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This paper investigates the steady-state resistance (RDC) of copper tape electrodes across eight configurations. The study evaluates both field measurements and simulations using CDEGS at two distinct sites with varying soil characteristics. It emphasizes the impact of electrode size, installation sequence, and soil disturbance caused by sequential installations. Specifically, the results reveal that the first configuration, which maintained a 100% tape-to-trench ratio with no disturbance, yielded computed values within the measured range at both sites. Subsequent configurations demonstrated varying degrees of soil disturbance, affecting RDC values, particularly in high-resistivity conditions. At the low-resistivity Site 1, as the tape-to-trench ratio increased, discrepancies between measured and computed RDC values decreased, highlighting a strong dependency on electrode size and soil cohesion after backfilling. In contrast, at the high-resistivity Site 2, RDC values remained relatively stable with increasing tape-to-trench ratio, likely due to lower soil cohesion and higher air void presence. These findings underscore the importance of considering soil disturbance effects in computational models to enhance the accuracy of RDC predictions and optimize grounding performance. [ABSTRACT FROM AUTHOR]

In addition to the soil resistivity and size of the grounding system, grounding system configuration can influence the steady-state resistance (RDC) of a grounding system. The RDC of four to six configurations in three distinct soil conditions (sites 1 to 3) is measured using the fall-of-potential method and computed using the current distribution, electromagnetic fields, grounding, and soil structure analysis (CDEGS) simulation. The RDC value generally decreases as size increases, i.e., when more rods or tapes are added, except for a little variation subject to the electrode arrangement and soil resistivity. The 3 and 4-parallel configurations perform better on low resistivity soil (site 1), while the grid configurations (2×2- and 3-rod grids) are better on high resistivity soil (site 2). The difference between the measured and computed values at high soil resistivity sites (sites 2 and 3) is large, ranging from 18% to 66% for site 2 and from 35% to 53% for site 3. The difference is lower and more consistent at site 1, where five out of six configurations achieve less than 10%. At all sites, the difference between computed and measured RDCs generally decreases as the area of the electrode increases, except for some cases at site 2. [ABSTRACT FROM AUTHOR]

Grounding enhancement material (GEM) is used to lower the earthing resistance value of a given earthing system. In this paper, a commercially available GEM is experimented at the field alongside with Sodium Chloride, Copper II Sulphate and planting soil. The well established Wenner's 4 pole method and fall of potential method was employed to measure the soil resistivity and earthing resistance respectively. It was found that the salts i.e., Sodium Chloride and Copper II Sulphate are superior in reducing the earthing resistance as reduction of more than 85% were observed. However, the commercial GEM has exhibited the most stable earthing resistance value over a period of 101 days, exhibiting the lowest standard deviation. This seems to suggest that the commercial GEM has superior moisture retention capability. This study also proven that Sodium Chloride can be dissolved by heavy downpour and replenishing it periodically is needed in a tropical country like Malaysia with regular thunderstorms and heavy downpours. [ABSTRACT FROM AUTHOR]

This paper presents the transient behavior of an earthing system under the influence of lightning current injected in to it. Vertical rods and horizontal electrodes buried in homogeneous soil are considered in this analysis. State-space representation (SSR)-based transmission line methodology (TLM) is adopted with nonlinear parameters for modeling the earthing electrodes in the time domain. Soil ionization phenomenon is taken up with the presence of residual resistivity. In this method, soil resistivity variation is adopted to evaluate the soil ionization phenomenon that occurs due to changes in the electric field. This study incorporates mutual coupling between the electrode segments for low and high soil resistivity. Earthing electrodes are subjected to high-magnitude lightning current impulse with different peaks. Transient voltage and impulse impedance are calculated to analyze the transient behavior of earthing electrodes with soil ionization. The impulse impedance of vertical earthing rods and horizontal electrodes is calculated and compared with the power frequency impedance. Percentage ohmic reduction between them is also reported. The influences of a critical electric field, soil resistivity and lightning magnitude on the transient performance of earthing electrodes are calculated. Also, an effect of the front time of lightning current impulse for a fixed peak on the impedance of the earthing electrode is evaluated and significant changes are observed. Simulated results are validated with the experimental and theoretical results reported in the literature, and adequate agreements are achieved. [ABSTRACT FROM AUTHOR]

Desiccation cracking is a common and natural phenomenon under a drought climate. The geometric and morphologic characteristics of the crack pattern are critical to understanding the response of soil mechanical and hydraulic properties to drought climate. It is always a big challenge to obtain the refined geometric structure of the in-situ soil desiccation crack network. This study proposes an integrated method named ERT+ for determining the three-dimensional geometry of in-situ soil desiccation crack networks by integrating multi-source data from electrical resistivity tomography (ERT), surface image analysis, and depth investigation. The proposed method was applied to three in-situ expansive soil sites with different crack geometries and soil properties. The results showed that the joint application of ERT with other investigations reduced the ambiguity of interpreting each technique independently. The crack network model characterized the three-dimensional geometric structure of the desiccation crack accurately and quantitatively, verifying the effectiveness and feasibility of the ERT+ method. Field and laboratory experiments showed that heterogeneity in soil properties resulted in different cracking morphologies (width, depth, and width-depth ratio). The crack geometric data suggested that the width-depth ratio of the crack network was related to the cracking modes and the soil properties, indicating the non-homology of different crack networks. In addition, the correction gradients calculated from the ERT+ method also varied with the cracking modes and soil properties, further suggesting the reliability and prospect of the proposed method.

This paper investigates the steady-state resistance (RDC) of copper tape electrodes across eight configurations. The study evaluates both field measurements and simulations using CDEGS at two distinct sites with varying soil characteristics. It emphasizes the impact of electrode size, installation sequence, and soil disturbance caused by sequential installations. Specifically, the results reveal that the first configuration, which maintained a 100% tape-to-trench ratio with no disturbance, yielded computed values within the measured range at both sites. Subsequent configurations demonstrated varying degrees of soil disturbance, affecting RDC values, particularly in high-resistivity conditions. At the low-resistivity Site 1, as the tape-to-trench ratio increased, discrepancies between measured and computed RDC values decreased, highlighting a strong dependency on electrode size and soil cohesion after backfilling. In contrast, at the high-resistivity Site 2, RDC values remained relatively stable with increasing tape-to-trench ratio, likely due to lower soil cohesion and higher air void presence. These findings underscore the importance of considering soil disturbance effects in computational models to enhance the accuracy of RDC predictions and optimize grounding performance.

Groundwater in India is a critical resource, particularly in semi-arid regions of the country like Rajasthan. The deteriorated quality of surface water has led to the over-exploitation of groundwater, resulting in the drying up of shallow wells and deepening of groundwater levels. The increasing demand for water and drilling cost for boreholes have generated a prior need for exploration, monitoring, and assessment of groundwater aquifers in water-scarce agriculture-intensive areas. Identifying suitable aquifers is important; however, the emissions associated with the extraction of water from these aquifers should not be overlooked as fuel-aided extraction is a significant source of carbon emissions. A geophysical investigation based on electrical resistivity imaging using the dipole–dipole configuration was conducted in the agricultural belt of Alwar district, Rajasthan to detect aquifer depth and its hydrogeological characteristics. Resistivity survey data indicate the presence of a shallow alluvial aquifer at a depth of 9 m. The resistivity of the aquifer ranges from 15 to 84 Ωm, indicating that the soil is saturated with water in its weathered layer with a thin clay layer surrounding the saturated water zones. The groundwater and surface water represent high chemical variability which depicts that groundwater has deep meteoric percolation and subsurface geology has played a key role in regulating the water quality. Further, it was observed that electric and diesel pumps contribute significantly to carbon footprint with the values ranging from 249 to 1476 kgC/ha-yr and 60 to 266 kgC/ha-yr, respectively. Solar pumps can be a sustainable option to meet the target toward decarbonization with no emissions involved. The study concludes that solar pumping of groundwater is an important intervention for decarbonisation in agriculture sector along with judicious management interventions, improved methods of irrigation, and sustainable use of groundwater to ensure water availability and environmental quality in the region. [ABSTRACT FROM AUTHOR]

When a high magnitude of current is discharged to the ground, a large potential gradient will result in a ground potential rise (GPR, or induced voltage. This GPR usually decreases with distances, depending on the soil resistivity, ground electrode sizes, configurations and steady state resistanceRDC values. The GPR value not only provides an information on the safe distance of the nearby equipment to the grounded electrical systems subjected to impulse conditions, but can also identify the right rating of the equipment, particularly sensitive electronic equipment, that are in a vicinity of the ground installations. Further, during the high voltage testing on the ground electrodes at field sites, the results may also be influenced by the electrodes under tests, which can cause inaccuracy in the measurements. This paper is therefore aimed to measure the GPR, where the measured results are still found to be limited in literature, for various soil resistivity and ground electrodes. The measured GPR values are obtained by injecting high magnitudes of impulse current of both impulse polarities on the ground electrode, and the voltage magnitudes at distances away from the edge of the electrode under impulse are measured. The measurements of GPR allows the investigations on the effect of impulse polarity on these GPR values, which cannot be obtained by computational method. [ABSTRACT FROM AUTHOR]

Microbially induced calcium carbonate precipitation (MICP) is a promising biomediated soil improvement technique. Compared with traditional ground improvement methods, MICP has proven extensive applicability and ecological benefits. However, heterogeneity during MICP treatment is a major obstacle in engineering applications, causing a strong need for monitoring methods to investigate the process of treatment and optimize the subsequent design scheme. Electrical resistivity tomography (ERT) is a noninvasive spatially resolved monitoring technique for visualizing the distribution of both treatment solution and precipitated calcium carbonate in MICP treatment. In this study, three-dimensional electrical resistivity tomography was employed to monitor the biocementation process of a sand-packed column. The electrical response over different treatment stages and the final CaCO3 content were collected. Three-dimensional resistivity distribution intuitively characterizes the distribution of treatment solution in the sand column. Changes in the resistivity indicate the spatial variability of the urea hydrolysis and CaCO3 precipitation during the MICP treatment. The final resistivity distribution corresponds to the distribution of precipitated CaCO3 , and the relationship between electrical resistivity and CaCO3 content is established. The study serves to explore the potential of ERT as a monitoring method for the MICP treatment process. Of particular interest are its possibilities to contribute to the monitoring of spatial heterogeneity of cementation because of the limitations of traditional techniques in this respect. [ABSTRACT FROM AUTHOR]

Drought-induced clayey soil desiccation cracking is a common natural phenomenon. The presence of cracks can significantly alter the mechanical and hydraulic properties of clayey soils, and cause a series of engineering problems or hazards. Electrical resistivity tomography (ERT) is a sensitive and non-destructive technique capable of imaging the spatiotemporal resistivity variations in cracked soil. This study presents a novel ERT-based method integrating numerical modeling and experimental test to characterize the cracking morphology and quantify the cracking depth. Soil images synchronously taken record the crack morphology in the soil body during drying. Experimental results indicate the desiccation cracking patterns can be effectively reflected by the measured electrical resistance curves, implying that ERT can capture the subsurface soil cracking process. The relative variation rate of resistivity improves the accuracy of ERT in imaging the crack morphology. Furthermore, the cracking depths estimated using ERT are consistent with experimental observation. This study is expected to introduce a scheme based on ERT for monitoring the real-time evolution of clayey soil desiccation cracking and provide insights on managing and controlling the stability and performance of earth structures. [ABSTRACT FROM AUTHOR]

Electrical resistivity measurement is a quick and non-destructive method to characterize various materials in different applications. Compared to field and laboratory tests, predicting the soil properties from resistivity monitoring becomes an attractive alternative for engineering practice. The electrical resistivity of soil is sensitive to the physical–chemical soil properties, chemical activity of the pore fluid, weather and environmental conditions, and test frequency Thus, the main challenge consists in defining a reliable methodology and models to deal with so many variables. The objectives of the current study were to collect data from different geological formations and to correlate the electrical resistivity to the soil properties. In this study, over 400 data from several research studies were used to characterize the relevance of the various parameters. A new hyperbolic model was developed and compared with the power and exponential expressions to define the best-fitting model. The coarse fraction, the type and percentage of clay minerals, and the water content are the main parameters that control soil resistivity. The relationships between soil resistivity and degree of saturation, which incorporates both the soil structure and water content, revealed the best curve fitting and yet with no dependence on the compaction energy. The influence of temperature is suppressed by normalizing the electrical resistivity to the corresponding value at a standard temperature. Vipulanandan hyperbolic correlation provided better curve fittings with coefficients of determination ( R 2 ) above 0.9. [ABSTRACT FROM AUTHOR]

The current techniques utilized for estimating seasonal fluctuations in earthing system resistance, including artificial neural networks (ANNs) and correlation/correction factors, rely on resistance records, soil resistivity measurements, and meteorological data collected across broad areas. However, they frequently fail to consider the impact of soil conditions and properties at the actual earthing location. As a solution, this research introduces a new method that models atmospheric conditions as soil suction and incorporates hydraulic soil properties (soil water retention characteristics and hydraulic conductivity) to estimate the seasonal changes in earthing resistance and performance. To illustrate this approach, this study constructs geometric models of vertical earthing rods for three homogeneous soil textures (clayey, silty, and sandy) utilizing COMSOL Multiphysics software. By coupling the differential equations governing electric current and water flow using Archie's formula and solving numerically with the finite element method (FEM) for various soil suctions, this research reveals that soil water retention and resistivity variations are notably influenced by soil texture. Sandy soil displays higher variability, silt soil demonstrates moderate changes, while clayey soil exhibits lower fluctuation. By linking soil resistivity changes to soil suction and hydraulic properties, this innovative method predicts seasonal trends in earthing resistance and performance. [ABSTRACT FROM AUTHOR]

【Objective】 Crop growth and ecological functions in arid and semi-arid loess regions in northwestern China are limited not only by topsoil water directly available to crop but by deep soil water which functions as a reservoir. Slopes and lands formed by artificial retaining are two typical geographical units in small watersheds in the loess plateau. This paper presents a method to estimate soil water distribution in them up to 12.5 m deep. 【Method】 The method was based on electrical resistivity tomography (ERT). We measured electrical resistivity of the soil in typical slope and retained land in the small Liudaogou watershed in northern Shaanxi province. Using the measured soil volumetric water content, a power function relating the resistivity to soil water content was established, from which we calculated water distribution and water storage in the 0~12.5 m profile in both the slope and the retained land. 【Result】 The distribution of electrical resistivity over the slope was significantly affected by slope position, with the resistivity decreasing gradually from the slope top to the slope toe. Such changes were associated with vegetation consumption of the topsoil water and redistribution of the infiltrated precipitation over the slope. The vertical distribution of the resistivity in the retained land showed a high-low-high variation; this was also related to root water uptake from the topsoil and precipitation recharge to the subsoil. ERT inversion showed co-existence of a saturated zone and an unsaturated zone in the retained land, while the slope was partly saturated. In a 1.8×104 m2 of retained land, there was 1.49×104 m3 of water in the 0~6.5 m unsaturated layer, and 5.10×104 m3 of water in the saturated layer. In a same area but on the slope, there was only 2.59×104 m3 of water in the 0~12.5 m soil layer. 【Conclusion】 Retained land contains more water than slope, and the deep soil in it functions as a reservoir banking infiltration water in wet seasons. ERT is suitable for measuring spatiotemporal variation in soil moisture in both slopes and flatten plains in the loess plateau.

In order to solve the reverse distribution of energy and demand in China, ultra high voltage direct current transmission (UHVDC), which has significant advantages such as large transmission capacity, low line loss and long transmission distance, has become an important scheme. However, due to its long transmission distance, complex terrain and climate across the region, the distribution of soil resistivity along the line is uneven. Based on Zhundong-Wannan ± 1 100 kV UHVDC transmission project, the overvoltage mechanism of DC line was analyzed. The electromagnetic transient calculation software PSCAD was used to simulate and analyze the overvoltage of DC line with different average soil resistivity and actual soil resistivity in four seasons. The results show that the soil resistivity will affect the reflection of the converter station, and the actual soil resistivity will make the maximum overvoltage position shift towards the transmitting side. It is concluded that the overvoltage suppression effect is better by optimizing the installation position of line arrester, which provides an important reference for the development of UHVDC transmission project. [ABSTRACT FROM AUTHOR]

The corrosion behavior of carbon steel X36 (CSX36) in solutions of soils collected from different areas linked to the main pipe network of a water distribution system in Jeddah City (Obhour Al Shamaliyah, Ob-Sh; Al Shateie, Sh; Al Safa, Sf; Al Samer, Sa; and Al Jameaah, Ja) at an ambient temperature (23 ± 1 °C) was studied. The corrosion behavior was monitored using various techniques, such as weight loss and electrochemical (open circuit potential [OCP]; electrochemical impedance spectroscopy; and potentiodynamic polarization) measurements. Visual and microscopic examinations of the surface morphology of the studied metals were evaluated and discussed. The corrosion rates in all the studied soil solutions decreased with an increase in the immersion period over 80 weeks. The corrosivity of the studied soils based on weight loss measurements followed the order Sh > Ja > Ob-Sh > Sa > Sf. The value of the OCP gradually shifted to more negative values, indicating a higher tendency to corrode. For the soil solutions studied, the Ecorr shifted to more negative values, indicating that the corrosion process was under cathodic control. The values of icorr and 1/Rp tended to increase as the soil resistivity decreased. Moreover, there was good consistency between the corrosivity order of the studied soil solution obtained from electrochemical impedance spectroscopy and PDP measurements in the following order: Ob-Sh > Sh > Ja > Sa > Sf. A comprehensive assessment of the soil corrosivity based on various soil variables revealed that soil solutions of Ob-Sh and Sh are extremely corrosive, while the rest of the soil solutions are noncorrosive. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Shading on PV panels impacts system output power. • Adequate lightning protection reduces the risk of damage during storm conditions. • Lightning masts are crucial for PV system compliance with standards. Globally, solar energy technologies are increasingly being implemented. The appeal of photovoltaic (PV) systems lies in their ability to efficiently convert sunlight into electricity, making them popular among homeowners, manufacturers, and businesses. To maximize the output of a PV system, it is crucial to install the panels in a location with ample sunlight exposure and minimal shading. Typically, PV panels are mounted on rooftops to avoid shading which exposes the system to the risk of lightning strikes during storms. To mitigate this risk, engineers implement direct lightning protection measures. This paper focuses solely on direct lightning protection methods, discussing the importance of the earth grid and the factors influencing its effectiveness. Additionally, the paper introduces a new layout for lightning masts for PV systems with back-to-back east and west panel orientations where space constraints limit the separation of PV rows. This approach is considered novel as it cannot be found in any published peer-reviewed works. A detailed case study is also presented which supports the introduced equations when it comes to design and compliance to direct lightning strikes. Additionally, the implementation of equations 2 to 12 simplifies the work for designers to ensure lightning compliance using the rolling sphere method. [ABSTRACT FROM AUTHOR]

Inspection and assessment of ageing buried metallic infrastructure such as pipelines can be costly, especially when soil sampling programs are involved to evaluate large networks and pipe health conditions. In order to reduce these costs through assessment prioritisation at infrastructure locations that are scientifically inferred to be under highly corroded state, advancements in current approaches are necessary. In this study we have investigated the utility of soil resistivity as an index for buried and ageing pipe health status through numerical and field case studies. Numerical study showed that the monotonous relationship between soil resistivity and maximum pit depth that is often considered in literature as linear is actually non-linear. Field study involving in-situ wall thickness measurements of 3 separate water distribution mains (each > 1.5 km in length) at selected excavated locations were compared with the saturated soil resistivity (ρsat) acquired a-prior. The ρsat was found to be highly correlated to the maximum corrosion pit depths observed in-situ. This correspondence is argued to exist provided the saturated soil resistivity displays statistical uniformity along the pipe and the pipes are not under submerged conditions. Locations on the pipe where ρsat < 15 Ω m were found to have corroded relatively more than other locations; in one instant a leaking pipe due to excessive corrosion was also observed. A practical indirect assessment framework was proposed that can be utilised immediately in professional practice.

In order to overcome the shortcomings of fuzziness, randomness and interaction between the soil corrosion factors of buried pipeline, as well as the low accuracy of prediction with the traditional methods, a prediction model of external corrosion rate was established with 10 influencing factors as the input, and the external corrosion rate as the output based on the field data of corrosion coupons of a buried pipeline. Thereby, the data samples were trained, verified and tested using the Radial Basis Function (RBF) neural network mode, and the key parameters affecting the corrosion were identified through Sobol sensitivity analysis. The results show that the mean square error is 0.000 99 when 10-35-1 type RBF model is iterated to step 2 273, and the correlation coefficients of the training, validation and testing stages are 0.970 7, 0.981 3 and 0.990 1 respectively. Compared with BP, MLR and SVM models, the average relative error of RBF neural network model is 2.07%, indicating that RBF neural network model has some advantages in terms of the external corrosion rate prediction of buried pipeline. The soil resistivity has the maximum effect on the external corrosion rate. Moreover, the soil resistivity, pH value, and Cl- content significantly interact with other factors, which should be paid much more attention. Generally, the established model can be effectively applied to the external corrosion rate prediction of pipeline, and the results could provide theoretical basis and reference for pipeline integrity management.

An efficient method for evaluation of an optimal two-layer soil model from Wenner four-probe measuring method, which has been used during experimental investigations, is presented within this paper. A two-layer soil model is assumed, and this soil model is an adequate representation of nonhomogeneous soil for grounding system design. The application of optimization techniques is required to estimate the electrical parameters of the proposed soil model. In this paper, first the fast gradient-descent method to solve a given optimization problem is chosen, and then with the aim of faster calculation for accelerating the rate of convergence of an infinite sum, the application of Aitken's δ² method is proposed. [ABSTRACT FROM AUTHOR]

This article presented the characteristics of the grounding electrodes in uniform and two layer soils when subjected to lightning including the impacts of soil ionization with frequency, soil resistivity, and permittivity variations. The critical breakdown field strength of two layer soils with different values of the reflection factors was presented. The transient probabilistic grounding potential rise and the transient impedances of the horizontal and vertical electrodes were investigated in uniform and two layer soils including the effect of soil ionization with frequency. Finally, the influences of resistivity and permittivity variations which have substantial impacts on the electric field at the occurrence of the soil ionization were considered. Moreover, transmission line approach (TL) with the aid of ATP has been used to compute the transient grounding voltages. The results indicated that the reflection factor has a significant impact on the equivalent radius of the grounding electrode. It is also observed that the peak values of the lightning induced voltages decreases sharply when the soil ionization phenomenon considering the variations in soil resistivity and permittivity with the stroke frequency changes. Furthermore, the impedances of the burial electrodes that have negative reflection factors were lower than that in case of positive reflection factors.

Soil resistivity is an important parameter for designing electrical earthing system. The measurement of soil resistivity is greatly influenced by moisture content, temperature, porosity, degree of saturation, number of soil layer(s), and frequency of lightning current. Researchers have proposed various methodologies to provide an approximation of soil resistivity using the listed parameters. In order to ease the process of estimating soil resistivity at a particular area, there is a pressing need to devise a simple tool that enables the calculation of soil resistivity in the most accurate manner. As such, this research proposes a reliable tool for quick evaluation of soil resistivity based on variousmethodologies using Microsoft Excel’s built-in-functions and Visual Basic Application (VBA) Next, the developed tool was validated using two methods, in which the output value of the calculator was compared with data retrieved from IEEE Std 142-2007 and data reported in past studies. The validation results revealed that the developed calculator may serve as a significant application in future due to its time-saving and cost-effective attributes.

• A method for characterizing 3D geometrics of soil desiccation cracks is proposed. • Multi-source data from ERT and image analysis reduce the ambiguity of each method. • The method is applied to field sites and shows particular robustness. Desiccation cracking is a common and natural phenomenon under a drought climate. The geometric and morphologic characteristics of the crack pattern are critical to understanding the response of soil mechanical and hydraulic properties to drought climate. It is always a big challenge to obtain the refined geometric structure of the in-situ soil desiccation crack network. This study proposes an integrated method named ERT+ for determining the three-dimensional geometry of in-situ soil desiccation crack networks by integrating multi-source data from electrical resistivity tomography (ERT), surface image analysis, and depth investigation. The proposed method was applied to three in-situ expansive soil sites with different crack geometries and soil properties. The results showed that the joint application of ERT with other investigations reduced the ambiguity of interpreting each technique independently. The crack network model characterized the three-dimensional geometric structure of the desiccation crack accurately and quantitatively, verifying the effectiveness and feasibility of the ERT+ method. Field and laboratory experiments showed that heterogeneity in soil properties resulted in different cracking morphologies (width, depth, and width-depth ratio). The crack geometric data suggested that the width-depth ratio of the crack network was related to the cracking modes and the soil properties, indicating the non-homology of different crack networks. In addition, the correction gradients calculated from the ERT+ method also varied with the cracking modes and soil properties, further suggesting the reliability and prospect of the proposed method. [ABSTRACT FROM AUTHOR]

• Original methodology for determining the frequency dependence of electric parameters. • Frequency dependent soil resistivity and permittivity. • Investigating the use of other shapes/dimensions of electrodes. • Electric parameters of soil to the measured harmonic impedance of a portion of soil by a geometric factor. • Determining the geometric factor of short tubes. This work proposes the improvement of the original methodology for determining the frequency dependence of electric parameters of soil from field measurements, proposed by Visacro and Alipio, by using a different electrode, consisting of a short tube buried in the ground, and a respective geometric factor to allow determining the frequency dependent resistivity and permittivity. A numerical method was developed and applied for determining this geometric factor, whose validation was assessed using an electromagnetic model. The proposed improvement makes the implementation of the methodology much simpler and faster, favoring the reliability of results, overall in applications with high accuracy requirements. [ABSTRACT FROM AUTHOR]

• Measured transient resistivity ρ(t) is a continuous function over a wide time range, 100 ns ≤ t ≤ 1 s. • Transient resistivity can be measured with four-probe (Wenner, Schlumberger) methods. • Transient resistivity should be measured using hemispherical electrodes and square waves. • The recommended three-terminal oblique test geometry responds predictably in two-layer soil. • An expected dual relation ρ(t) to ρ(f) is seen in soil of low and high resistivity. Models of frequency-dependent soil resistivity ρ(f) suggest the dual concept of time-dependent resistivity ρ(t) that, for high resistivity soil, increases from 100 ns to 100 μs, a range of time relevant for lightning backflashover performance calculations. Measurements of ρ(t) can be made by impressing impulse or step current and monitoring voltage rise. Time-dependent resistivity can be established with Wenner or Schlumberger probe arrays and also with oblique fall-of-potential measurements from buried hemispheres. Tests show that rectangular and double-exponential pulse currents both have value. Specialized evaluation using "Drained Net Charge" concepts may yield estimates of low-frequency resistivity ρ o. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Measurement Science & Instrumentation is the property of Journal of Measurement Science & Instrumentation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the present study, field tests were performed using low-resistivity materials (LRMs) in different grounding system (GS) configurations to reduce the grounding resistance (GR) and assess the variation in the effectiveness of the LRMs with increases in the complexity of the GS design. Different configurations were implemented in soils with different resistivity values to determine the variation in the effectiveness of each LRM design with increases in the soil resistivity. Lastly, the percentage decrease in the GR was assessed as a function of the increase in the complexity of the GS design and the variation in the soil resistivity. The results of this study provide a useful guide for engineers and researchers who study, design, and build innovative and effective GSs by applying improved compounds for safe electrical installations. [ABSTRACT FROM AUTHOR]

In order to protect the transmission lines against lightning strikes, it is important to investigate the tower grounding system. In this paper, a recent method called hybrid continuous circuit-trapezoidal integration method is used to calculate the impulse impedance of the grounding system. Moreover, conventional structures of the grounding systems have been simulated and the results show that, with the same wire length, the square with additional wire system has the least impulse impedance as compared to counterpoise, square and crow’s foot. Moreover, the effects of soil resistivity and lightning current rise-time on the impulse impedance of these grounding systems are investigated. It is concluded that the design of the grounding system depends on the geographic location of the site in terms of soil resistivity and isotropic characteristics of the area in terms of lightning current rise-time.

Soil resistivity is an important soil property that affects the selection of grounding electrode sites for HVDC transmission. How to quickly obtain the spatial distribution of soil resistivity and provide reference for the selection of grounding electrode sites is an important issue in HVDC transmission. This paper takes part of Shanxi Province and Fugu County, Yulin City, Shaanxi Province as the study area. The Sentinel-1, Sentinel-2 and SMAP satellite data are used to retrieve the soil volumetric water content in the study area, and the spatial distribution of soil gravimetric water content is obtained by combining the soil bulk density with volumetric water content. Finally, the estimation model is established by the field measurements of soil resistivity and soil gravimetric water content estimated based on remote sensing. Through the estimation model, the fitting relationship between soil resistivity and soil gravimetric water content in the form of power function is obtained, and the distribution of soil resistivity at the grounding electrode sites to be selected and its surrounding areas is obtained. The results show that remote sensing can assist in the selection of grounding electrode sites, which provides a new idea for the selection of grounding electrode sites in a large range of areas. [ABSTRACT FROM AUTHOR]

In view of problems of limited terrain, short effective dispersion length, and low resistance reduction efficiency in the extensional resistance reduction of the grounding grid of incoming line section of mine substation, a resistance reduction method using long -distance extension lead for auxiliary grounding of incoming line tower was proposed. The grounding calculation software CDEGS is used to establish simulation model of 'Τ' type, 'Γ' type, box type, vertical type unidirectional auxiliary grounding network, and study stray current characteristics of unidirectional auxiliary grounding grid of steel tube tower and corresponding influencing factors. The research results show that the longer the extension lead, the higher the resistance reduction efficiency; when the extension lead length exceeds 60 m, the resistance reduction efficiency is stable at about 80% under the action of high -frequency current; the 'Γ' type unidirectional auxiliary grounding grid has stable stray current characteristics, strong shunting ability, and its resistance reduction effect is the best; resistance reduction efficiency of the unidirectional auxiliary grounding grid is more than 70% under different soil conditions. In practical engineering applications, it is recommended to determine the extension lead length and terminal structure of the auxiliary grounding grid according to the actual soil conditions, and to lay the auxiliary grounding grid to areas with low soil resistivity or to take local soil replacement measures for areas with high soil resistivity to improve the resistance reduction efficiency of unidirectional auxiliary grounding grid of the incoming line tower.

Research relevance. One of the main causes of high accidents and outages in distributed power supply systems of 6(10) kV oil well clusters is damage to overhead power lines due to single-phase ground faults. Widely conducted researches to determine the location of a single-phase ground fault have established a correlation between the determination accuracy and a large number of changing factors, such as operating mode parameters, overhead power line parameters, damage type, transition resistance, soil resistance, and taking their average values, regardless of changing climatic conditions. Rationing of technical means for determining the location of a single-phase ground fault according to instrumental errors without taking into account the methodological component defines the error in determining the location of the damage, reaching 30 %. Thus, the relevant research is aimed at determining the primary parameters of transmission lines and minimizing the methodological error in defining the location of damage to transmission lines considering climatic factors. The main aim of the research is to improve the accuracy of determining the location of a single-phase ground fault of a 6 (10) kV transmission line with developing a methodology that takes into account the influence of climatic factors. Research methods. The basic physical processes of propagation of an electromagnetic wave in a power line are taken into account. The main principles of the theory of electrical circuits and the electromagnetic field are used; MATLAB Simulink package algorithms. Research results. The authors have developed the algorithm that allows determining the distance from 6(10)/0,4 kV substations to the point of single-phase ground fault occurrence in distribution networks of oil well clusters taking into account climatic factors. A simulation model of a 10 kV distribution network supplying oil well clusters considering the dependence of the primary transmission line parameters on climatic factors and soil resistivity, was developed in MATLAB Simulink.

The corrosion behavior of carbon steel X36 (CSX36) in solutions of soils collected from different areas linked to the main pipe network of a water distribution system in Jeddah City (Obhour Al Shamaliyah, Ob-Sh; Al Shateie, Sh; Al Safa, Sf; Al Samer, Sa; and Al Jameaah, Ja) at an ambient temperature (23 ± 1 °C) was studied. The corrosion behavior was monitored using various techniques, such as weight loss and electrochemical (open circuit potential [OCP]; electrochemical impedance spectroscopy; and potentiodynamic polarization) measurements. Visual and microscopic examinations of the surface morphology of the studied metals were evaluated and discussed. The corrosion rates in all the studied soil solutions decreased with an increase in the immersion period over 80 weeks. The corrosivity of the studied soils based on weight loss measurements followed the order Sh > Ja > Ob-Sh > Sa > Sf. The value of the OCP gradually shifted to more negative values, indicating a higher tendency to corrode. For the soil solutions studied, the Ecorr shifted to more negative values, indicating that the corrosion process was under cathodic control. The values of icorr and 1/Rp tended to increase as the soil resistivity decreased. Moreover, there was good consistency between the corrosivity order of the studied soil solution obtained from electrochemical impedance spectroscopy and PDP measurements in the following order: Ob-Sh > Sh > Ja > Sa > Sf. A comprehensive assessment of the soil corrosivity based on various soil variables revealed that soil solutions of Ob-Sh and Sh are extremely corrosive, while the rest of the soil solutions are noncorrosive.

The joint application of geophysical investigations, non-invasive methods, and geotechnical investigations, invasive methods, in order to interpret the geological features in subsurface has been increasingly accepted, however, the correlation between the values collected by the geophysical methods and the direct investigative techniques have been developed in recent years. The obtained linear relationships are site specific and complementary studies are needed to establish their validation and limitations for each site. In this study, Electrical Resistivity Tomography (ERT) was used with Standard Penetration Test (SPT) for geotechnical investigation at three hillslope sites with different tropical soil properties in Bahia, Brazil. The results from thirteen boreholes were analyzed against data from 2D inverted sections. Linear fitting successfully correlates resistivity and NSPT for one borehole. Correlations of electrical resistivity and NSPT values were also performed using soils with similar compositions and physical characteristics, which showed good results. The coefficient of correlation (R) was 0.94. In addition, results the fitting slope coefficient seems to be dependent of soil genesis (lithology, texture and clay content variation) scription obtained in SPT surveys.

Spatial information about soils generally results from local observations which are destructive and time consuming. Geophysical techniques could help soil mapping since they are non-destructive and fast. Electrical resistivity is interesting for soil studies due to a wide range of values and as it depends on soil characteristics. This work aims to study soil spatial variability using electrical resistivity. GPS defined grid points of 40X40 m were installed in the experimental western farm (EWF) in the Faculty of Agriculture of Cairo University in Giza. Electrical resistivity was measured at 40 points using 4-electrodes Wenner array in a line perpendicular to the path direction. Soil resistivity data from 2-depths profiling mode was considered to produce two apparent resistivity maps and geostatistically tested. Soil resistivity taxa were sampled and analyzed for soil moisture, EC and bulk density. Krigged soil resistivity maps were produced for depths (i.e. 30 and 60 cm). Kriging and Semivariogram interpretation was conducted, and the spatial dependency of top and subsoil resistivity were moderate (48.4% and 68.6% respectively). Highly significant negative correlations were recorded in the topsoil between apparent or true resistivity and soil moisture, EC or bulk density. The obtained models were used to produce conjugated moisture and EC maps and geostatistically investigated. The spatial dependency of the top and subsoil moisture or salinity were moderate. Soil moisture and EC are the most significant factors for controlling soil electrical resistivity. The method used opens the way to the development of semi-automatic soil mapping from electrical resistivity data.

The earthing system is very important to safe human’s lives and protect power system from normal and abnormal faults. High soil resistivity regions is the main problem of installation the earthing systems in electric power substations to pass the current through the earth's surface. This paper has been overcome on high soil resistivity regions by penetrating conductive nanoparticles to have extremely low grounding resistance. Moreover, it has been succeeded to examine the methodology of the proposed Nano-Tech earthing systems in case of single rods, multiple rods and grids. Also, it has been defined optimal types and concentrations of nanoparticles for Nano- Tech grounding system to provide excellence protection for electrical substations with respect to built beneath of soil where substation is located. A comparative study has been discussed and analyzed the results of traditional and nanotechnology grounding systems. [ABSTRACT FROM AUTHOR]

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