Resistivity Laboratory Measurement of Geomaterial

Resistivity Laboratory Measurement of Geomaterial


 
Haryati Awang

Institute for Infrastructure Engineering and Sustainable Management, Faculty of Civil Engineering, Universiti Teknologi MARA, 40450 Selangor, Malaysia e-mail: harya406@salam.uitm.edu.my

Cho Gye-Chun
Professor
Department of Civil and Environmental Engineering, KAIST, Daejon, Korea
e-mail: gyechun@kaist.ac.kr 




ABSTRACT 

      Electrical electrical resistance is sometimes measured as field survey because it is one in every of geology ways that's presently utilized in web site investigation program for subterranean identification. issues in quantifying the electrical resistance worth of geomaterial may well contribute to a hollow knowledge assortment for geotechnical assessment. As consequences this method is a smaller amount appreciated by engineers because it could also be sophisticated in acceptive the interpretation of the electrical resistance profile of the subterranean. This paper presents finding on experimental study in developing electrical electrical resistance mensuration of geomaterial together with soil and rock. the aim of this laboratory study is to determine a laboratory take a look at technique of electrical electrical resistance mensuration exploitation resistance meter or a LCR meter, therefore then electrical resistance index of geomaterial is created. attributable to the objectives of this study, a configuration take a look at was distributed on a bunch of artificial and real rock samples to get a perfect frequency for the geo-material. The tests were performed by connecting the cables to the 2 current electrodes at the each ends of the sample. The electrical resistance mensuration on homogenized rock sample (gypsum) at five hundred kc frequency showed a result that the variations in sample thickness don't influence the electrical resistance worth of the fabric. a perfect wet content of fifty six of the geo-material results a continuing electrical resistance worth. As for validation for this laboratory experiment, a field electrical resistance take a look at was distributed to live the particular electrical resistance worth on web site. By comparison field and laboratory results, this technique is applied to soil and rock material for electrical resistance index determination. 

 INTRODUCTION

      Field technique of electrical electrical resistance is currently ordinarily utilized in web site investigation to get the knowledge of the subterranean together with the profiles and therefore the geo-material index. Realizing that the electrical electrical resistance technique within the gift development doesn't offer direct quantitative knowledge on engineering parameters besides the interpretation of the subterranean image need high personnel talent, there's a desire to full fill the void during this issue. moreover, so far there's no important electrical electrical resistance index for geo-material particularly for tropically worn rock and so it's positively laborious to interpret the electrical electrical resistance result from this region. this application on electrical electrical resistance is a smaller amount appreciated by technical personnel significantly civil engineers with the rationale that the info provided, is hollow to engineering work. Thus, the technique is a smaller amount considerable to be used in engineering science works. For these reasons this analysis was distributed to develop a non-destructive take a look at in laboratory exploitation electrical electrical resistance thought that is termed as geo-resistivity technique. 

     The geo-resistivity could be a technique wherever current is applied to the bottom samples and totally different in its potential produces geo-resistivity values. This study was distributed as Associate in Nursing improvement study of electrical electrical resistance  technique that's popularly utilized in field mensuration. 

MATERIALS And METHODS

Materials

      Two varieties of material, mineral (artificial rock) and arenaceous rock (real rock) were utilized in this study as shown in Fig. 1. For the aim of frequency configuration, artificial rocks were ready exploitation mineral powder and water. The mineral powder of 1000g mixed with 650 cc of water in PVC tube to make sculptural cylindrical form kind of like cored sample of rock with dimension of fifty metric linear unit diameter. For real rock samples variety of arenaceous rock were collected from a web site at Puncak Alam and Bukit Kerayong of Selangor state, Malaysia. Some blasting and excavation activities from the sites offer samples for laboratory analysis for many weathering grades. to get cylindrical form samples, the blocks were cored to NX core size. each mineral and sandstones were ready in fifty metric linear unit diameter (D) cored samples and therefore the thicknesses or length (H) ranging from 20 mm to 115 mm.

Experimental Set-up

      An important equipment of electrical electrical resistance mensuration device within the laboratory, a resistance meter, LCR meter model LCR-821, with frequency vary from twelve cycle to one thousand kc was utilized in this study as shown in Fig. 2. The LCR meter was functioning as electrical resistance instrument to live the resistance of a fabric once current is applied between each ends of the fabric. Power offer for the LCR meter was sourced from AC current of 240 V. This meter was connected with two wires (provided) of radial and axial leaded parts. The sizes of the sample depend upon the target of the damaging take a look at once the electrical resistance take a look at. different equipment is sample holder that fictional with rotation gear and clamping devices. The clamping pressure is constant by the cell pressure that was put in at one finish of the holder. Electrical electrical resistance mensuration were performed with 2 wires from four terminals (connected to check fixtures) were connected to the 2 current electrodes. To measure the resistance of the sample, the LCR meter was turned to R/C mode. By connecting the 2 ends of the cables to 2 current electrodes at the each ends of the sample, resistances reading were recorded.

Instrument Self-Calibration

      Calibration on the resistance meter (LCR) was distributed before conducting resistance mensuration on the sample because it is vital a part of the take a look at technique. the aim of standardisation is to urge the correct and consistence reading of the tested material. In actual electrical resistance mensuration, Associate in Nursing extension of the mensuration port with cables or take a look at fixture was connected. For standardisation purpose open and short zeroing method should be done as in Fig. 3. Zeroing is one in every of the self-calibrations before running the take a look at. so as to eliminate strayed electrical resistance of take a look at cable and take a look at fixtures throughout the mensuration, the four (4) take a look at cables/ fixture error should be corrected before any mensuration is distributed. The corrections ar calculated and hold on in memory of the LCR Meters throughout the zeroing method. once passing the zeroing method, (if the zeroing method is palmy, a message of ‘OK’ can seem in LCR meter. If failing a message of “ FAIL” can appear) the mensuration can show ‘zero’ (~0) once tested on ‘short test’.

Frequency Configuration Test

       To measure the resistance of a solid or liquid material, it needs configuring the frequency as a result of each material has it own frequency. the aim of frequency configuration is to pick out the perfect frequency of rock material for resistance mensuration. a continuing resistance reading are going to be created at a particular frequency vary that is termed as frequency configuration. Associate in Nursing electrical resistance mensuration of a fabric {in a|during a|in Associate in Nursing exceedingly|in a very} circuit of Associate in Nursing AC at a given frequency is outlined by an 

impedance vector consists of a true half (resistance, R) Associate in Nursingd an pure imaginary number (reactance, X) or in polar type as a magnitude, |Z| and phase, θ and mathematically it is expressed as 

      The cable and text fixture should be zeroed at every time the frequency and material is modified. to make sure the accuracy of the cable and take a look at fixtures, mensuration was created by connecting each cables. Results of R = -0.0008 ohm (nearly zero) was shown. For frequency configuration, shaped mineral was wont to simulate the homogenized rock. The solid sample was tested for resistance mensuration and readings were recorded exploitation LCR meter.

RESULT AND DISCUSSIONS

Frequency Configuration 

      Graph in Figure three shows the frequency configuration of the solid mineral representing ground material. The resistance shows a stable response at the frequency between one hundred kc to one thousand kc as shown in Figure 3(a). The vary of import is suited to the high resistance material like rock. letter (θ) achieved nearly zero reading (θ~0) at five hundred kc that mean that the Z = R at that frequency Figure three (b). in the meantime the capacitance mensuration shows constants reading from one hundred kc to one thousand kc Figure 3(c).

      The mensuration for the mineral or land material ought to be performed at the frequency of five hundred kc as a result of at this frequency it offers a perfect resistance, R. This frequency are going to be set for any mensuration for solid material like rock because it showed a continuing reading. This configuration explains that in any material that beneath choose a resistance take a look at exploitation the higher than aforementioned LCR meter at five hundred kc frequency, the result provides a true resistance worth of the material.

Geometric impact

      Results on meter on geo-resistivity as given in Figure four were obtained once the standardisation and configuration of the frequency. results of the electrical resistance mensuration on homogenized rock sample (gypsum) at five hundred kc frequency shows that the variations in sample thickness (H: D) don't influence the electrical resistance worth of the fabric at the wet content of fifty five.96% in average. the quality deviation of zero.96 worth advised that the electrical resistance worth clustered closely round the {mean worth|mean|average|norm} created a linear horizontal line to indicate the constant value that is at three.39.

CONCLUSIONS

      As conclusions the event on the laboratory testing of geo-resistivity is with success started exploitation electrical resistance instrument equipment that supported frequency configuration. By this finding, electrical resistance of core samples is measured at any thickness with regards to the dimension needed by damaging take a look at like H=2D for UCS and H=D for purpose load take a look at. It can also be complete that at Associate in Nursing known frequency, variation in sample thickness doesn't influence the electrical resistance worth of homogenized material as long because the wet content is management at specific vary. Finally, on varied thicknesses of cylindrical rock samples, the geometric changes don't show any impact to geo-resistivity.

REFERENCES

 

1. Antoine, M. M. and J. M. Bradford (1982) “Parameters for Describing Soil Detachment due to Single-Water Impact,” Sad Sam Soc. Am. J., 46, 36-840. 
2. Awang, H., Nawawi, M.N., Mohammed, Z (2006) “A laboratory study on the influence of dc and ac current on electrical resistivity index of geo-materials” National Seminar on Civil Engineering Research. 19-20 December 2006. Johor Bharu. 
3. Muhammad Syukri, Dr. Rosli Saad, Dr. M.M. Nordiana, and I. N. Azwin: “Preliminary Study of Sumatera Fault Using 2-D Resistivity Imaging Method” Electronic Journal of Geotechnical Engineering. 
4. Abdoullah Namdar: “Tsunami and Liquefaction Resistance of Subsoil” Electronic Journal of Geotechnical Engineering, 2013. 
5. Muhammad Syukri, Dr. Rosli Saad, Dr. M.M. Nordiana, and I. N. Azwin: “Preliminary Study of Sumatera Fault Using 2-D Resistivity Imaging Method” Electronic Journal of Geotechnical Engineering, 2014.

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