Groundwater Exploration in Tirtoadi using the Geoelectric Schlumberger Method

Tirtoadi sub-district is one of the areas mentioned as being on alert for meteorological drought, which is a condition of not experiencing a day without rain (HTH) for more than 60 days. This research aims to provide information on the presence of subsurface water using geoelectric methods. Data acquisition was carried out at 20 points in Tirtoadi. The distribution of points is random but evenly distributed in the research area. The equipment used is Syscal Jr and the measuring range is 600 m AB, and the direction of the stretch is relatively north to south. The field data obtained are deltas V and I. These data are used to calculate R and Rho. The resistivity value obtained is the apparent resistivity. To obtain a subsurface model of the actual resistivity, it is necessary to perform a 1-D inversion. The inversion is carried out using the Progress V3.0 software. The results obtained in this study are variations in the value of subsurface resistivity. Resistivity of water-containing aquifers ranges between 10 ?m – 50 ?m. The depth of groundwater varies between 50 meters to 80 meters. The thickness of the groundwater varies between 5 meters to 22 meters. The recommended drill point is given at T11 with coordinates 49 S 424996 N 9144372 E because at this point it has the shallowest depth and thick enough thickness.

Thermo-Mechanical and Delamination Properties in Drilling GFRP Composites by Various Drill Angles

This manuscript aims to study the effects of drilling factors on the thermal-mechanical properties and delamination experimentally during the drilling of glass fiber reinforced polymer (GFRP). Drilling studies were carried out using a CNC machine under dry cutting conditions by 6 mm diameter with different point angles of ∅ = 100°, 118°, and 140°. The drill spindle speed (400, 800, 1600 rpm), feed (0.025, 0.05, 0.1, 0.2 mm/r), and sample thickness (2.6, 5.3, and 7.7 mm) are considered in the analysis. Heat affected zone (HAZ) generated by drilling was measured using a thermal infrared camera and two K-thermocouples installed in the internal coolant holes of the drill. Therefore, two setups were used; the first is with a rotating drill and fixed specimen holder, and the second is with a rotating holder and fixed drill bit. To measure thrust force/torque through drilling, the Kistler dynamometer model 9272 was utilized. Pull-in and push-out delamination were evaluated based on the image analyzed by an AutoCAD technique. The regression models and multivariable regression analysis were developed to find relations between the drilling factors and responses. The results illustrate the significant relations between drilling factors and drilling responses such as thrust force, delamination, and heat affect zone. It was observed that the thrust force is more inspired by feed; however, the speed effect is more trivial and marginal on the thrust force. All machining parameters have a significant effect on the measured temperature, and the largest contribution is of the laminate thickness (33.14%), followed by speed and feed (29.00% and 15.10%, respectively), ended by the lowest contribution of the drill point angle (11.85%).

PENENTUAN LOKASI TITIK BOR AIR TANAH BERDASARKAN METODE TAHANAN JENIS 2D DI DESA SUBUR MAKMUR KABUPATEN KOTABARU, KALIMANTAN SELATAN

Subur Makmur Village is an area where the availability of clean water is difficult, especially during the dry season. One of the sources of water that can be used by the villagers is groundwater. However, to obtain groundwater, it is necessary to drill wells and investigate the aquifer layer first. This study aims to obtain an overview of the subsurface layers based on the resistivity properties of the rock, so that the aquifer layer can be identified and can determine the exact location of the drill point in the prospective aquifer position that may be encountered. The geoelectric method is the most efficient method for detecting aquifer layers. It uses two types of configurations, namely, the Wenner and Wenner-Schlumberger configurations where the number of geoelectric paths is one path. The length of the track used is 540 meters, the number of electrodes is 28 with the spacing between the electrodes is 20 meters. The resistivity cross section for both configurations, obtained resistivity values of 11 - 140 Ohm meters. Composed of 2 (two) rock units, namely graywacke sandstone rock units. Consists of graywacke sandstones with claystone inserts. Density value ≥ 40 Ohm meter. Hydraulic properties, small porosity, small permeability, the potential for groundwater in this unit is small. The position of this unit is at a depth of 40 m. In the cross section, the resistivity is yellow - red. The second rock unit comprising this trajectory is the alteration claystone unit consisting of claystone containing bolders of sandstone / igneous rock. Resistivity value ≤ 40 Ohm meter. The position of this unit is on the Surface to a depth of 40 m. Hydraulic properties, large porosity with very small permeability, the potential for groundwater is very small. In the cross section of this unit resistivity are colored dark blue, blue and green. From the resistivity cross section, it can be determined the position of the borehole which is effectively located in the length range of the trajectory between 360 - 420 meters. Keywords: subur makmur, groundwater, wenner, wenner-schlumberger

DRILL BIT SELECTION USING DESIGN OF EXPERIMENTS (DoE) METHOD

Drilling process is one of the most common machning process in industrial sector. More than half of the metal-cutting processes are conducted by the drilling process. Drill bit has influenced the results of the drilling process. Therefore, selection of the suitable drill bit becomes a critical factor in the drilling process. This is because the use of the suitable drill bit could fulfill the determined specification value of the hole. Six Sigma and Failure Mode Effect Analysis (FMEA) methods are used to identify factors that have influenced the results of the drilling process. Then by using the Design of Experiment, selection of the best drill bit could be done. In this study, 2 factors that influenced the result are the drill bit type and the drill point angle. Significance test using nested design through MINITAB 14 application has shown that both factors have significant influence over the hole diameter size.. Then by using the plot from the MINITAB 14 application, HPMT 1 became the best drill bit because it could fulfill the specification value. As for the best point angle in this study is 139.72º. Process capability calculation of HPMT 1 has shown that the process is in control. The conclusion is that drill bit HPMT 1 with point angle 139.72º became the best option in this study.

PROSES ANALISA DINDING GALIAN BASEMENT 7 LANTAI DENGAN METODE ELEMEN HINGGA

Limited area for construction can be overcome by build a multi-story building with basement. Basement is quite common in Jakarta, the things that attracted is basement with 7 stories. This basement construction use a diaphragm wall with 1 meter thickness for the retaining wall and installation strut every 4 meter. Deformation for diaphragm wall is calculated by finite element method application and mohr-coloumb soil modeling. This calculation based on soil type from each drill point and water table when it high or common. From the calculation, maximum deformation diaphragm wall for BH-5 when water table high is 235,86 mm and when water table at -3 m is 209,6 mm. Maximum deformation diaphragm wall for BH-7 when water table high is213,9 mm and when water table at -3 m is 197,18 mm. There are several things that need to concern when constructed basement and deep excavation, in case to avoid failure.AbstrakKeterbatasan lahan untuk pembangunan dapat diatasi dengan pembangunan gedung bertingkat yang dilengkapi dengan basement. Pembangunan basement cukup umum di Jakarta ini, salah satu hal yang menarik perhatian adalah pembangunan basement sebanyak 7 lantai. Pembangunan basement ini menggunakan dinding penahan tanah berupa dinding diafragma dengan ketebalan 1 meter dan pemasangan strut setiap 4 meter. Perhitungan deformasi pada dinding penahan tanah ini dilakukan dengan menggunakan aplikasi metode elemen hingga dan permodelan tanah mohr-coloumb Permodelan dilakukan berdasarkan keadaan tanah pada tiap titik bor dan keadaan muka air saat banjir atau kemarau. Dari perhitungan, didapatkan deformasi maksimum dinding diafragma pada titik bor BH-5 pada muka air banjir adalah 235,86 mm dan pada muka air kemarau adalah 209,6 mm. Untuk deformasi maksimum dinding diafragma pada titik bor BH-7 pada muka air banjir adalah 213,9 mm dan pada muka air kemarau adalah 197,18 mm. Pada saat konstruksi basement dan galian dalam, diperlukan beberapa hal yang perlu diperhatikan agar tidak terjadi kegagalan pada saat pembangunan dan penggunaan basement.

Monitoring of hole surface integrity in drilling of bi-directional woven carbon fiber reinforced plastic composites

Fiber-reinforced plastic is one of the top priorities lightweight materials with excellent mechanical properties for the aerospace industries in recent years. However, it is difficult to machine despite having unique properties due to its non-homogeneous and abrasive nature in alternate fiber and matrix layers. Thus, it is found to be a challenging task to drill hole on such hard-to-machine materials, which is highly essential for the development of most of the engineering structural components. The present work addresses various drilling-induced defects such as delamination, circularity error, and roughness variations in the hole surface during drilling of quasi-isotropic cross-fiber oriented bi-directional woven-type carbon fiber reinforced plastic laminate using a full factorial design of experiments for different drill geometry. The response surface methodology was considered for the regression model development, which was found to be highly significant. The machining forces with associated torque have also been acquired during drilling, which was divided and further analyzed in time domain to correlate with drilling flaws. The drilling-induced delamination was found to be higher at a high feed rate using a higher drill point angle due to substantial thrust force generation at the initial stages in the drilling cycle. However, the internal surface finish with associated circularity error was reduced for higher spindle speed with less feed rate using a low drill point angle because of low torque fluctuation at the final drilling phases. The axial thrust force was found to be a prime indicator of drilled hole surface delamination, whereas drilling torque precisely indicated internal surface roughness as well as circularity error. The global root mean square, along with a local peak of thrust and torque, both were highly essential to completely characterize the drilled hole quality.