Standard Test Method for Field Measurement of Soil Resistivity Using the Wenner Four-Electrode Method. Soil testing is performed for a variety of reasons, from agricultural to environmental. Find out why the ASTM G57 standard may be helpful for. Geotechnical and power engineers, find out how to perform a fall-of-potential or ASTM G57 test.
|Published (Last):||23 July 2017|
|PDF File Size:||15.58 Mb|
|ePub File Size:||15.93 Mb|
|Price:||Free* [*Free Regsitration Required]|
Using dimensional analysis, the correct unit for resistivity is ohm-centimetre. The resulting resistivity measurement represents the average resistivity of a hemisphere of soil of a radius equal to the electrode separation. It is desirable to sample each type separately.
The two-electrode technique is inherently less accurate than the four-electrode method because of polarization effects, but useful information can be obtained concerning the characteristics of b57 strata.
The box should be readily cleanable to avoid contamination by previous samples. A galvanometer type of movement is preferred but an electronic type instrument will yield satisfactory results if the meter input impedance is at least 10 megaohm. The mean and median resistivity values will indicate the general corrosivity of the soil.
ASTM G57 Standard
Surface contamination tends to concentrate in existing ditches with surface run-off, appreciably lowering the resistivity below the natural level. When a metallic structure is immersed in aetm conductive medium, the ability of the medium to carry current will in? The multiparticipant test program results indicate a reproducibility Cv of If samples are retained for subsequent measurement, correct the resistivity if the measurement temperature is substantially different from the ground temperature.
G5 effect of variations in compaction and moisture content can be reduced by fully saturating the sample before placing it in the box.
A soil box can be calibrated using solutions of known ast. Last previous edition G 57 — Available pedological data should be used to facilitate interpretation. The soil should be well-compacted in layers in the soil box, with air spaces eliminated asfm far as practicable.
The latter method permits precise mathematical treatment, such as cumulative probability analysis. Summary of Test Method 3. Where regular surveys are to be made at? Measurements could be made in each soil classi?
A superscript epsilon e indicates an editorial change since the last revision or reapproval. The electrodes should be formed with a handle and a FIG.
ASTM Ga (Reapproved )_百度文库
Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm. A number in parentheses indicates the v57 of last reapproval. Originally published as G 57 — An unaltered dc source can be used if the electrodes are abraded to bright metal before immersion, asgm is regularly reversed during measurement, and measurements are averaged for each polarity.
A summary of these data is given astn Table 1. If error exceeds this limit, prepare a calibration curve and correct all measurements accordingly. NOTE 1—The spacing between the inner electrodes should be measured from the inner edges of the electrode pins, and not from the center of the electrodes.
Active Risk Management
The ashm method is suited to graphical presentation and plotting resistivity versus distance, and will identify gradients and abrupt changes in soil condition. In the case of soil resistivity measurements reproducibility may be characterized by a coefficient of variation, Cv, representing the reproducibility standard deviation astk by the average result and expressed in percent.
The current can be provided by either a cranked ac generator or a vibrator-equipped dc source. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below. The multi-participant test program results indicate a repeatability Cv of 6. Measure the voltage drop across the inner electrodes and record both the current and voltage drop if a separate ammeter and voltmeter are used.
Otherwise, use distilled water. Where resistivity information is included in published aastm, the measurement techniques used should be de? Since a pipeline ditch cannot be included in the span of at-grade measurements, soil box samples should be obtained where the opportunity exists. Sharp changes in resistivity with distance and appreciable variations in moisture content and drainage are indicative of local severe conditions.
Both astk may require heat treatment so that they are sufficiently rigid to be inserted in dry or gravel soils.
Do not include large nonconductive bodies such as h57 soil, boulders, concrete foundations, etc. Alternatively, the resistance can be measured directly. Since the number of soil sections that could be inspected is essentially unlimited, in?
It is the responsibility of the user of this standard to establish appropriate safety astn health practices asrm determine the applicability of regulatory limitations prior to use. Precision and Bias 9. The a spacing should equal the maximum depth of interest. Where a resistivity meter is used, read the resistance directly and record. In either case, use pedological surveys in the planning and interpretation of any extensive survey.
It will also be necessary to prepare a mixed sample. To evaluate contamination effects when a new route is being evaluated, soil samples can be obtained at crossings of existing pipelines, cables, etc, or by intentional sampling using soil augers.
Planning and Interpretation 7. In the case of soil resistivity measurements, the repeatability may be characterized by a coefficient of variation, Cv, representing the repeatability standard deviation divided by the average result and expressed in percent.