Soil Resistivity Research Articles

Earthing System Analysis for Steel Tower Carrying 33kV Line

This study examines the critical analysis of earthing systems connected to steel towers that carry 33 kV power lines. Ensuring the safety and dependability of power transmission infrastructure becomes crucial in light of the growing demand for energy. By utilizing sophisticated computational methodologies and simulation approaches, this research carefully investigates how well the earthing system performs in various operational circumstances and fault scenarios. A thorough modeling technique is used in the analysis, which considers a number of variables including fault currents, tower design, soil resistivity, and grounding electrode configurations. In order to give a comprehensive understanding of the behavior of the system and its consequences for operational reliability, the study simulates many situations, including normal operation and fault occurrences. By using sophisticated numerical simulations and sensitivity analysis, the research pinpoints important factors affecting the earthing system's efficiency and suggests creative optimization techniques. These optimization techniques could involve changing the location of the grounding electrode, improving the materials used in the conductor, or putting additional safety precautions in place. The researcher's conclusions have important ramifications for the engineering community since they provide practical advice on how to strengthen the security and robustness of power transmission networks. The study adds to the continuous efforts to improve the efficiency and dependability of electrical grids by addressing potential weaknesses in the architecture of the earthing system. This thorough study advances the field of earthing system engineering by offering a solid platform for next studies and real-world implementations. Through this work, we can better understand the dynamics of earthing systems and optimization methodologies, which will help build more resilient and sustainable power transmission infrastructure that can adapt to society's changing energy needs.

Estimation of Standard Penetration Test (SPT) Depth Testing Plan on Geoelectrical Resistivity Data Correlation (Ωm)

Abstract— Analysis of soil bearing capacity in receiving loads is an important step in the construction of building structures, namely as a basis for planning types, materials, material quality, and foundation dimensions. This study aims to analyze the minimum resistivity (Ωm) of soil or rock material that is correlated with the Standard Penetration Test (N-SPT) value of ≥ 50. This is done as the basis for estimating the depth of drilling in the Standard Penetration Test (SPT) test. This study applies a geolytic approach to study soil and rock specifications. The research data includes descriptions of soil types, depth and thickness of each soil layer, material resistivity which is interpreted as soil density, minerals, to the presence of water content in the soil layers. The results of the data correlation analysis show that the higher the resistivity value of the soil or rock material (Ωm), the greater the number of collisions (N). The minimum resistivity value of soil material is more than (>) 121.27 Ωm obtained from the number of (N) collisions of the Standard Penetration Test (N-SPT) of more than (≥) 50. Thus, further estimation of the drilling depth can be carried out. The depth of drilling for each location varies, depending on the carrying capacity of the soil, which ultimately determines the amount of drilling costs.

Assessment of the accuracy of the modal-domain line models with real and frequency-independent transformation matrix for electromagnetic transient simulation in lines with underbuilt cables

This paper investigates the potential inaccuracies associated with using a modal-domain model featuring a real and frequency-independent transformation matrix in simulating electromagnetic transients on power overhead lines equipped with underbuilt wires. Three transmission line configurations are examined: one without underbuilt wires, one with a single underbuilt wire, and another with two underbuilt wires. Comparisons between the simulated voltages computed using the modal-domain approach and a more accurate phase-domain model as a reference reveal that the modal-domain approach leads to inaccuracies in the simulated voltages. These inaccuracies intensify with an increase in the number of underbuilt wires and the soil resistivity. Differences of up to approximately 24 % in the peak values of the simulated voltages were observed, considering the transmission line geometry analyzed in this study. Based on these findings, it is recommended that for simulating transients in overhead lines with installed underbuilt wires, phase-domain models, such as the Universal Line Model, should be employed.

Lightning-induced voltages on low-voltage distribution lines

Special attention has been drawn to transients in low-voltage systems in recent years. As the surge withstand capabilities of low-voltage networks are much lower than those of medium-voltage lines, they are more susceptible to lightning-caused disturbances. One of the primary sources of overvoltages is related to indirect lightning strokes. Such overvoltages are highly dependent on the soil characteristics and generally tend to increase with the soil resistivity. Considering realistic conditions, this paper discusses the effects of different parameters on the phase-to-ground and phase-to-neutral lightning-induced voltages on the low-voltage side of a typical distribution transformer. In the case of high-resistivity soils or high ground resistance values, phase-to-ground voltages induced by indirect strokes can reach several tens of kilovolts. Phase-to-neutral voltages higher than 5 kV may be common if surge protective devices are not applied.

Field tests of square and double exponential pulses for transient resistivity measurements using Wenner arrays and hemispheres

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 ρo.

Determining the influence of soil layers on apparent soil resistivity through small-scale laboratory experiments

ABSTRACT Electrical resistivity (ER) method, non-destructive approach determining subsurface anomalies by leveraging electrical properties. In-situ ER is popular owing to its quick, reliable and continuous subsurface data, although heterogeneity across horizontal and vertical orientation is less explored. In this regard, present study tends to understand this effect by carrying out small-scale laboratory ER tests focusing on how varying vertical soil layer positions impact resistivity. Two distinct soil types with varying resistivity were arranged in both perpendicular and parallel direction to current flow, where low and high resistive layers were placed adjacent to one another. Results derived from study indicated that placement of low resistive soil before high resistive one leads to 37.58 % reduction in resistivity. Furthermore, parallel alignment resulted in 9.89 % decrease compared to perpendicular layering. Thus, these findings tends to highlight significance of layering in influencing resistivity values and underscoring the complexity of electrical resistivity testing.

Prediction of external corrosion rate for buried oil and gas pipelines: A novel deep learning method with DNN and attention mechanism

Buried pipelines is easily subjected to external corrosion affected by complex underground environment, such as soil resistivity, pH, dissolved ion concentration, water content and coatings condition. Therefore, external corrosion rate prediction is essential to ensure pipelines intrinsic safety. Generally numerous researches focused on mathematical models and degradation analysis are limited to considering comprehensive corrosion factors. In this work, a novel proposed deep learning method involves a deep neural network (DNN) and attention mechanism which has good robust generalization ability. DNN was used to predict external corrosion rate of buried pipelines with extracting corrosion characteristics data, and attention mechanism is carried on weighting operations of corrosion factors furtherly. The results show that main controlling factors are pipeline age and soil bulk density, sulfate ion concentration and redox potential have less effect by analyzing external corrosion factors dataset, and data reduction and standardization of DNN-attention mechanism model are carried out. The external corrosion rate value predicted by the DNN-attention mechanism model is the closest prediction with the real truth, which the evaluation index root mean square error (RMSE) is 0.0064, and prediction accuracy is 91.91 % compared with convolutional neural network (CNN), CNN-residual, DNN. It proves that it is reasonable to predict pipeline external corrosion rate using DNN-attention mechanism based on publicly pipeline corrosion dataset.

Electromagnetic Impact of Overhead High-Voltage Lines during Power Transmission on Buried Signaling Cables of the Traffic Control Systems in Modernized Railway Lines

The railway transport system is a key factor supporting industrialization in all aspects of human activity. However, in order not to lose its importance, it must meet the challenge of modern civilization. The safety, reliability, and efficiency of railway transport, to a large degree, depend on using highly integrated electronics, which are very sensitive to various disturbances generated in the electric traction system and train or coming from the environment. One of the sources of electromagnetic disturbances are high-voltage (HV) power lines running close to the railway infrastructure. The purpose was to assess the electromagnetic impact of overhead HV transmission lines on buried signaling cables of the railway traffic control system crossbreeding with them. The levels of voltage induced in the cable under steady state and the earth fault in the HV line at various soil resistivity were estimated. A software tool based on a hybrid numerical method that combines circuit theory and electromagnetic field theory was used for computations. It was found that very high voltages may be induced in the signaling cables during earth faults in the HV lines, which may lead to serious interference or damage to the equipment. The results provide useful knowledge for implementing modern railway traffic control systems and protection measures.

Unraveling mechanisms and failures of stray current corrosion in urban Subway adjacent pipeline networks through statistical insights and 3D simulation

The escalating expansion of urban subway systems in recent years has accentuated the issue of stray current corrosion within pipeline networks, emerging as a critical concern for urban safety. This paper delves into the intricate interplay between these phenomena, employing data-driven statistical analyses to elucidate the coupling characteristics between subway lines and the occurrence of failures in adjacent buried pipelines. An advanced three-dimensional finite element model was developed for stray current corrosion in pipelines, seamlessly integrating empirical data and physics-based modeling, which is to uncover the spatial nuances and multifaceted impacts on subway pipeline corrosion from both macro and micro perspectives under varying influencing factors. The study unveils a pronounced geographical and functional affinity between urban subway networks and metallic pipeline networks. The coupling attributes between subway systems and pipelines, such as distance, angle, and pipeline-specific characteristics including material and age, assume pivotal roles. The results further emphasize the hierarchical order of influence, with stray current intensity holding the greatest sway, followed by the distance between subway and pipelines, the angle between them, and soil resistivity. This paper offers a comprehensive investigation of the interrelationships and influential factors between subway systems and adjacent pipelines. It contributes to the mitigation and management of stray current corrosion in pipelines induced by nearby rail transit, thereby enhancing the resilience of both subway and pipeline networks within urban areas.

Combined 2D- and 3D ERT monitoring as a geophysical tool for investigating spatial and temporal soil moisture fluctuations in a pine-beech forest

As climate change continues, forests are increasingly suffering from drought stress, which is leading to widespread forest dieback, but also to increased mortality of individual trees. In this regard, the impact of small-scale differences in water availability on individual trees has not yet been sufficiently studied to determine possible responses of different tree species to future droughts. Since conventional soil moisture monitoring and sampling methods only consider single points or small volumes, Electrical Resistivity Tomography (ERT) is becoming increasingly important to cover a larger survey area and to detect small-scale heterogeneities with regard to soil properties and soil moisture.The current study describes the application of a combined two- and three-dimensional geoelectrical monitoring approach with daily measurements over two years (May 2021 – April 2023) in a forest ecosystem in Lower Franconia (northwestern Bavaria, Germany), which is strongly affected by climate change. Soil water content, soil matric potential, throughfall, and stem flow are also measured at the forest site as well as precipitation at an adjacent forest clearing.The seasonally (long-term) and precipitation-driven (short-term) temporal change of soil resistivity is correlated strongly with the measured soil water content and matric potential. The applied 3D-ERT approach also allowed a first three-dimensional monitoring of the subsurface below a European beech located in the middle of the measuring grid with a daily resolution. The corresponding results also provide first indications that besides soil moisture changes also chemical processes in the subsurface may influence temporal resistivity changes in the soil of forest sites.The results of this study show that daily 3D-ERT is very suitable for investigating small-scale as well as short- and long-term variations in soil moisture, which is becoming increasingly important for understanding the causal relationships considering tree mortality and the subsurface.

Optimisation of the Distribution System Reliability with Shielding and Grounding Design Under Various Soil Resistivities

Lightning strikes can cause equipment damage and power outages, so the distribution system's reliability in withstanding lightning strikes is crucial. This research paper presents a model that aims to optimise the configuration of a lightning protection system (LPS) in the power distribution system and minimise the System Average Interruption Frequency Index (SAIFI), a measure of reliability, and the associated cost investment. The proposed lightning electromagnetic transient model considers LPS factors such as feeder shielding, grounding design, and soil types, which affect critical current, flashover rates, SAIFI, and cost. A metaheuristic algorithm, PSOGSA, is used to obtain the optimal solution. The paper's main contribution is exploring grounding schemes and soil resistivity's impact on SAIFI. Using 4 grounding rods arranged in a straight line under the soil with 10 Ωm resistivity reduces grounding resistance and decreases SAIFI from 3.783 int./yr (no LPS) to 0.146 int./yr. Unshielded LPS has no significant effect on critical current for soil resistivity. Four test cases with different cost investments are considered, and numerical simulations are conducted. Shielded LPSs are more sensitive to grounding topologies and soil resistivities, wherein higher investment, with 10 Ωm soil resistivity, SAIFI decreases the most by 73.34%. In contrast, SAIFIs for 1 kΩm and 10 kΩm soil resistivities show minor decreases compared to SAIFIs with no LPS. The study emphasises the importance of considering soil resistivity and investment cost when selecting the optimal LPS configuration for distribution systems, as well as the significance of LPS selection in reducing interruptions to customers.

Electrical Resistivity Behavior of Saline Soil under Low-Temperature Conditions

Freeze-thaw cycling of frozen soils is known to be the cause of various engineering failures of infrastructure in cold regions. Researchers found that electrical resistivity methods outperform traditional ground surveying methods in frozen soils for their greater convenience and cost-effectiveness. However, detailed investigation into the relationship between the electrical resistivity of soil and a variety of soil properties is still needed. In this study, a series of laboratory experiments using the Wenner method were conducted to determine the relationship between soil electrical resistivity and soil geotechnical properties such as initial water content and pore fluid concentration under freeze-thaw conditions. Cylindrical soil samples undergo artificial freeze-thaw cycles to a temperature as low as −70°C, and electrical resistivity and temperature values are recorded simultaneously. Measurement results are summarized for curve fitting, and a statistical model showing relationship between electrical resistivity and temperature during freezing and thawing was given. Above freezing point, the log of electrical resistivity had a linear relationship with temperature. Below freezing point and above −15°C, the log of electrical resistivity had a square root relationship with temperature. Different trends in electrical resistivity change in extremely low-temperature regions (from −15°C to −70°C) are also discussed. In extremely low-temperature regions, the electrical resistivity of frozen soils did not monotonously increase with lower temperature, which may be because of increasing salt concentration in the unfrozen water phase. The findings of this study are expected to bring more insights to frozen soil structure, and assist in geophysical surveying in cold regions and construction methods utilizing ground freezing.

Characterization of subsurface geology and hydrogeology in Kribi -Cameroon using electrical resistivity soundings and 3D-Implicit modelling: Baseline for groundwater resource management

This scientific article aims to characterize the geology and hydrogeology of Kribi, Cameroon for the purposes of water resources management, infrastructure development, and environmental protection. The specific objectives include mapping the subsurface electrical resistivity structure, identifying groundwater potential zones, and constructing a hydrogeological model for groundwater modelling. The study employed the Schlumberger method to map the electrical resistivity structure of the 3D subsurface and utilized 3D implicit modelling techniques to delineate groundwater potential zones. The study revealed that Kribi exhibits a highly complex geology, characterized by three-layered electrical resistivity models, typical of sedimentary and metamorphic formations. The major lithologies identified include laterite, clay, sand, quartz, and granite. The region encompasses areas with low water potential and brackish zones alongside high groundwater production areas. The study established the presence of aquifers within Kribi, with the unconfined aquifer found at depths ranging from 2 m to 13 m, and the confined aquifer extending from 14 m to 40 m. The aquifers are notably thick and productive, indicating substantial groundwater resources. Static groundwater volumes were estimated at 50,179,381 m3 and 317,118,946 m3 for the unconfined and confined aquifers respectively. Despite this potential, water resources management in the area is non-existent. The study recommends the implementation of Integrated Water Resources Management (IWRM) to improve water resource management, with a primary focus on groundwater modelling. The northern and southern regions of Kribi exhibit high permeability, which is advantageous for groundwater recharge and storage projects but also poses challenges for environmental remediation efforts. Consequently, safeguarding the delineated area for groundwater provision is of utmost importance.

Geospatial analysis of soil resistivity and hydro-parameters for groundwater assessment

Groundwater is a precious resource for irrigating the crops in developing countries. This research was governed in Faisalabad District of Pakistan to assess the groundwater strata using GIS cum geoelectric resistivity method approach. The IX1D computer model was calibrated with root mean square error (up-to 5%), to obtain true soil layers’ resistivities and thicknesses model for each VES point based on apparent resistivity data collected by ABEM SAS 4000 Terrameter using the most common Schlumberger electrode array setting. Knowledge of geo-hydraulic parameters (hydraulic conductivity, transmissivity, and porosity) aids in identifying the quality and potential of groundwater repositories, estimated based on modeling results (soil layers resistivities and thicknesses). Most common interpolation (inverse distance weighted) method in ArcGIS Pro was used for mapping the soil aquifer layers resistivities/thicknesses and geo-hydraulic parameters. Transmissivity, Porosity, and hydraulic conductivity values ranged from 365.46 to 1888.503 m2/day, 31.84 to 39.72% and 4.05 to 15.27 m/day for all surveys, respectively. Based on these results, aquifer layers with thicknesses 30 to 103.5 m, were distinguished as comprised of saline to low marginal quality (fine sand and clay formation), marginal to fresh quality (fine sand and gravel formation) and fresh quality groundwater (coarse sand and gravel formation).Graphical

Geological, geophysical, and geotechnical approaches on the slip surface investigation on Cisumdawu Highway, West Java, Indonesia

This study used geological, geophysical, and geotechnical methods to investigate the causes of landslides in a newly established Cileunyi Sumedang Dawuan (Cisumdawu) Highway, Sumedang Regency, West Java Province. A combination of geological field observation, subsurface geoelectric resistivity-based survey, and borehole drilling were applied to obtain the subsurface data of a research area. A total of 10 boreholes were drilled to collect geoengineering data, including the soil material and N-SPT value for validation purposes. The soil hardness and resistivity were measured and compared to establish the relationship between resistivity and engineering properties. The result revealed that percolating water zone in the permeable loose soil was located above the impermeable layer, estimated as a slip surface. The analysed subsurface measurement and borehole data showed that the depth of the slip surface is between 26-27m. The study is important to determine the mitigation steps for the highway slope stability construction.

Identification of Pesticide-Saturated Soil Using Near-Surface Geophysics Method

Harmful substances deposited in the soil can disrupt soil functions, leading to environmental pollution and harm. Pesticides are one example of these harmful substances. Absorption of pesticides into the soil can lead to infertility and negatively impact overall soil health. Therefore, a study was conducted to identify pesticide-saturated soil near the surface and map the soil health conditions around Situ Cisanti. The research utilized geoelectric methods and collected soil and water samples from the inlet (a) and outlet (b) areas of Situ Cisanti. After conducting measurements around Situ Cisanti, the data collected include soil resistivity, ranging from 0.483 to 2.04 Ωm (a) and 658 to 2787 Ωm (b). Soil pH levels were 8.9 - 9.0 (a) and 8.9 (b). Soil Electrical Conductivity (EC) and Total Dissolved Solids (TDS) measured 250 - 280 μs and 194 - 207 ppm (a), and 240 μs and 178 ppm (b). Water pH was 7.7 (a) and 8.7 - 9.1 (b). Water EC and TDS were 100 μs and 83 ppm (a), and 80 - 180 μs and 65 - 94 ppm (b). The results indicated higher pesticide contamination in the outlet compared to the inlet, signifying potential risks to soil health.

Identification Of Soil Resistivity Distribution In Ekoriparian Leuwi Padjadjaran Area Using 2D Electrical Resistivity Method

Research focused on the identification of soil resistivity distribution at the Ekoriparian Leuwi Padjadjaran area, University of Padjadjaran, Jatinangor, has been conducted using geoelectric resistivity method 2D with dipole - dipole configuration. Three survey lines were measured with the first and second lines being 2 meters long and the third line measuring 6 meters. Electrode spacing was set at 0.2 meters, with 10 electrodes on the first and second lines, and 30 electrodes on the third line. Data processing is done using the Res2Dinv software. The research results indicated that resistivity values in the range of 4.00 Ωm to 20.0 Ωm were interpreted as clay rocks, values from 20 Ωm to 200 Ωm were interpreted as silt rocks, and resistivity values in the range of 256 Ωm to 1024 Ωm were interpreted as sandy clay rocks. Based on the geology of the study area, the soil is a fine-grained soil, namely silt and sandy loam.

Assessment of Impact of Agricultural Land-Use Types on Some Soil Physical and Chemical Properties in Abeokuta, Southwestern Nigeria

Agricultural land-use practices play a pivotal role in shaping the physical and chemical properties of soil, which in turn influence crop productivity, environmental sustainability, and overall ecosystem health. Understanding the impact of different agricultural land-use types on soil properties is crucial for sustainable land management and effective agricultural practices. This study utilized electrical resistivity technique (ERT) and geochemical methods to assess the impact of different land-uses (mineral farms, organic farms, thick plantations, and cattle stations) on soil physicochemical properties. The research aimed to explore the correlation between soil resistivity and fertility, as well as evaluate the influence of specific land-use types on soil characteristics. Four resistivity traverses were conducted, each corresponding to a different land-use type, and soil samples were collected from various depths. Laboratory analysis revealed high clay content in the cattle station, while all land-use types showed high sand content. Available phosphorus was significantly affected by both land-use and soil depth, negatively correlating with electrical conductivity. Exchangeable bases were generally low across all land-use types. The study recommends promoting site-specific, sustainable land management practices within different agricultural land-use systems.

Optimizing Current Injection Technique for Enhancing Resistivity Method

Geo-electrical resistivity methods are widely used in various fields and have significant applications in scientific and practical research. Despite the widespread use of resistivity methods, current injection is a critical step in the process of resistivity methods, and the quality of current injection significantly impacts the accuracy of the resistivity measurements. One primary challenge is optimizing current injection techniques to enhance resistivity methods. The developed current injector model for the resistivity meter instrument enhances performance by increasing the voltage source to 400 Volts, extending measurement coverage. It provides three injection current options, 0.5A, 0.8A, and 1A, for efficient accumulator use, considering electrode distances and estimating earth resistance using Contact Resistance Measurement (CRM) to estimate the earth resistance. CRM mode ensures proper electrode connection before injection, thus improving measurement efficiency. The embedded TTGO LoRa ESP32 SX1276 facilitates wireless communication over 1.5 km, addressing challenges in remote and internet-limited areas. The model demonstrates reliability, validity, and durability in CRM mode and current injection measurement. Regarding reliability, we determine the relative error of the model by carrying out measurements repeatedly. In lab-scale testing, the average Relative Error in CRM mode is 0.65%, and in earth resistance measurement testing, it is 1.58%. These relative errors are below the 2% maximum error applied in the “Supersting”, a commercial resistivity instrument. The model's validity is defined by comparing the model with the measuring instrument; we have absolute error. In lab scale testing, the average Absolute Error in CRM mode is 3.08%, and in earth resistance measurement testing, it is 3.73%. The model's durability is tested by injecting current for a minute. After one minute of current injection, the power resistor component's temperature is stable at 30°C.

Optimizing Current Injection Technique for Enhancing Resistivity Method

Geo-electrical resistivity methods are widely used in various fields and have significant applications in scientific and practical research. Despite the widespread use of resistivity methods, current injection is a critical step in the process of resistivity methods, and the quality of current injection significantly impacts the accuracy of the resistivity measurements. One primary challenge is optimizing current injection techniques to enhance resistivity methods. The developed current injector model for the resistivity meter instrument enhances performance by increasing the voltage source to 400 Volts, extending measurement coverage. It provides three injection current options, 0.5A, 0.8A, and 1A, for efficient accumulator use, considering electrode distances and estimating earth resistance using Contact Resistance Measurement (CRM) to estimate the earth resistance. CRM mode ensures proper electrode connection before injection, thus improving measurement efficiency. The embedded TTGO LoRa ESP32 SX1276 facilitates wireless communication over 1.5 km, addressing challenges in remote and internet-limited areas. The model demonstrates reliability, validity, and durability in CRM mode and current injection measurement. Regarding reliability, we determine the relative error of the model by carrying out measurements repeatedly. In lab-scale testing, the average Relative Error in CRM mode is 0.65%, and in earth resistance measurement testing, it is 1.58%. These relative errors are below the 2% maximum error applied in the “Supersting”, a commercial resistivity instrument. The model's validity is defined by comparing the model with the measuring instrument; we have absolute error. In lab scale testing, the average Absolute Error in CRM mode is 3.08%, and in earth resistance measurement testing, it is 3.73%. The model's durability is tested by injecting current for a minute. After one minute of current injection, the power resistor component's temperature is stable at 30°C.