Studi Potensi Bahan Galian Bijih Emas (Au) Menggunakan Data Geolistrik Pada Desa Buang Baru Kecamatan Sekatak Kabupaten Bulungan Kalimantan Utara

Studi potensi bahan galian emas (Au) dilakukan di Desa Buang Baru, Kecamatan Sekatak, Kabupaten Bulungan, Kalimantan Utara dengan menggunakan data geolistrik konfigurasi Pol - Dipol sebanyak 4 titik. Metode geolistrik merupakan salah satu metode geofisika yang digunakan untuk mengetahui kondisi geologi bawah permukaan berdasarkan sifat kelistrikan batuannya. Emas merupakan native element dari batuan beku yang mempunyai sifat kelistrikan batuan yang kontras dengan batuan disekitarnya yang umumnya berupa batuan sedimen, sehingga metode geolistrik cocok digunakan untuk mengidentifikasi keberadaannya di bawah permukaan sekaligus menghitung potensi  volume. Kegiatan pengukuran menghasilkan dua macam model, yaitu penampang 2D dan block model 3D. Pesebaran nilai tersebut diinterpretasikan sebagai lokasi keberadaan dari potensi emas yang terdapat diarea pengukuran. Area dengan nilai resistivity >1000 ohm.m diinterpretasikan sebagai area pesebaran batuan tersilisifikasi. Area dengan nilai 100-1000 ohm.m diinterpretasikan sebagai area pesebaran batuan terargilitkan dengan didalam area-area tersebut, terdapat interpretasi dari keberadaan bijih emas, yaitu area berwarna ungu kemerahan dengan nilai IP >250 msec. Interpretasi model 3D menunjukan bahwa alterasi batuan di area pengukuran secara umum didominasi oleh batuan yang terargilitkan. Batuan tersilisifikasi secara umum mengisi bagian tepi dari batuan terargilitkan pada model dengan bijih terbentuk diselimuti oleh batuan-batuan tersebut. batuan yang diinterpretasikan mengandung emas, terhitung memiliki volume 623.000 m3

Physical Model of Vertical Water Movement Inside a Soil-Column Apparatus for Infiltration Study with A Two-Way Orientation Approach

To improve the theory of Richard's equation, studying infiltration under free-draining conditions at the ground surface is necessary. Verification is required to clarify the physical model of water movement. The aim of this study was to describe multistage measurements of both the wetting and the drying front scheme of one-dimensional infiltration at laboratory scale. A soil-column infiltration apparatus was built consisting of a double acrylic wall, a sensor set and a light bulb. Acrylic was chosen as the material for the wall to minimize possible heat conduction on the wall side, which was wrapped in double insulation to achieve adiabatic condition. The following three main sensors were used and controlled by a microcontroller: water-content, pressure and temperature sensors. Meanwhile, the light bulb at the top of the apparatus was set to non-isothermal condition. The instrument was successfully built to describe vertical water movement. Slight modifications were carried out to ensure more precise observation. This resulted in the initiating of new shape interpretation based on the water-ponding measurement to refine the simplified pattern that was introduced by the conventional Green-Ampt theory

Correlation between Compressive Strength of Concrete and Flexural Strength of Concrete Using Local Aggregates

Compressive strength and flexural strength are two important parameters in the concrete job mix formula. Both parameters are strongly influenced by the characteristics of the constituent aggregates. This study aims to obtain the relationship between the compressive strength and flexural strength of concrete mixtures using local aggregates for construction projects around the province of South Kalimantan. The experimental mechanism was carried out by examining aggregates and designing concrete proportions using type V Portland cement with an initial setting time of 80 minutes and a final setting time of 150 minutes. Meanwhile, coarse aggregate from Katunun and fine aggregate from Barito are used in the concrete job mix formula. In this case, the results of the analysis show that there is a correlation value (K) for f'c 30 MPa and f'c 35 MPa, which are 0.84 and 0.78, respectively

EVALUASI PEMODELAN BANJIR 2-D KOTA MANADO

Permasalahan banjir Kota Manado merupakan permasalahan utama yang wajib ditangani secara komprehensif. Perubahan tata guna lahan, intensitas curah hujan yang sering dan lama, kapasitas tampung sungai yang mengecil, sedimentasi dan sampah, dan perubahan iklim menjadi penyebab terjadinya banjir di Kota Manado. Penelitian ini menggunakan pendekatan model dua dimensi dengan simulasi efek perubahan tata guna lahan dan efek hujan kala ulang serta observasi banjir guna mencari solusi terhadap permasalahan banjir yang sering terjadi di Kota Manado. Hasil dari penelitian ini adalah terjadi perubahan tata guna lahan dan peningkatan luas area terdampak banjir yang menggenangi Kota Manado, di lain hal kapasitas sungai yang kecil, sehingga pemerintah Kota Manado perlu memperbaiki daerah sempadan sungai yang dipadati dan dihuni oleh masyarakat guna meningkatkan kapasitas aliran air di sungai saat musim hujan dengan intensitas lama dan besa

Pengaruh Kurva Histeresis Terhadap Model Stabilitas Lereng Timbunan Akibat Kegiatan Pertambangan Di Zona Lahan Basah

Landfill of residual soil due to mining activity in the wetland area is a relatively complex issue due to the soft soil conditions that are vulnerable to landslides. The stabilization method to increase the safety factor from landslide hazard can be done by decreasing the degree of water saturation in the soil disposal. In this case, the dominant mechanical parameters used in slope stability analysis will be elaborated with the SWCC concept for soft soil. While the conceptual model is built, it is based on the phenomenon of negative pore water pressure that appears in the vadose zone on the groundwater surface. The information provided from the hysteresis curve configuration can be used as an additional reference for the optimistic disaster analysi

Physical Model of Vertical Water Movement Inside a Soil-Column Apparatus for Infiltration Study with A Two-Way Orientation Approach

To improve the theory of Richard's equation, studying infiltration under free-draining conditions at the ground surface is necessary. Verification is required to clarify the physical model of water movement. The aim of this study was to describe multistage measurements of both the wetting and the drying front scheme of one-dimensional infiltration at laboratory scale. A soil-column infiltration apparatus was built consisting of a double acrylic wall, a sensor set and a light bulb. Acrylic was chosen as the material for the wall to minimize possible heat conduction on the wall side, which was wrapped in double insulation to achieve adiabatic condition. The following three main sensors were used and controlled by a microcontroller: water-content, pressure and temperature sensors. Meanwhile, the light bulb at the top of the apparatus was set to non-isothermal condition. The instrument was successfully built to describe vertical water movement. Slight modifications were carried out to ensure more precise observation. This resulted in the initiating of new shape interpretation based on the water-ponding measurement to refine the simplified pattern that was introduced by the conventional Green-Ampt theory