scholarly journals Wenner Soundings for Apparent Resistivity Measurements at Small Depths Using a Set of Unequal Bare Electrodes: Selected Case Studies

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 695 ◽  
Author(s):  
Eduardo Faleiro ◽  
Gabriel Asensio ◽  
Gregorio Denche ◽  
Daniel Garcia ◽  
Jorge Moreno
Keyword(s):  
Case Studies ◽  
Apparent Resistivity ◽  
Resistivity Measurements ◽  
Electrode Separation

The possibility of using a set of unequal electrodes, within limits, in a Wenner arrangement for the measurement of apparent resistivity at small depths is explored in this paper. A procedure in which only a simple preliminary calibration is necessary to obtain the best measurements of the apparent resistivity is proposed. On the basis of some case studies, a comparison with the usual procedures to obtain the apparent resistivity from resistance measurements is carried out. The results showed that when an unequal set of electrodes was used, the procedure proposed here was the only one that guaranteed the best apparent resistivity values for any value of electrode separation in the Wenner arrangement, especially for those associated with small depths.

scholarly journals Corrections of surface fissure effect on apparent resistivity measurements

2014 ◽  
Vol 200 (2) ◽  
pp. 1118-1135 ◽  
Author(s):  
J. Gance ◽  
P. Sailhac ◽  
J.-P. Malet
Keyword(s):  
Apparent Resistivity ◽  
Resistivity Measurements

scholarly journals Numerical Modeling of the Effects of Electrode Spacing and Multilayered Concrete Resistivity on the Apparent Resistivity Measured Using Wenner Method

2020 ◽  
Author(s):  
Karthick Thiyagarajan ◽  
Parikshit Acharya ◽  
Lasitha Piyathilaka ◽  
sarath kodagoda
Keyword(s):  
Contact Area ◽  
Apparent Resistivity ◽  
Resistivity Measurement ◽  
Gaussian Process Regression ◽  
Electrode Spacing ◽  
Electrical Resistivity Measurement ◽  
Resistivity Measurements ◽  
Electrode Contact ◽  
Concrete Resistivity ◽  
Moisture Conditions

Smart Sensing technologies can play an important role in the conditional assessment of concrete sewer pipe linings. In the long-term, the permeation of acids can deteriorate the pipe linings. Currently, there are no proven sensors available to non-invasively estimate the depth of acid permeation in real-time. The electrical resistivity measurement on the surface of the linings can indicate the sub-surface acid moisture conditions. In this study, we consider acid permeated linings as a two resistivity layer concrete sample, where the top resistivity layer is assumed to be acid permeated and the bottom resistivity layer indicates normal moisture conditions. Firstly, we modeled the sensor based on the four-probe Wenner method. The measurements of the developed model were compared with the previous studies for validation. Then, the sensor model was utilized to study the effects of electrode contact area, electrode spacing distance and two resistivity layered concrete on the apparent resistivity measurements. All the simulations were carried out by varying the thickness of top resistivity layer concrete. The simulation study indicated that the electrode contact area has very minimal effects on apparent resistivity measurements. Also, an increase in apparent resistivity measurements was observed when there is an increase in the distance of the electrode spacing. Further, a machine learning approach using Gaussian process regression modeling was formulated to estimate the depth of acid permeated layer

scholarly journals Electrical Resistivity Profiles and Temperatures in the Ross Ice Shelf

1976 ◽  
Vol 16 (74) ◽  
pp. 307-308
Author(s):  
C.R. Bentley
Keyword(s):  
Electrical Resistivity ◽  
Computer Program ◽  
Depth Profile ◽  
Apparent Resistivity ◽  
Ice Shelf ◽  
Resistivity Measurements ◽  
Ross Ice Shelf ◽  
Field Season ◽  
A Site ◽  
Temperature Depth

AbstractDuring the 1973-74 Antarctic field season, two electrical resistivity profiles were completed along directions perpendicular to each other at a site in the south-easternpart of the Ross Ice Shelf. These profiles differ from each other only at short electrode spacings (less than 10 m) indicating no measurable horizontal anisotropy below the uppermost firn zone. The shape of the apparent resistivity curves is similar to that found by Hochstein on the Ross Ice Shelf near Roosevelt Island, but is displaced toward lower resistivities despite the colder 10 m temperature (—29°C instead of —26°C) at the more southerly site. Some factor other than temperature must therefore be effective in determining the overall magnitude of the resistivities in the shelf, although the variation with depth can still be expected to be primarily a temperature phenomenon.A computer program has been written to calculate apparent resistivities based on Crary’s analysis of temperatures in an ice shelf. Results are not yet available; when completed they should indicate the sensitivity of the resistivity measurements to differences in the temperature- depth profile, and hence their usefulness in estimating bottom melt/freeze rates.

A PARADOX IN APPARENT RESISTIVITY MEASUREMENTS OVER A GROUND SECTION WITH CONDUCTIVE SUBSTRATUM

Geophysics ◽  
1974 ◽  
Vol 39 (1) ◽  
pp. 93-94 ◽  
Author(s):  
B. N. Satpathy
Keyword(s):  
Apparent Resistivity ◽  
Critical Value ◽  
Surface Electrode ◽  
Conductive Layer ◽  
Electrode Arrays ◽  
Opposite Result ◽  
Resistivity Measurements ◽  
Opposite Manner ◽  
Value Changes ◽  
Lower Resistivity

It is generally accepted that the resistivity of the top layer largely influences the apparent resistivity measured through conventional surface electrode arrays. Thus, intuitively it would be assumed that the overlaying of a conductive layer would give an apparent resistivity which is less than the value obtained without the conducting cover and an opposite result would be obtained by introducing a resistive top layer. Though this belief is valid for many geoelectric sections, it is here shown that for a two‐layer section with [Formula: see text], if the top portion of the first layer is replaced with a layer of higher or lower resistivity, the apparent resistivity value changes in an opposite manner after a critical value of the electrode separation: the apparent resistivity for large separations is decreased due to the introduction of the resistive top layer. It is intended in this note to elucidate this paradox through a suitable example.

The Effect of Glacial Cross-Section on Vertical Resistivity Depth Soundings

1973 ◽  
Vol 12 (66) ◽  
pp. 375-382
Author(s):  
R. W. Taylor ◽  
R. J. Greenfield
Keyword(s):  
Cross Section ◽  
Field Data ◽  
Apparent Resistivity ◽  
Ice Thickness ◽  
Master Curves ◽  
Glacial Ice ◽  
Resistivity Measurements ◽  
Oriented Parallel ◽  
Wenner Array

The determination of glacial ice thickness by vertical resistivity depth soundings relies upon the use of theoretical curves which neglect the effect of valley walls. To improve the utility of glacial resistivity measurements an analytical expression is derived for the apparent resistivity determined by a Wenner array oriented parallel to the strike of a layered trough embedded in a perfectly conducting half space. Numerical evaluation of this expression allows the effects of glacial cross-section to be determined. It is shown that the presence of valley walls and layering within the glacier can strongly effect the determination of total ice thickness, and a criterion for the reliable use of plane-layered master curves in the interpretation of field data is established. An apparent resistivity curve calculated for a layered trough is shown to give an excellent fit to field data published by Röthlisberger and Vögtli (1967).

THEORETICAL HORIZONTAL RESISTIVITY PROFILES OVER HEMISPHERICAL SINKS

Geophysics ◽  
1961 ◽  
Vol 26 (3) ◽  
pp. 342-354 ◽  
Author(s):  
Kenneth L. Cook ◽  
Russel L. Gray
Keyword(s):  
Digital Computer ◽  
Apparent Resistivity ◽  
Reflection Factor ◽  
General Utility ◽  
Qualitative Interpretation ◽  
Electrode Separation

An album of 40 sets (about 200 different curves) of theoretical horizontal resistivity profiles over and near outcropping hemispherical sinks shows the effects of sink diameter, reflection factor k, and distance of the traverse from the center of the sink upon the magnitude and shape of the apparent resistivity curves. Curves for sink diameters of 16a, 8a, 6a, 4a, 2a, a, and 0.5a, and reflection factors k of ±0.8, ±0.6, ±0.4, and ±0.2 are included. The values of apparent resistivity for both the Lee and Wenner configurations were computed using a digital computer. In general, the larger the sink, the larger the magnitude of the apparent resistivity anomaly up to a sink diameter of about 8a, for which the apparent resistivity over the central part of the sink is essentially equal to the resistivity of the sink, irrespective of the reflection factor. For sink diameters equal to the electrode separation a, large apparent resistivity anomalies result from “pseudo‐focusing” effects. The major peaks of the apparent resistivity curves, which lie outside the edges of the sink for negative reflection factors and inside for positive reflection factors, can be used to detect the edges of the sinks. The album of curves provides a general utility for the qualitative interpretation of apparent resistivity anomalies over features other than hemispherical sinks, such as faults (for large sinks), dikes, grabens, and similar features.

scholarly journals The Effect of Glacial Cross-Section on Vertical Resistivity Depth Soundings

1973 ◽  
Vol 12 (66) ◽  
pp. 375-382 ◽  
Author(s):  
R. W. Taylor ◽  
R. J. Greenfield
Keyword(s):  
Cross Section ◽  
Field Data ◽  
Apparent Resistivity ◽  
Ice Thickness ◽  
Master Curves ◽  
Glacial Ice ◽  
Resistivity Measurements ◽  
Oriented Parallel ◽  
Wenner Array

The determination of glacial ice thickness by vertical resistivity depth soundings relies upon the use of theoretical curves which neglect the effect of valley walls. To improve the utility of glacial resistivity measurements an analytical expression is derived for the apparent resistivity determined by a Wenner array oriented parallel to the strike of a layered trough embedded in a perfectly conducting half space. Numerical evaluation of this expression allows the effects of glacial cross-section to be determined. It is shown that the presence of valley walls and layering within the glacier can strongly effect the determination of total ice thickness, and a criterion for the reliable use of plane-layered master curves in the interpretation of field data is established. An apparent resistivity curve calculated for a layered trough is shown to give an excellent fit to field data published by Röthlisberger and Vögtli (1967).

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