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Abstrak :
Kalimantan Tengah merupakan salah satu daerah dengan potensi cadangan pasir silika terbesar di Indonesia. Pasir silika merupakan mineral bukan logam yang dimanfaatkan sebagai material bangunan. Oleh karena itu, potensi persebaran pasir silika di bawah permukaan diidentifikasi menggunakan survei geofisika. Dalam penelitian ini, metode Resistivitas dengan konfigurasi Wenner Alpha dan Ground Penetrating Radar dengan konfigurasi radar reflection profiling merupakan salah dua metode geofisika yang digunakan untuk mengetahui keadaan bawah permukaan. Metode Ground Penetrating Radar digunakan untuk mengkonfirmasi hasil pengolahan data metode resistivitas karena metode resistivitas dilakukan pengukuran di area dengan permukaan pasir silika sehingga menyulitkan injeksi arus ke bawah permukaan. Selain itu, data bor digunakan sebagai data sekunder untuk membantu dalam interpretasi hasil pengolahan data. Hasil pengolahan data adalah penampang 2D metode Resisitivitas yang berisi nilai resistivitas sebenarnya bawah permukaan dan penampang 2D radargram GPR, serta penampang 2D nilai permitivitas relatif GPR. Berdasarkan hasil tersebut, nilai resistivitas pasir silika sebesar > 136 Ωm dan nilai permivitas relatif sebesar 16 - 26. Dari hasil pengolahan dan interpretasi kedua metode, ditemukan persebaran pasir silika pada kedalaman kurang dari 10 m dan lebih dari 30 m. ......Central Kalimantan is one of the areas with the largest potential reserves of silica sand in Indonesia. Silica sand is a non-metallic mineral that is used as a building material. Therefore, the potential distribution of silica sand below the surface can be identified using geophysical surveys. In this research, the Resistivity method with a Wenner Alpha configuration and Ground Penetrating Radar with a reflection profiling radar configuration are two geophysical methods used to determine the condition of the subsurface. The Ground Penetrating Radar method was used to confirm the results of the resistivity method data processing because the resistivity method was measured in an area with a silica sand surface, making it difficult to inject current into the subsurface. In addition, drill data is used as secondary data to assist in the interpretation of data processing results. The result of data processing is a 2D cross section of the Resisitivity method which contains the actual resistivity value of the subsurface, 2D cross section of the GPR radargram, and 2D cross section of the GPR relative permittivity value. Based on these results, the resistivity value of silica sand is > 136 Ωm and the relative permittivity value is 16 - 26. From the results of processing and interpretation of the two methods, it was found that the distribution of silica sand was at depths of less than 10 m and more than 30 m.

Abstrak :
Silica sand slurry is a multiphase flow that consists of liquid and particle solids. Slurry flow characteristics are affected by particle size, particle distribution, particle concentrate, pipe geometry, flow regime, and viscosity factors. Spiral pipe is one of the solutions to increase drag reduction at a certain velocity and Reynolds number (Re). The aim of this experiment is to figure out the influence of using spiral pipe in increasing drag reduction of silica sand slurry flow. The pipeline used is spiral pipe with a helicial tape with two ratios of pitch per diameter (p/D), i.e. = 4 and 7. The test loop is set up as 3,500 mm (3.5 meters) in length. The size of the particle is 1 mm in diameter. The mean density of the silica sand particles is 2,300 kg/m3. The velocities are set between 1m/second and 5m/second. The percentage of volumetric concentration of solids in slurry (Cw) varies between 20%, 30%, and 50% in weight. Particle concentration, the Reynolds number and ratio of pitch and diameter give significant impact to the drag reduction. At a ratio of pitch/diameter (p/Di) = 7, at a Reynolds number (Re) of 30,000 and at Cw 50% can increase drag reduction to about 33%.