebih banyak. Perbedaan ukuran butir material akan menghasilkan pola struktur dan jumlah sesar yang berbeda pula.
ANALISIS FASIES DAN PERMODELAN SIKUEN STRATIGRAFI BATUAN KARBONAT LINTASAN KORIDO, FORMASI WAINUKENDI, KABUPATEN SUPIORI, PAPUA Shima, Joshua; Nugroho, Hadi; Fahrudin, Fahrudin; Permana, Asep Kurnia
Geological Engineering E-Journal Vol 6, No 1 (2014): Volume 6, Nomor 1, Tahun 2014
Publisher : Geological Engineering E-Journal

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Abstract

Korido is located in Supiori District , Papua , Indonesia . This area is in the north of the Central Range and included in the North Irian Basin which is the fore arc basin (Mc Adoo & J.C. Haebig, 1999). Own research area based on geology map created by Masria et al ( 1981) composed by Wainukendi Formation which is composed predominantly by carbonate sedimentary rocks .The purpose of this study is to determine the pattern of lithology and lithological boundaries were obtained from measured stratigraphy along the trajectory of research which is then integrated with the micro facies analysis and facies zone were obtained by petrographic analysis to determine the depositional environment and depositional processes that occur in Wainukendi Formation. More over, the relative age determination is also done based on the analysis of large benthic foraminifera so the deposition process can be integrated with relative age . The ultimate goal of this research is to integrate field data, micro facies analysis results and deposition process analysis results to create a model of sedimentation, determining stratigraphic marker, and the determines system tract that develops in Wainukendi Formation in the study area .The method used in this research is geological mapping focused on stratigraphy subjects in Korido area to get  lithostratigraphy sequence, platform type, sedimentation processes, and laboratory analysis include petrographic analysis to determine micro facies and facies zone and paleontological analysis to determine the relative age which then integrated to obtain stratigraphic marker and systems tract that develops in Wainukendi Formation. From the analysis of platform type showed the type of platform existing in this area is rimmed shelf type which is then used as a reference in micro facies analysis according to Wilson (1975) to obtain 4 facies zone that exist in this study area is reef platform margin , slope , toe of slope apron and deep shelf . Based on the analysis of the deposition process obtained 3 cycles of sedimentation that occurred from Wainukendi Formation . From the results of this analysis are used in determining the stratigraphic sequence to obtain stacking patterns that evolve based sequence boundary and its systems tract is composed of LST - TS - MFS - TST - HST so that obtain a full cycle changes in accommodation space and sediment supply where there is an increase in accommodation space which was offset by an increase in the supply of sediment in LST phase is characterized by progradation and agradation, an increase in the supply of sediment is lower than the increase in accomodation space in TST phase is characterized by retrogradation, and lastly, a decrease in accommodation space while sediment supply rate is still high in HST phase characterized by progradation.
EVALUASI GROUTING PADA SECTION RETAINING WALL – B (DOWNSTREAM) DI KALI SEMARANG, KELURAHAN PANGGUNG LOR, KOTA SEMARANG, JAWA TENGAH Asbella, Khalaksita Amikani; Suprapto, Dwiyanto Joko; Fahrudin, Fahrudin; Ningtyas, Citra
Geological Engineering E-Journal Vol 6, No 1 (2014): Volume 6, Nomor 1, Tahun 2014
Publisher : Geological Engineering E-Journal

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Abstract

Kali Semarang is one of the watering pattern that was in Semarang, Central Java, which runs from Pandanaran heading north toward the Java Sea. At the time of Semarang and surrounding areas have a condition that there are no rocks exposed at the surface because it is an area of older alluvium and river stage consisting of loose material such as clay, so this area has soft soil conditions until very soft. Lowering occurs in the area of construction of the embankment caused by the soft soil in the area around the construction of the embankment. Judging from the condition of the soil is soft and very soft, so we must be careful in determining the appropriate and correct methods for prevention of ground movement. Based on the soil conditions in the area of Kali Semarang, a study was undertaken using data SPT (Standard Penetration Test) to see the condition of the soil strength, and then to increase the strength of the soil used a method which is the method of grouting.From the results of drilling conducted at the Gate House point E1 +10 m, known at depth 0-2 m of sand sized loose gravel gray. At a depth of 2-20 m in the form of clay sized soft to very soft with gray. From SPT test data at Gate House point E1 +10 m, obtained N - SPT values <2 (very soft) at a depth of 2.8 to 5.8 m and a depth of 10.4 to 11.7 m. 2-3 N - SPT values (soft) is at a depth of 7.8 to 8.8 m and a depth of 13.4 to 19.3 m. SPT N - values (very dust) contained in an area close to the surface that is at a depth of 1.4 m.Once implemented method of grouting on Retaining Wall section B point 13 +1 m, +2 m point C10, and C18 +2 m point, a change in the value of the SPT test that the higher the value of N-SPT 4 (very dust) its value changed to 10 -15 (rather dense). N-SPT value of 0-1 (very soft), and the N-SPT values 2-3 (soft) turned into a N-SPT values 3-4 (soft), the value of N-SPT 5-7 (firm,) and N-SPT values 8-13 (stiff). To pile foundation bearing capacity changes from 16.57 tons to 35,98 tons to 53,03 tons. From the results of this investigation obtained good results for the purpose of grouting method successfully to increase the carrying capacity of the soil at the study site.Judging from its success with the implementation of the construction of grouting method can be resumed because the carrying capacity of the land has allowed it to withstand the load of the building to be erected.
ANALISIS PROVENANCE, DIAGENESIS DAN LINGKUNGAN PENGENDAPAN SERTA PENGARUH TERHADAP KUALITAS RESERVOIR BATUPASIR FORMASI TALANG AKAR, SUMUR FA-21, CEKUNGAN JAWA BARAT UTARA Abdillah, Fahmi; Nugroho, Hadi; Fahrudin, Fahrudin; Priyantoro, Agus
Geological Engineering E-Journal Vol 6, No 2 (2014): Wisuda Periode Juli - Oktober 2014
Publisher : Program Studi Teknik Geologi, Fakultas Teknik, Universitas Diponegoro

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Abstract

The necessary of technology at this time resulted the necessary of energy resources will increasing, and it also result the scarcity of energy resources. One of the energy resources that is still used as a major energy resource is oil and gas. To overcome these problems, exploration activities at this time needs to be further improved. In the field of exploration, one of the most important things to know is reservoir. Reservoir quality is important for us to know so that we can determine whether an area has hydrocarbon potential to be developed or not. The main parameters of reservoir quality are porosity and permeability.In this study discussed the analysis of provenance, diagenetic and depositional environment of the sandstone reservoir of Talang Akar Formation, North West Java Basin and from the results of the analysis will be associated with the effect on reservoir quality. To determine the reservoir quality based on these parameters, can be done by several methods such as petrographic, cores, SEM and XRD analysis. From the analysis that has been done can be seen that the provenance of Talang Akar sandstone is Granite. So it can be seen that the Talang Akar sandstone which the provenance is Granite has good reservoir quality, with porosity values ranging from 19.04% to 24.28% and permeability ranging between 30-674 mD or belonging to the class good - very good (Koesoemadinata, 1980). Then the diagenetic process that occurs is compaction, cementation, replacement and dissolution. The process of compaction, cementation and replacement leads to reduced rock porosity values ranging from 2.25 to 11.5%, while the dissolution process resulting in increased rock porosity is about 1.5 - 2%. The depositional environment of the Talang Akar Sandstone is Upper Delta front. Rock facies in the upper delta front has good reservoir quality, with porosity values range from 19.04% to 24.28% and permeability range between 30-674 mD or belonging to the class is good - very good (Koesoemadinata, 1980). 
EVOLUSI TEKTONIK DI DAERAH NENAS DAN KEFAMENANU, NUSA TENGGARA TIMUR IMPLIKASINYA TERHADAP POTENSI PERANGKAP (TRAP) HIDROKARBON PADA CEKUNGAN TIMOR BAGIAN BARAT Alfiansyah, Arif; Nugroho, Hadi; Fahrudin, Fahrudin; Wahyudiono, Joko
Geological Engineering E-Journal Vol 6, No 1 (2014): Volume 6, Nomor 1, Tahun 2014
Publisher : Geological Engineering E-Journal

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Abstract

In Timor island found many indications of hydrocarbons such as oil seeps, gas seeps and mud volcanoes. In the eastern part of the territory there are indications of more oil, while in the western part of the territory more gas indications (Charlton, 2001). It is a challenge for a geologist in particular to uncover all the potential that exists in the Timor Basin.The purpose of this study was to determine the composition of the stratigraphy in the study area, which is developing the geological structure and its relationship with the existing stratigraphy in the study area, the main emphasis is to work towards the western part of Timor Island, Explaining the tectonic evolution of the study area and type of trap hydrocarbons that exist in the study area.The method used in this thesis is a survey method and analysis methods. Methods of geological mapping survey with a description of the characteristics of each formation encountered and measured thick layer of rock that is useful for stratigraphic cross sections, and measurement of structural elements such as bedding plane, joint, faults and folds. Analysis method by analyzing both the geological structure alignment analysis and analysis stereografis.The composition of the regional stratigraphic in research area from old to young is Maubise Formation, Atahoc Formation, Cribas Formation, Niof Formation, Babulu Formation, and Aitutu Formation. Geological structures that developed in the study area at Permian old rocks there are a reverse fault has trending NW-SE, strike slip fault has trending N-S, and normal fault has trending NW-SE, whereas in Triassic old rocks there are a reverse fault has trending NE-SW, strike slip fault has trending NE-SW, and normal fault has trending NE-SW. Look at the similarity of has  trending reverse fault and normal fault orientation at Permian age, interpreted that reverse fault is result of reactivation from normal fault plane with same plane orientation. This also applies to Niof Formation, Babulu Formation and Aitutu Formation are Triassic old rocks there are a reverse fault has trending NE-SW and normal fault has trending NE-SW. the similarity of that trending orientation can interpreted as a result from reactivation of that happened at Permian old rocks. The main stress in Permian old rocks is NE-SW, while in Triassic old rocks is E-W. Based on analysis, trap hydrocarbon potential is structural trap with type are anticline and reverse fault 
REKONSTRUKSI STRUKTUR GEOLOGI DAERAH SUPIORI TIMUR – SELATAN, KABUPATEN SUPIORI, PULAU BIAK, PAPUA Rumanda, Fadlillah; Hidajat, Wahju Krisna; Fahrudin, Fahrudin; Wahyudiono, Joko
Geological Engineering E-Journal Vol 6, No 2 (2014): Wisuda Periode Juli - Oktober 2014
Publisher : Program Studi Teknik Geologi, Fakultas Teknik, Universitas Diponegoro

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Abstract

Papua and Papua New Guinea are had geology condition are very complex involving interaction between two plates, the Australian Plate and the Pacific Plate. New Guinea formed the result of the movement of oblique convergence (convergence oblique). The products of convergence are shrinkage and formed strike-slip structures and subduction which occur in Papua on 10 Ma. Sorendiweri Strait seen horizontal and vertical fault motion that separated the Biak Island and Supiori Island thar can be identified with the alignment on the satellite image.The purpose of this study was to determine the geological conditions in the study area, the pattern of structures, the main stress that formed the geological structure and reconstruct of geological structures in the study area. The Field research methods are field observation on Supiori track. Record the characteristics of the rock on each formation, measurement of geological structures such as bedding plane, joint and fault plane. Analysis methods such as analysis of alignment manually and visually interpreted on a satellite image DSM (Digital Surface Map). Stereographic analysis of geological structures, combining field data and analysis of alignment to determine the type of structure zone with rotated stress analysis and subsidiary structures method.Geological conditions consist of Oligocene clastic limestone Wainukendi Formation. and Miocene non-clastic limestones Wafordori Formation. Pattern geological structure on Wainukendi Formation., NE-SW normal faults, WSW-ENE strike-slip faults and NE-SW thrust fault. Wafordori Formation., NE-SW normal faults, NE-SW thrust fault. N-S trending major stress is the main primary stress, NE-SW and NW-SE sharpness trending are local stress. Reconstruction of geological structures of the study area began with N-S primary stress that formed E-W Maru reverse fault, NE-SW Soren sinisral fault and NW-SE Maruu, Yondonkir, Maryadori, Biniki dextral fault. The NE-SW trending secondary stress formed NW-SE Kepudari thrust fault, Yon reverse fault and Donkir reverse fault at south of the study area. 
KAJIAN POTENSI BAHAN GALIAN PASIR – KERAKAL DI SUNGAI BARO, KABUPATEN PIDIE, PROVINSI NANGGROE ACEH DARUSSALAM Zaenurrohman, Januar Aziz; Suprapto, Dwiyanto Joko; Fahrudin, Fahrudin
Geological Engineering E-Journal Vol 6, No 1 (2014): Volume 6, Nomor 1, Tahun 2014
Publisher : Geological Engineering E-Journal

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Abstract

The necessity of sand gravel in the development is become larger along with the advance of economic and population growth. Baro river has big enough natural resources in the form of excavated materials such as sand and gravel. Because of that reason, the stock taking of sand and gravel materials is needed in Baro river to serve as reference for the Government about the potential of owned excavated materials. Study about the potential of excavated minerals in Baro river is done in the form of research such as surface geological mapping, geoelectric survey, test pit, measurements of potential spacious and volume, as well as economic analysis. From the above researches, the informations obtained are about the potential area of the minerals, the quality of sand – gravel materials through the laboratory test, and the economical feasibility.In the research location, there are found excavated materials in the form of sand – gravel with the potential area and volume that can be mined appropriated with the government regulation is about 2.997.319,15 m2. The volume of excavated materials is about 14.986.595 m3 with the depth of 5 meters. The result of laboratory test, the grain size is dominated by gravel and sand with the percentage of gravel is about 28,41% up to 66.53%, the percentage of sand is about 33.21% to 71,44%, and the percentage of silt and clay about 0.10% to 0.48%. According to loss angeles abrassion test, the maximum value is 43.70% and minimum value is 38,53%. As well as the results of soundness test, the maximum value is 0,239%, making the aggregate is very resistant to weathering process. In the economical analysis, the result of the NPV >0, BCR > 1, and IRR > MARR with the value about 7.5%, so that mean the location is recommended for mined economically.