Soil Resistivity Research Articles

Axle Counter Grounding System on The PPI Madiun Railway Using the Wenner Method

Axle counter is a railway detection equipment producing wave frequencies to count the number of axles passing over the track. The existence of a mismatch between the initial and final count numbers usually leads to a red signal and this can prevent the formation of a travel route. The components of axle counter are often damaged by lightning strikes both directly and through the distribution of excessive currents due to a poor grounding system. However, these excessive currents can be safely grounded without damaging the components through the application of a good grounding system. Therefore, this research aimed to plan an effective grounding system to anticipate the incidents using the Wenner method. Some requirements such as soil type, depth, and electrode rod diameter were used in the process to determine the appropriate resistance value. The design was made based on the simulations that closely resembled real field conditions using Aspix software and grounding resistance values were also measured directly on the field to determine the discrepancies between the planning and actual conditions.

Effect of different water and organic matter content on the resistivity of loess

The pore structure and strength of loess itself will change significantly in the process of mixing organic matter, which, as the main component of solid waste at present, is of great significance for ecological vegetation restoration in loess areas. At present, the research on the internal structure and strength performance of loess through the content of organic matter is still less, this paper takes the loess mixed with different content of organic matter (0 %–6 %) and distilled water (12 %–24 %) as the object of research, and tests the electrical resistivity and pore structure of the doped organic matter loess through the LCR digital bridge test equipment and liquid nitrogen adsorption experiments. The results show that the organic matter content and water content are important factors affecting the change of resistivity of organic soil. The electrical resistivity of organic soil is correlated with its own water content and organic matter content, which is closely related to the pore type and specific surface area within the organic soil. The results of the study provide valuable references for vegetation restoration and land use and conservation strategies in ecosystems.

Determination of Infiltration Rate Capacity of Minor Irrigation (M. I) Tanks in Gangakatwa Stream Basin over Lateritic, Basaltic and Granitic formations in parts of Vikarabad and Sangareddy District - Telagana State, India.

The study focused on determining the infiltration rate capacity of three Minor Irrigation tanks in the Gangakatwa stream basin in Telangana State, India, which were located in areas with laterite, basalt, and granite formations. Geophysical Resistivity Surveys, (Vertical Electrical Sounding) were conducted parallel to the bund to determine the soil resistivity. Three locations were chosen based on the Resistivity of the soils to determine the infiltration rate capacity in each formation. The study utilized a double ring infiltrometer for the experimental analysis, and the infiltration rates were measured at intervals of 1, 2, 5, 10 and 20 minutes up to 123 minutes to assess the potential for soil structure restoration and the efficiency of the Minor Irrigation tanks. The results of this study could provide valuable insights into improving the efficiency of Minor Irrigation tanks and optimizing irrigation practices in the region

Estimating soil water content in a thorny forest ecosystem by time‐lapse electrical resistivity tomography (ERT) and HYDRUS 2D/3D simulations

AbstractDetermination of soil volumetric water content in forest ecosystems is particularly challenging due to deep rooting systems and unknown soil vertical and spatial heterogeneity. This research aims to test two undisturbed methods, electrical resistivity tomography (ERT) and HYDRUS 2D/3D, for 2D determination in a thorny forest ecosystem. The experiment consisted of infiltrating 10 L of water lasting 60 min. During infiltration, ERT measured apparent resistivity by time‐lapse measurements, and was measured with an FDR probe (EnviroSCAN) at 33, 63, 83, 97, and 163 cm depth close to the infiltration site. At the end of infiltration, a soil pit was dug, and 100 measurements of were performed with a TDR in a 10 × 10 cm regular grid. Archie law transformed soil resistivity (ERT) into using manual calibration, verified by an independent dataset. The 2D profile obtained by ERT was qualitatively compared with the HYDRUS 2D/3D one. HYDRUS 2D/3D was parametrized with calibrated parameters obtained with HYDRUS 1D using 106 days of obtained with EnviroSCAN. The results of HYDRUS 1D calibration and verification were satisfactory, with RMSE and Nash‐Sutcliffe coefficients ranging from 0.021 to 0.034 cm3 cm−3 and 0.11 to 0.77, respectively. The forward HYDRUS 2D/3D simulation disagrees with EnviroSCAN data for 33 cm depth. However, it follows the trend with near to zero variation of water content at 63 cm depth. Water content determination by ERT was satisfactory with RMSE for calibration and verification of 0.017 and 0.021 cm3 cm−3. HYDRUS 2D/3D and ERT comparisons were not equal, with a shallower wetting front by ERT and a deeper one for HYDRUS. Still, both wetting fronts agree with the wetting depth estimated by EnviroSCAN. We conclude that both methods are an alternative for determination in heterogeneous and deep soils of forest ecosystems.

Electrical Resistivity Tomography (ERT) Monitoring of Groundwater Flow Condition Surround Deep Excavation in Slope Area

Indonesia is a country with lots of mountain and hills, conducting deep excavation around slope areas will affect the groundwater. Deep excavation will change the groundwater table and hydrogeological condition. In order to monitoring the groundwater flow from the deep excavation in slope area, Electrical Resistivity Tomography used to monitoring the area surround the deep excavation project. The resistivity distribution in the area can be determined by knowing the condition of the soil around the deep excavation project through ERT (Electrical Resistivity Tomography). By utilizing passive ERT, vital parameters, such as porosity and volumetric water content, can be estimated, enabling the calculation of water saturation maps from inverted resistivity values. The resistivity conditions of the soil are continuously monitored, leading to the identification of patterns in soil resistivity movement, and the detection of potential instabilities at the boundaries between areas with varying water saturation levels.

Geoelectric Monitoring of Earthen Hydraulic Structure State by Resistivity and Induced Polarization Methods: Mine Water Settling Pond Dam Case Study

In earth dams, a permanent filtration of water leads to washing out of sand-clay fraction and to a formation of soil decompression sites, which pose a danger to embankment integrity. Condition monitoring of earth hydraulic structures can be executed by geophysical methods. The article presents the results of geoelectric monitoring conducted on the dam of settling pond of mine water with high metal content. The investigations were carried out by vertical electrical soundings, including electrotomography, and by methods of induced polarization in time and frequency domains. According to the results of the electrical soundings, places of reduced soil resistivity in the dam were identified, associated with infiltration of precipitations and of water from the pond. Geoelectric monitoring showed changes of the soils resistivity in different years, depending on hydrological conditions. Induced polarization methods are sensitive to material composition of soils, such as clayiness and presence of electronically conductive minerals. It is determined that the highest content of clay is in the upper and middle parts of the embankment. In eastern part of the dam, intensive polarizability of the medium was detected. It can be caused by filtration of water, contaminated with metals, through the embankment and sedimentary rocks. Thus, by resistivity measurements, it is possible to identify areas of intensive filtration in the dam body, and induced polarization measurements make it possible to determine clay content in the soil and possible pathways of contamination through the dam, which is of great importance for studying the environmental situation of region.

Agrivoltaic approach in improving soil resistivity in large scale solar farms for energy sustainability

Recently, approaches have been established to improve the grounding system performance, especially with the increasing numbers of large-scale solar (LSS) PV farms. Soil resistivity is one of the contributing factors to the inefficiency of power generation as it induces high impedance on electricity flow from the source to highly sensitive PV equipment and devices such as inverters. Some critical issues on nutrient leaching derived from ammonium sulphate fertilizer direct to ground soil are the focal point of this work with the fact that soil resistivity value is inversely proportional to increasing soil salt content. Therefore, a low grounding system could be obtained with a high Electrical Conductivity (EC) and high soil moisture content. In this work, a conceptual setup for an agrivoltaic condition with 500 units of herbal crops has been cultivated directly underneath 1 PV string in Puchong Solar Farm, Selangor, Malaysia. The amount of salt or nutrient under this condition was measured leaching approximately 40 mL per polybag as means of ground treatment to improve soil resistivity value, thus indirectly reducing the risk of electrical damage. The agrivoltaic approach has shown that it can improve the performance of a grounding system in an LSS PV farm with a significant reduction of 4.45 Ω earth resistance on average.

Study on stray current corrosion of buried metal in layered soil

In order to study the effect of layered soil structure on the stray current corrosion of buried metal in urban rail transit, a micro experimental platform for stray current corrosion is established. The research results are obtained by observing the corrosion morphology of buried metal, weighing the mass loss and calculating the corrosion rate. Firstly, the magnitude of stray current in layered soil structure is measured according to the FEM experimental model. Then, with a stray current as the experimental group and without a stray current as the control group studying the effects of the burial depth of metal, soil resistivity and layered soil structure on corrosion respectively. The experimental results show that the degree of stray current corrosion on buried metal in the layered soil structure will be slowed down comparing with the single-layer uniform soil structure, and the degree of stray current corrosion on buried metal will be decreased with the increasing of soil resistivity. Stray current corrosion is mainly concentrated in the anode region of buried metal, and the stray current corrosion of buried metal will be exacerbated with the stray current. In the same soil environment, the closer the buried metal is to the rail, the more serious the corrosion is. Finally, a multiphysics simulation model corresponding to the experiment is established using COMSOL simulation software. After comparison and verification, the simulation results are basically consistent with the experimental results, which prove the accuracy of the experimental results. A theoretical basis for the protection and design of stray current corrosion of buried metal can be provided by the research results.

Failure Analysis of Galvanized Iron Pipe at Perumda Tirta Kanjuruhan

The most commonly used type of water pipe is iron pipe or commonly called Galvanized Iron pipe. The disadvantage of GI pipe is that it rusts easily. So it can result in degradation, decreased efficiency and construction, poor water quality, and higher maintenance costs. Water channeled through rusty pipes will pollute the water and adversely affect the health of those who consume it. This study aims to determine the factors causing failures of GI pipe in the distribution pipeline that have failed due to corrosion. The tested pipes is 1/2"ᴓ sized, 5-year-old corroded pipe whose distribution uses a gravity system and a pumping system. To support this analysis, operational data on fluid and environmental conditions around the pipeline are needed, observations on macro and micro structures, and hardness testing. The corrosion rate is calculated through the thickness loss method and the corrosion rate in the gravity system is 0.153 mm / year that higher than pipe in pumping system. Microstructure observations support the characterization of the material that this pipe is a mild steel, where this type of steel has a high Fe content so it is vulnerable to corrosion attacks. Rockwell hardness testing showed that the corrosion rate is directly proportional to the hardness value of the pipeline. The results of the analysis show that the environment around the pipe which has low soil resistivity and high humidity levels is the main factor in the occurrence of uniform corrosion of the pipe. The selection of inappropriate materials is also supportive as the cause of corrosion occurring.

A method for grounding resistance calculation of vertical electrode

In this paper, a mathematical model on the grounding resistance of vertical electrode is proposed. The proposed mathematical model is modeled with consideration of the effects of parameters such as the length and diameter of vertical electrode, the soil resistivity and the embedding depth. This mathematical model can be applied effectively to the design of grounding system using vertical electrode in harmonious soil with the resistivity values less than 900Ω∙m. The accuracy of proposed model is proved by the simulation analysis and measurement examination of the electric field in this paper.

Effect of Organic Matter Components on the Mechanical Properties of Cemented Soil.

The organic matter in soft clay tends to affect the properties of cement-stabilized soil. The influence degree of different organic matter varies. In this paper, the influence weights and mechanism of the main organic matter components fulvic acid and humic acid on the mechanical properties of cemented soil were investigated. Impacts of FA/HA (fulvic acid/humic acid) values and curing time on the unconfined compressive strength, deformation characteristics, and microstructure of cemented soil were explored through the unconfined compressive strength test and electrical resistivity test. The results show that with the increase of FA/HA, the unconfined compressive strength of cemented soil gradually decreased and the plastic properties enhanced. The increase in curing time changed the stress-strain relationship of cemented soil, and some specimens showed brittle damage. The initial resistivity and structural property parameters of cemented soil gradually decreased with the increasing FA/HA value and increased with the increase of curing time. It revealed the influence law of FA/HA and curing time change on the microstructure of cemented soil. Based on the experimental results, the quantitative relationship equations between FA/HA and curing time and unconfined compressive strength, failure strain, deformation modulus, and resistivity were established.

Design and Validation of Plate Earthing System for Equipment Earthing

Earthing system is an essential part of electrical installation as it helps in eliminating electrical shock hazards and also provide zero voltage reference point for the equipment. Design of an earthing system involves, measurement of soil resistivity of the proposed site for the electrode system installation & determining the conductor type & required number of earth electrodes in order to achieve earth resistance value. This paper describes the methodology followed in design and validation of a plate electrode earthing system for the equipment earthing in a new test laboratory, which had an earth resistance requirement of less than 1 Ohm as mandated by the equipment supplier. This will be helpful for personnel involved in the design of earthing system.

Influence of Compaction on Electrical Resistivity Characteristics of Fine-grained Soil East of Baghdad City, Iraq

In geotechnical practice, there is a continuous demand for an efficient method for measuring the soil moisture content and dry unit weight of compacted soils used in a wide range of earthwork constructions. The Electrical Resistivity method has increasingly been used for rapid and non-invasive assessment of some geotechnical properties. This study aims to evaluate the influence of Moisture Content (MC), Dry Unit Weight (DUW), and Compaction Energy (E) on the Electrical Resistivity (ER) of soil collected from the east of Baghdad City, Iraq. To achieve this goal, soil specimens were compacted to various MC and DUW found in geotechnical practice using different E levels. The ER of prepared specimens was measured using the two electrodes method and compared with various geotechnical parameters related to the compaction process. The results showed that the employed MC, DUW, and E levels influenced the ER. The higher the MC, DUW, and E, the lower the ER. However, the ER was more sensitive to these variables for specimens compacted dry of the optimum. Furthermore, the ER was correlated very well with Volumetric Moisture Content ϴ and Degree of Saturation Sr of soil, with a high correlation coefficient (R2 >94%) and very low p-values, which indicated that these correlations were statistically significant. The current findings indicate the usefulness of the ER method for predicting these parameters. Therefore, using the ER method as a rapid and cost-effective technique for the preliminary evaluation of soil compaction variables in earthwork constructions is recommended. However, the current laboratory findings must be confirmed on different soil types.

Research on the Principle of Anisotropy of Soil Conductivity

Soil conductivity characteristics are the main factors affecting the safety of power system grounding engineering, while the complex distribution of soil resistivity and its anisotropy often cause deviations in the evaluation of the actual grounding. This paper establishes the anisotropy model of soil resistance based on a microscopic perspective, improves the discrimination method of resistance anisotropy, and proposes the conjecture that the variation of resistivity anisotropy is caused by the difference of conductive medium connectivity in different directions. In this paper, the probability distribution of resistivity and the resistance anisotropy ratio are found to be distorted in specific water content intervals, and the trend of the distortion rate is consistent with it, combined with the critical conditions of sudden changes in soil resistivity. Moreover, the correctness of the conjecture is verified in this research. It is also found that there is more than a single conductive mutation interval in the soil, and one of them is at low water content in the high porosity model due to differences in the connectivity of the soil skeleton in all directions. This method can be applied to other studies of soil anisotropy, such as percolation, by changing the conditions and parameters.

Adaptation of multipurpose tractors to row spaces of cotton crops

In the Republic of Uzbekistan, cotton cultivation is carried out on row spacings of 60; 76 and 90 cm. The machine-tractor parks of cotton-growing farms are equipped with agricultural machines designed for these inter-row spacings and they are aggregated by tractors with gauges designed for them. Such a variety of tractor gauges creates the problem of mismatch between the gauge and row spacing when moving from one row spacing to another, increases the variety of spare parts and narrows the scope of their use only within one type of row spacing. The discrepancy between the gauge of serial universal row-crop tractors and the cultivated row spacing leads to damage to the plant and compaction of the soil in the area where its root system is located. Overconsolidation of the soil by more than 1.1 g/cm3 leads to a slowdown in plant growth and development, an increase in soil resistivity during subsequent tillage operations and, most importantly, a decrease in crop yield. Studies have established that, despite the variety of designs of known devices used to adjust the track, they change the track stepwise and in an insufficient range, as a result of which the tractor does not fit into the row spacing. To eliminate the shortcomings of the known methods for adjusting the track, a device has been developed for adapting the tractor running system to work on different row spacings. The developed device allows, without the use of attachments or interchangeable axle shafts and their casings, to accurately adapt the tractor’s running system to the aisle of crops cultivated by it, thereby eliminating the existing shortcomings of serial universal row-cultivator tractors. The article provides a description of the proposed technical solution and the method of its application.

Analysis of overvoltages across line insulator strings considering the ground-wire and phase conductors corona

This paper assesses the influence of corona effect on the overvoltages developed across the insulator strings of overhead transmission lines due to lightning. The influence of corona is investigated considering lightning strikes to the tower top and shielding wires at midspan. A large range of soil resistivity and lightning currents peaks are evaluated in the analysis, and the stress across the insulator strings is evaluated applying the integration method. Simulations are carried out in the Alternative Transient Program (ATP/EMTP), wherein the corona effect is represented through the accurate Suliciu corona model, which was implemented using the MODELS interface and combined with J. Marti line model. Furthermore, it was also represented the wideband behavior of tower grounding system. Results showed that corona effect has a minor influence in the overvoltages across the insulator string for strikes to the tower top. However, it strongly influences the overvoltages across line insulators ensuing from a lightning strike to the shielding wire at the midspan, leading to a decrease in the peak value of the lightning current that causes line flashover.

Response of High Swelling Montmorillonite Clays with Aqueous Polymer

Expansive clays containing mineral montmorillonite exhibit swelling and shrinkage due to variations in the moisture content, leading to significant distresses. There has been a growing interest in chemical and polymer additives treated for high swelling montmorillonite clays in recent years. However, limited attention has been paid to the effect of polyacrylamide on the soil’s swelling behavior. Moreover, nontraditional methods of the soil treatment are applied for the rapid stabilization of soil. In this article, polyacrylamide polymer is used as an additive to expansive clays to control the swelling phenomenon. Three different percentages—2.5%, 5%, and 7.5%—of polymer are blended with oven-dried soil to determine Atterberg limits, compaction features, and swelling characteristics. Additionally, electrical impedance measurement is conducted on treated soil samples with different moisture contents. The electrical resistance of soils and polymer-treated soils is measured based on the electrical resistivity correlation of soils. Tests results for soils stabilized with polyacrylamide show that swelling is significantly reduced with increasing the additive content. Moreover, the addition of polymer improves resistivity of soil. Aqueous polyacrylamide can be utilized as an effective stabilization additive to enhance properties of expansive clays.

Full-wave electromagnetic analysis of lightning strikes to wind farm connected to medium-voltage distribution lines

This paper studies the voltages developed on a wind turbine (WT) and a medium-voltage distribution line (MVDL) connected to a wind farm subjected to lightning strikes and located on frequency-dependent (FD) soils. The ground potential rise (GPR), voltages at the blade tip and on phase conductors of the MVDL are calculated using the full-wave electromagnetic software XGSLab® employing the rigorous Partial Element Equivalent Circuit (PEEC) method. The wind farm comprises four wind turbines with interconnected grounding systems using cables buried in resistivity soils of 1,000 and 5,000 Ω m. The voltages are computed for the first positive impulse (FPI) of 100-kA 10/350μs and for the subsequent negative impulse (SNI) of 50-kA, 1/200μs. Results have shown that voltage peaks increase notably as the soil resistivity increases. When the WTs are assumed, oscillations in the GPR waveforms for the SNI occur due to the multiple reflections between the blade and the turbine’s base. However, the voltages for the FPI present smooth time-domain responses. Furthermore, the overvoltages developed at the MVDL are significantly dependent on the soil resistivity and lightning current waveform.

Influence of a shield wire flashover on the indirect lightning performance assessment of distribution lines

This paper presents a new aspect of shield wire (SW) modeling for assessing the indirect lightning performance of overhead medium-voltage distribution lines: a flashover (FO) between an SW and the reinforcing bars of a distribution pole or a crossarm (SWFO). In general, an SW is periodically grounded approximately every four to ten poles and not grounded at the other poles. However, owing to lightning-induced overvoltages, the voltage difference between the SW and the distribution pole may even exceed 100 kV, and the SWFO can occur. In this paper, we evaluate the effect of the SWFO on the number of FO occurrences of phase-conductor insulators by the Monte Carlo method using a 2D finite-difference time-domain-based indirect lightning surge analysis program. The effect of the SWFO is more significant in lines with high soil resistivity (a soil resistivity of 1000 Ωm was assumed) regardless of the installation of surge arresters: the total number of FO occurrences markedly differs by up to 50% between cases in which the SWFO is considered and not considered. The analysis presented in this paper will assist the formulation of lightning protection measures particularly, in regions with high-resistivity soils.

Assessment of the transmission line theory in the modeling of multiconductor underground cable systems for transient analysis using a full-wave FDTD method

In this paper, a rigorous and independent validation of two different approaches for calculating the ground-return impedance and admittance of multiconductor underground cable systems using the transmission line theory is carried out. Furthermore, analyses are performed to evaluate the accuracy of a closed-form approximation for the calculation of the ground-return admittance of underground cable systems. The validations are based on the full-wave finite-difference time-domain (FDTD) method and consider the calculation of transients on flat and trefoil underground cable arrangements for different excitation types. Short cable lengths of 50 m and 100 m and soil resistivities of up to 1000 Ωm are considered. The results demonstrate the validity of the transmission line theory for the calculation of fast transients (with risetimes as low as 0.2 µs) on underground cables provided the ground-return parameters are rigorously determined, with the advantage of presenting much greater efficiency and easiness to implement in electromagnetic transient simulators compared to the full-wave FDTD method. Lastly, it is shown that the ground-return admittance approximation, despite its simplicity, leads to results comparable to those obtained through more complete formulations for the calculation of transients in underground cables, but more efficiently and without significant loss of accuracy.