Pengaruh Pelapukan Batulempung Formasi Subang terhadap beberapa Sifat Keteknikannya Guna Menunjang Efektivitas Pemilihan Desain Perkuatan Lereng

Dalam makalah ini dibahas karakteristik pelapukan batulempung Formasi Subang dalam kaitannya dengan sistem klasifikasi derajat pelapukan batuan dan perubahan nilai beberapa sifat keteknikannya. Lokasi pengamatan lapangan dan pengambilan contoh batuan dilaksanakan di daerah Karawang Selatan, Jawa Barat, karena kehadiran jenis batuan ini menempati wilayah yang cukup luas. Secara umum batulempung Formasi Subang dapat dibedakan atas enam zona yang mencerminkan perbedaan derajat pelapukannya. Hasil pengujian beberapa sifat keteknikan yang merupakan parameter dasar dalam analisis kestabilan lereng, seperti berat isi, kohesi, dan sudut geser dalam, memperlihatkan adanya hubungan yang berarti terhadap perubahan derajat pelapukannya. Maka, dengan mengetahui variasi derajat pelapukan batulempung Formasi Subang diharapkan perencanaan atau pemilihan desain (jenis) perkuatan lereng dapat dilakukan secara lebih tepat dan eifisien.Influence of Weathering in Claystone of Subang Formation on Some Engineering Properties to Effectively Support in Choosing of Slope- Reinforcement DesignThis paper presents weathering characteristics of claystone of Subang Formation in relation to weathering grade classification system and changes of some engineering properties. The field observation and rock-soil sampling were located at Southern Karawang area, West Java, where the claystone is distributed widely. Generally, claystone of Subang Formation can be classified into six degrees of weathering. The examination results of some engineering properties, such as unit weight, cohesion, and internal friction angle as basic parameters of slope stability analysis, indicate good relationship with the change of weathering grade. As an implication, by knowing various weathering grades, the planning or choosing of slope-reinforcement-design will be more effective and efficient.

Studi Geologi Teknik Tapak Penyimpanan Akhir Limbah Radioaktif (LRA) Demo Plant Tipe NSD Kedalaman Menengah Di Puspiptek, Serpong

Penyimpanan akhir limbah radioaktif bertujuan untuk menjaga agar zat radioaktif tidak terlepas ke lingkungan sampai aktivitas zat tersebut turun ke level yang aman. Konsep penyimpanan akhir limbah radioaktif (LRA) yang akan dikembangkan di area Pusat Penelitian Ilmu Pengetahuan dan Teknologi (Puspiptek), Serpong adalah penyimpanan akhir limbah radioaktif dekat permukaan (near surface disposal - NSD). NSD berdasarkan kedalaman terbagi dua macam yaitu NSD dekat permukaan dan NSD kedalaman menengah. Konsep NSD pada penelitian ini adalah NSD kedalaman menengah, yaitu antara 30–300 meter. Pada saat konstruksi NSD di kedalaman menengah dibutuhkan pekerjaan ekskavasi bawah permukaan atau pembuatan terowongan. Analisis tegangan in-situ dan deformasi bawah permukaan dilakukan untuk mengetahui besaran dan distribusi tegangan yang terbentuk di dalam tanah/batuan serta deformasi yang terjadi pada saat dilakukan ekskavasi bawah permukaan. Berdasarkan analisis diketahui nilai tegangan dan sebaran tegangan tensional maupun kompresional berkisar antara -441 kPa sampai 4,028 kPa dengan nilai deformasi alami atau tanpa perkuatan antara 4,4 cm sampai 13,5 cm. Nilai deformasi yang cukup besar dimana mencapai 13,5 cm menunjukkan diperlukan rekayasa perkuatan pada saat ekskavasi. Desain rekayasa perkuatan pada setiap tahapan ekskavasi mengacu hasil pemodelan pola distribusi tegangan dan deformasi. Final disposal of radioactive waste intended to keep radioactive substances does not released to the environment until the substance activity decreased to the safe level. Storage concept of radioactive waste (RAW) final disposal that will be developed at the area of Puspiptek, Serpong is near surface disposal (NSD). Based on depth, NSD divided on two type, near surface NSD and medium depth NSD. Concept NSD in this research is medium depth NSD, which is between 30–300 meters. During NSD construction in medium-depth required the works of sub-surface excavation or tunneling. Analysis of in-situ stresses and sub-surface deformation performed to recognize the stress magnitude and its distribution that developed in soil/rock as well as the deformation occurred when sub-surface excavation takes place. Based on the analysis, acknowledged the magnitude of tensional and compression stress and its distribution that range from -441 kPa to 4.028 kPa with values of natural deformation or without reinforcement between 4.4 to 13.5 cm. A rather high deformation value which is achieved 13.5 cm leads to necessity of engineering reinforcement during excavation. The designs of engineering reinforcement on every excavation stage refer to the result of modeling analysis of stress and deformation distribution pattern

Kajian Ketahanan Batuan Clay Shale Formasi Jatiluhur di Sentul City Jawa Barat

The mechanical properties of Clay Shale are very unique. When it is dry, it shrinks and hardens, butwhen it absorbs water, it swells and to some extent loses its shear strength so that the drop-instrength can occur suddenly even with its own weight. Due to the nature of the swell-shrink that arestrongly influenced by climate and weather, clay shale durability may decrease over time when indirect contact with air and water. Research on clay shale was done in Sentul City, Bogor - West Java,Indonesia on Jatiluhur formation, using dynamic slaking (slake durability test) and slaking static test.Dynamic slacking test is done in three times i.e. after sampling, after 3 months and after 9 months.Slake durability test results from 3 different drilling points, shows that within 9 months, has not seenthe decreasing effect of durability. With a low Plasticity index, the durability research in Sentul City isin medium durability to medium-high durability classification

The Effect of Highway Vibration to The Hills Slope Stability by an Integrated GPS-Vibration Data Processing

Bandung-Jakarta, Indonesia highway have high density vehicles pass even often jammed. High activity of vehicles cause repeated vibrations and occur continuously. In case, the highway that divides the hills. The passing vehicles give rise repeatedly vibration and indicated disturbance of hillside slope stability. Vehicles vibration depend on speed, weight, number of vehicles and road construction materials. A method in question is counting a vehicle volume and determine the volume pattern of the vehicle. The magnitude of vibration is function of the object distance from the sources. The magnitude of the vibration effect is very dependent on the geological structure of hills formation. Hilly slope stability indicates experiencing interference if the object or material slope changes position or displacement. GPS observation give position changes and its displacement. The effect of Toll road vibration to slope stability is known by GPS and Vibration simultaneous measurement. Data acquisition used six unit GPS receivers and six unit vibration sensor which is installed on the hillside beside the highway. Integrated data processing techniques using Empirical Mode Decomposition (EMD). Integrated GPS-Vibration data are implemented to find actual displacement which are caused by highway vibration

Landslides induced by slaking of geomaterial

The geological event that happens because of an unbalance between shear strength and shear stress on rock mass is known as a landslide. This usually occurs due to improper handling of the exposed material. The landslide occurs because of the reaction to reduce the burden it bears so that the mass of the rock will move rock mass from the higher elevation to lower elevation. Many landslides, in west java, Indonesia occurred on exposed clay shale that is protected by soldier pile with 3m in distance between pile. On top of the clay shale, there is a building which gives an additional load on the clay shale. To determine the effect of water and temperature on clay shale, static slaking index test was conducted. With a submerge variation, it was found that the slaking index value ranged from 2.17% to 12.0% with the slaking classification from very low to medium. The size distribution was produced from 1/4 and 1/2 sample submerge show bigger rock breakage than rock with 3/4 sample submerge and sample fully submerge. Observations of the sample in room temperature without contact of water and no additional mass were also done. The sample was still intact until the end of research work

Landslides induced by slaking of geomaterial

The geological event that happens because of an unbalance between shear strength and shear stress on rock mass is known as a landslide. This usually occurs due to improper handling of the exposed material. The landslide occurs because of the reaction to reduce the burden it bears so that the mass of the rock will move rock mass from the higher elevation to lower elevation. Many landslides, in west java, Indonesia occurred on exposed clay shale that is protected by soldier pile with 3m in distance between pile. On top of the clay shale, there is a building which gives an additional load on the clay shale. To determine the effect of water and temperature on clay shale, static slaking index test was conducted. With a submerge variation, it was found that the slaking index value ranged from 2.17% to 12.0% with the slaking classification from very low to medium. The size distribution was produced from 1/4 and 1/2 sample submerge show bigger rock breakage than rock with 3/4 sample submerge and sample fully submerge. Observations of the sample in room temperature without contact of water and no additional mass were also done. The sample was still intact until the end of research work

ANALISIS KESTABILAN DAN PERKUATAN LERENG MASSA BATUAN MENGGUNAKAN SLOPE MASS RATING DAN ROCK MASS RATING DI JALAN RAYA TAWAELI – TOBOLI KM 52 – 64, PALU, SULAWESI TENGAH

Pembangunan infrastuktur yang pesat di dunia, khususnya di Indonesia, mendorong berbagai sektor terkait untuk mengembangkan pengetahuan dan teknologi.Geologi Teknik sebagai salah satu bidang yang memegang peran penting dalam pembangunan infrastruktur perlu mendapat perhatian khusus. Salah satu metode Geologi Teknik dalam observasi awal untuk menentukan status keamanan pembangunan adalah klasifikasi massa batuan. Klasifikasi massa batuan memberikan pendekatan kuantitatif dalam penentuan karakteristik massa batuan. Jalan Raya Tawaeli – Toboli km 54 – 62, Palu, Sulawesi Tengah merupakan jalan raya nasional yang berasosiasi dengan banyak lereng. Lereng di titik SC-08 pada daerah penelitian memiliki nilai Slope Mass Rating (SMR) 7 yang termasuk dalam kelas V (lereng sangat tidak stabil). Untuk mencegah keruntuhan pada lereng tersebut, SMR memberikan rekomendasi perkuatan golongan Va berupa pemasangan gravity / anchored wall atau ekskavasi ulang. Lereng di titik SC-08 pada daerah penelitian memiliki nilai Rock Mass Rating (RMR) 58 yang termasuk dalam kategori batuan sedang (fair rock). Berdasarkan fracture spacing dan point load index, metode ekskavasi yang tepat untuk lereng di titik SC-08 adalah digging excavation (penggalian). RMR memberikan beberapa parameter desain dan sifat keteknikan pada lereng ini, antara lain nilai kohesi sebesar 0.2 - 0.3 MPa, sudut geser dalam sebesar 25˚ - 35˚, sudut aman pemotongan lereng kurang dari 55˚, dan allowable bearing pressure sebesar 280 – 135 T/m2. Kata kunci :Slope Mass Rating, Rock Mass Rating, tipe perkuatan,metode ekskavas

A physical study of the effect of groundwater salinity on the compressibility of the Semarang-Demak aquitard, Java Island

This article is currently under review oin Journal of Geosciences, MDPI. Authors: Dwi Sarah, Lambok Hutasoit, Robert Delinom, Imam A. Sadisun, Taufiq Wirabuana -- Semarang-Demak and other cities along the coast of North Java are vulnerable to land subsidence. The presence of saline groundwater in the coastal region is thought to affect the high subsidence rate, in this case the compressibility of the aquitard layer. We aimed to analyze the effects of groundwater salinity on the compression characteristics of the Semarang-Demak clay using physical analysis. Methods included the determination of groundwater salinity, clay mineralogy and fabrics, and consolidation tests under various salinity conditions. The Semarang-Demak clay is dominated by smectite of high activity and saline clay exists at the depth of 10 to 35 m. Consolidation tests reveals that the increase of salinity increases the average consolidation rate and hydraulic conductivity up to 42% and 37.5%, respectively. Clay fabric analysis showed that the groundwater salinity modified the interconnectivity of pores by changing the fabric into parallel alignments, facilitating faster porewater dissipation, hence the clay is more readily compressed. These findings are useful for explaining the mechanism of the fast-subsiding coastal plains of North Java

Polygon-based Landslide Inventory for Bandung Basin Using Google Earth

A landslide inventory representing landslide locations is used as a key factor in landslide susceptibility assessment. This paper explores Google Earth (GE) for generating a polygon-based landslide inventory in Bandung Basin. How far GE can identify landslides and their boundaries, source areas, and types were discussed here. Visual interpretation of GE images supported by path tool in GE, official landslide reports, previous research papers, and media was performed. The result is a polygon-based landslide inventory consisting of 194 landslide areas and 194 landslide source areas during 1993-2020. The limitations of GE in preparing the landslide inventory are (1) not covering the timing of the landslide occurrences, (2) tricky to identify small landslides (<100 m2) in anthropogenically transformed areas, and (3) not able to distinguish between earth and debris of landslide material