2D Resistivity Research Articles

Methodology for the Identification of Moisture Content in Tailings Dam Walls Based on Electrical Resistivity Tomography Technique

The design of tailings dams has improved significantly in recent decades due to experience and advances in applied research. However, there are still several environmental and geomechanical uncertainties associated with the response of these structures. Failures on the wall of tailings dams are well documented, where the most common causes are related to the action of water overtopping, slope instability, seepage, and foundation failure. Measuring the humidity or the saturation level at tailings dam walls has become a must do in the recent years. Resistivity monitoring using electrical resistivity tomography (ERT) techniques has proven to be one of the tools that provide good subsurface characterization for internal erosion detection and seepage assessment to evaluate potential environmental risks and the physical stability of tailings dams. Also, the integrated techniques of geotechnical, geophysical, and geochemical data have been used to correlate, coordinate, and improve the characterization. In this research, a procedure to guide us to a new methodology of acquiring and monitoring humidity content is presented, in which 2D electrical resistivity tomography (ERT) profiles are linked to the degree of soil saturation, using moisture sensors installed in a nearby well. The ERT profiles provide a 2D resistivity profile, and the moisture sensors can measure resistivity and volumetric water content (VWC) at a given installation depth. This second measure (VWC), with a defined total porosity, can be combined with Archie’s empirical law to obtain the degree of saturation, allowing the possibility to create remote monitoring suitable for mining operations without excessive laboratory testing.

A New Technique of Grouting to Prevent Water–Sand Mixture Inrush inside the Mine Panel—A Case Study

Water–sand mixture inrush generally poses a significant threat to the safe operation of the quarry of coal mines. Therefore, proactive management initiatives are essential to enhance the impact resulting from mining operations. A novel approach involving grouting into the unconsolidated sand aquifer and the weathered zone was initially executed in the 1010-1 panel of the Wugou coal mine in Anhui Province, China. Considering the hydrogeological conditions of the study area, over 70 thousand tons of cement and fly ash were injected through 42 boreholes. Sampling, laboratory tests, similar materials model simulations, and numerical simulations of the trending and dipping profiles were all employed to elucidate the evolution and characteristics during the progression of the No. 10 coal seam. The outcomes illustrated that the grouting execution had transformed the structure of the porous media, weakened the watery media, and intensified the mechanical strength of the No. 4 aquifer and the weathering zone. This transformation proved beneficial in reducing the heights of the caving zone and water-conductive fracture zone, leaving more coal–rock pillars for safety. Twenty-seven underground detection drill holes and whole-space 3D resistivity exploration were adopted to verify its transformed property of low water content. During the mining process, the height of the caving zone at 19.70 m was measured through inter-hole parallel electrical detection. The pressure of hydraulic supports in the grouted area did not exceed the rated working pressure during mining. All of these findings highlight the significant impact of grouting in this study area. The successive safe mining of the 1010-1 panel demonstrates that grouting can be used to prevent water–sand mixture inrush during mining operations.

The Result of Electrical Resistivity Investigation of Solid Waste Landfill Conducted at Nsukka Municipality Using Electrical Resistivity Measurments

Solid waste landfill management has been a significant issue for Nigerian urban areas and other developing countries across the globe.Similar to most other cities, Nsukka also generates waste on a daily basis, much of which is dumped in poorly designed and positioned dumping sites. The majority of the disposal sites are found on roadsides, at marketplaces, on farms, and in residential neighborhoods, among other places. The road infrastructure and groundwater are under danger, and the beauty of the impacted communities are not spared. Undoubtedly, the unchecked citation of boreholes as the source of potable water in the majority of our rural and urban communities—given that the government doesn't seem to be providing water to the people—has become a significant challenge. An investigation using electrical resistivity method was conducted around a solid waste dumpsite at Nsukka in Nsukka L.G.A of Enugu State, Nigeria with an aim to investigate the level of groundwater contamination and the objectives to determine the subsurface geoelectric layers, depth to water table, lithology delineation and map out the contamination zones. The scope of this study provides an overview of some of the approaches used to assess the aquifer vulnerability and aquifer potential using Vertical Electrical Sounding (Schlumberger array) and 2D resistivity imaging (Wenner array) in different locations around Nsukka municipality dumpsite. Both methods were used for this study in order to provide a geophysical database for exploration of the study area’s groundwater resources and also they are less expensive and less time consuming. VES has proved to be effective in solving groundwater problems in most places in Nigeria (Ezeh and Ugwu, 2010; Ugwu and Ezeh, 2012; Nzemeka et al. [1,2]. Electrical Sounding (VES) and 2D resistivity imaging were carried out with a digital read out resistivity meter (ABEM SAS 1000) to acquire data in the area and were interpreted using the Schlumberger automatic INTERPEX analysis software and the RES2DINV software respectively, which generates model curves using initial layer parameters and display the variations of electrical resistivities respectively. A total of eight (8) sounding and six (6) 2D resistivity imagings were carried out in the area. A contaminant leachate plume was delineated in 2D resistivity sections as low resistivity zones while the VES shows the depth of aquifer. In 2D pseudosections where bluish colours with low resistivities (less than 20.80\(\Omega\)m) with the depth ranging from 1.28m to 17.1m in the Line 1 and 2 are seen as contaminated zones. The rest of the lines are not contaminated because of their high resistivities (greater than 20.80\(\Omega\)m). The result of the electrical resistivity survey also showed 4 - 5 layers geo-electric sections and an AA and AK type sounding curves. The VES result shows that VES 1A, 1B, 2A and 2B which are carried out on line 1 & 2 of the wenner lines showed signs of contamination with low resistivity values less than 20.80\(\Omega\)m complementing the wenner results. The contamination has not yet got to where the aquifer is located on the lines. Since the depth to the aquifer ranges from 30.26m to 155.43m while maximum depth of contamination is 17.1m. It is believed that the leachate has not percolated down to the aquiferous zones as such aquifers are presumed to be free. As such, it is recommended that boreholes around the study area should not be less than 30m deep to avoid exploiting polluted water.

Ingress of municipal solid waste into water resources: an environmental assessment and monitoring tool near dumpsites in Akwa Ibom State, Nigeria

ABSTRACT Municipal solid waste (MSW) dumping sites are only used for trash discarding. Beyond the reek that the dumpsites generate, which defiles the milieu, the primary issue is the spreading of fluid from the landfills. The thrust of this research is to utilize the contiguous data from geophysics and laboratory analysis of groundwater samples to decipher the influence of MSW on aquifer systems in Uyo and Eket Counties. Geo-electrical studies featured vertical electrical sounding (VES) and constant electrode separation techniques to generate 1D and 2D electrical resistivity models. The analyzed field data were integrated with water sample analysis to deduce the influence of leachate on groundwater. The VES curve types conformed to A (7.1%), HK (21.4%), Q (21.4%), and K (50.0%). The created 2D image maps for MSW locations lay bare the fact that leachate dispersal between source and sink obeys the inverse square rule. The heavy ions, which were all higher than the approved standards have, chromium as the highest and nickel as the least. The anionic average relative abundance has hydrogen trioxocarbonate ion concentration as the highest and fluoride ions as the least. The survey demonstrates that leachate has a considerable impact on groundwater.

An FPGA-Based signal acquisition system for 3D holographic azimuthal electromagnetic resistivity logging instruments

Abstract A signal acquisition system of a 3D holographic azimuthal electromagnetic resistivity logging instrument while drilling is designed based on the Field Programmable Gate Array (FPGA). The azimuth electromagnetic wave resistivity logging instrument is mainly composed of transmitting coils, receiving coils, and control circuits. The signal acquisition system mainly includes the receiving coil and corresponding signal acquisition and processing circuit. First of all, the whole structure of the electromagnetic wave resistivity instrument system while drilling is briefly introduced, and then each function module of the acquisition board is elaborated in detail, and the hardware realization of the signal acquisition module and the corresponding FPGA program design flow chart are given. The acquisition system makes full use of the structured design of the module and First input First output (FIFO) cache technology and can complete the functions of signal acquisition, data transmission, and control on the acquisition board in real-time by using Serial Communication Interface (SCI) information transmission interface. The simulation results show that the system can realize the function of data acquisition and processing well.

Detecting the effect of soil compaction processes on the distribution of subsurface resistivity using 2D resistivity imaging

Detecting the effect of soil compaction processes on the distribution of subsurface resistivity using 2D resistivity imaging

Detecting the effect of soil compaction processes on the distribution of subsurface resistivity using 2D resistivity imaging

Detecting the effect of soil compaction processes on the distribution of subsurface resistivity using 2D resistivity imaging

Exploring the InSAR signature associated with river-sourced recharge in California’s San Joaquin Valley

Recharge is a critical component for understanding aquifer systems and the sustainable management of groundwater resources, yet this process is challenging to measure at policy-relevant spatiotemporal scales. Building upon previous research, we tested the hypothesis that InSAR can be used to observe river-sourced recharge if the underlying recharge pathways are associated with sufficient clay content. Our analysis leveraged the decomposition of InSAR time series with interpretations of 3D resistivity models derived from airborne electromagnetic (AEM) surveys. We focused our analysis on two study sites where high density AEM data were available and river-sourced recharge is determined to have occurred during wet years: (1) near Fresno, California and (2) near Visalia, California. Sediment type and hydrogeological structure from AEM supported our hypothesis with the InSAR signature attributed to river-sourced recharge occurring only in the study site with semi-confined to confined conditions and relatively high fraction of interbedded clay within recharge pathways. The timing to peak amplitude, the key feature we wanted to isolate in the InSAR data, near Visalia was interpreted as a pressure pulse front associated with river-sourced recharge propagating into the San Joaquin Valley. This study further validated the potential of InSAR, coupled with AEM data, to map and monitor river-sourced recharge in aquifer systems. As InSAR data become more accessible, this approach holds promise for broader applications in groundwater science and management worldwide.

An Attempt to Delineate Subsurface Ain Aldawar Cavity Using 2D Electrical Resistivity Imaging Method in Haditha Area, Western Iraq

The current study used 2D resistivity imaging to identify a shallow subsurface cavity in Haditha, western Iraq. The cavities and voids near the surface restrict land use and create a variety of geotechnical hazards, such as land subsidence, infrastructure damage, and structural cracks. As a result, the presence of an underground weak zone is a major concern for engineers before beginning any development, given the risk of future disasters. The four 2D resistivity traverses in this study were carried out using a dipole-dipole array with a - spacing of 3 m and an n-factor of 6. The data was inverted using RES2DINV software, which employs robust inversion methods. The 2D inverse model reveals a shallow cavity ranging from 5 to 12 meters and a width of around 40 m.

Effect of dumpsite on groundwater quality: A case study of bonny island rivers state

This study investigates the effect of dumpsite activities on groundwater quality in Bonny Island, Rivers State, Nigeria. Bonny Island, an ancient coastal city with significant economic importance due to its oil and gas industries, faces potential environmental threats from dumpsite activities. The research utilized vertical electrical sounding (VES) and 2D resistivity profiling (ERT) to assess subsurface contamination. Measurements were taken to determine the lateral and vertical spread of contaminants at the dumpsite. Complemented by laboratory analysis of groundwater samples from the two dumpsites, groundwater samples were analyzed for a range of physical, chemical, and biological parameters, such as pH, TDS, TSS, DO, Nitrates, Sulphates, Chlorides, heavy metals, and other pollutants. Results obtained indicate that the groundwater near the dumpsites exhibits varying levels of contamination. The VES and ERT profiles revealed low resistivity zones at shallow depths, indicating possible clay-rich soil or topsoil contamination from leachate. High resistivity areas in the middle depths suggest cleaner zones, but low resistivity at both ends of the profiles indicates further spread of the leachate. Laboratory analyses of groundwater sample showed that most parameters were within acceptable limits set by WHO and NSDWQ, except iron, which exceeded the permissible limit, suggesting contamination of iron at the site. These findings highlight the need for continuous monitoring and remediation efforts to prevent further deterioration of groundwater quality. This study underscores the critical importance of protecting groundwater in economically vital and ecologically sensitive regions like Bonny Island.

Magnetic and resistivity imaging of a probable fault within the Precambrian crystalline rocks in Ogbomoso, Southwestern Nigeria

A linear structure which is interpreted to be a fault was identified within the Precambrian basement complex rocks of the Ogbomoso Southwest Sheet 222 geological map, southwest Nigeria. The ground magnetic and electrical resistivity methods were used to investigate the structure and determine its physical characteristics. Five (5) traverses with lengths varying from 700–800 m and trending approximately NW–SE were established perpendicularly to the suspected fault. Total magnetic field data were acquired at 10 m interval, corrected for diurnal variation and inverted into 2D magnetic models using the Geosoft Oasis montaj software package. Dipole-Dipole resistivity data were acquired along the traverses using a dipole length of 20 m with expansion factor n varying from 1 to 5 and modelled to generate 2D resistivity structures with the DIPPROTM software package. Thirty-seven (37) depth sounding datasets were acquired, quantitatively interpreted and the results used to generate geoelectric sections across the suspected geologic feature. Three major magnetic dyke lineaments D1, D2 and D3 (60 – 164 m wide and 70 – ∞ depth extent) characterised by peak negative (−44 to −81 nT) magnetic anomalies and equivalent resistivity lineaments R1, R2 and R3 (50 – 140 m wide and 40 to >60 m depth extent) typified by low resistivity (10 – 750 Ωm) vertical discontinuities were delineated. The northern edges of lineaments D2 and R2 coincide significantly with the spatial location of the suspected fault F1 – F1 while D1 and R1 and D3 and R3 correlated and are newly identified parallel faults F2 – F2 and F3 – F3 to F1 – F1 and probably syngenetic with it.

The “Annunziata” Garden in Cammarata (Sicily): Results of integrated geophysical investigations and first archaeological survey

A multi-method geophysical investigation was carried out in the context of a recovery project for the “Annunziata” Garden located in the town of Cammarata (Sicily), near to the homonymous church (Chiesa dell'Annunziata). In this area, according to the scarce historical sources, there was a Benedictine convent, probably demolished in the 18th century, but the area was probably inhabited even in earlier periods. Preliminarily, a series of 2D electrical resistivity tomographies (2D-ERT) were carried out approximately parallel to each other, some of which highlighted resistivity anomalies that could be attributed to buried archaeological structures. Consequently, in a smaller area where these anomalies were evident, a 3D electrical resistivity tomography (3D-ERT) and Ground Penetrating Radar (GPR) parallel profiles were carried out aimed at a detailed 3D reconstruction of the subsoil. Despite the unclear correspondence between the 3D-ERT inverse model and the GPR one, the 3D ERT confirmed the anomalies found with the previous 2D-ERT surveys, better defining its contours and geometries. The geophysical reconstructions served to indicate to the archaeologists the most promising areas for excavation tests that were carried out subsequently and confirmed the presence of archaeological structures, such as defensive walls whose origin and dating are still the subject of further archaeological studies.

Enhancing DC resistivity data two-dimensional inversion result by using U-net based Deep learning- algorithm: Examples from archaegeophysical surveys

In this study, we suggested using a convolutional neural network (CNN) based algorithm to enhance two-dimensional (2D) Direct Current Resistivity (DCR) data inversion results. We developed U-net based CNN algorithm, named DCR2D_Net_Archaeo. We generated 1080 sets of 2D resistivity models that simulate buried archaeological remains. We calculated synthetic data for those models for different electrode arrays. We added 2% random noise to apparent resistivity data sets and inverted those data sets. We used the 2D inversion results as input and the corresponding real resistivity model as output. By using those 1080 input and output data sets we developed the DCR2D_Net_Archaeo algorithm. First, we tested this algorithm by using synthetic data. We showed that the developed algorithm improved the 2D classical smoothing regularization inversion and the buried body’'s geometry and depth can be found very close to the real model. Afterward, we also tested the developed algorithm with real data collected from two different archaeological sites. We showed that the buried wall cross-section location and depth are better found by the DCR2D_Net_Archaeo algorithm than by using the conventional inversion codes for the inversion of DCR data if we compare it with the excavated wall structure.

Three-dimensional triboelectric nanogenerator manufacturing using water transfer printing

Triboelectric nanogenerators (TENGs) have been widely studied due to their efficient energy harvesting capabilities and fast electrical response signals. In this study, a processing method based on water transfer printing (WTP) is developed for preparing TENG devices with three-dimensional (3D) structures. With this method, electrodes and ink layers can be integrated onto a variety of 3D objects to form a one-piece structure, which offers advantages including application to 3D surfaces, abrasion resistance, handling ease, adaptability, and decorativeness. The process istaken to prepare a 5 × 5 cm2 single-electrode TENG (IF-TENG), with FEP serving as the negative triboelectric layer and ink serving as the positive triboelectric layer. The TENG’s open-circuit voltage and short-circuit current are 184 V and 1.53 μA, respectively. Additionally, a door handle TENG (DH-TENG) device has been built for practical application demonstrations. The DH-TENG device is used in wireless alarm systems that prevent children from accidentally ingesting medication. It is also used in self-powered guidance systems that illuminate LED arrow lights to help the elderly or children at night. Seamless integration of 3D surface TENG devices using WTP is expected to have applications in smart home systems, smart transportation and security, wearable electronics, and energy harvesting.

Istraživanje opasnosti od curenja kod nasipa temeljeno na 3D električnoj tomografiji

Leakage is a common issue in reservoirs; however, accurately detecting its location and seepage diameter can be challenging owing to complex geological conditions. Three-dimensional (3D) resistivity tomography (RT), as opposed to traditional resistivity technology, offers advantages such as high observation density, efficiency, information richness, resolution, and intelligence. This study focuses on the application of 3D RT to diagnose leakage in earth and rock embankment dams. By monitoring the resistance change rate obtained from resistivity image processing, this study accurately assessed the development status of the hidden bodies. This research demonstrates that 3D RT enables rapid comparison of deformation and damage states at different moments, enabling continuous and objective monitoring of earth and rock embankment dams. This technology is comprehensive and provides real-time insights.

Research and Application of the Mine 3D DC Resistivity Method for Detecting Grouting in the Floor of an Ultrawide Working Face, Taking the Yongmei Xinqiao Coal Mine in Henan Province as an Example

Generally, ground grouting is used to treat confined water areas before mining at the working face, but there is a lack of testing methods for determining the effectiveness of such a grouting treatment on the floor of ultrawide working faces. Therefore, we propose a 3D DC resistivity method for mines and apply it to the detection of the effect of grouting on the mine floor. This study took the Yongmei Xinqiao Coal Mine in Henan Province as the research object and used a combination of theoretical analysis, numerical simulation, and measured data analysis to study the effect of the 3D resistivity method on detecting the effect of grouting on the floor of an ultrawide working face in the mine. The research results indicated that compared with the 2D observation mode of same-side power supply and reception, the 3D observation mode of opposite-side power supply and reception using the tunnels on both sides of the working face was more sensitive to the response of the water-rich area 60 m below the coal seam’s floor. Regarding the model’s set-up in this article, when traditional apparent resistivity calculations were used, the apparent resistivity obtained by the 3D observation mode was opposite to the model’s setting, and accurate electrical information of anomalous bodies must be obtained through 3D inversion. The measured data showed that although the ground grouting treatment effectively reduced the water volume in the floor, the treatment’s result was affected by human factors, and the water in the floor was redistributed.

Constraints on Growth and Stabilization of the Western Superior Craton From Inversion of Magnetotelluric Data

AbstractA data set consisting of 376 broadband and long‐period MT measurements was used to generate the first ever 3D resistivity model of the Archean western Superior Craton. The modeled resistivity structure is compared to coincident seismic reflection data. The observed geophysical signatures are interpreted within the context of the late stages of crustal growth and cratonization of the region via the progressive accretion of terranes against the initial cratonic core. The northern‐most terranes comprising the cratonic core exhibit a nearly homogenous highly resistive crust. The lower crust of the southern terranes contains largely continuous low resistivity bands which run subparallel to major terrane boundaries and corresponding fault systems. In some cases, low resistivity features are coincident with dense packages of sub‐horizontal to listric reflections within the mid‐ to lower crust. These resistivity structures are inferred to represent preserved geoelectric signatures of late to post‐orogenic magmatic pulses likely related to delamination of locally overthickened crust. Increased mantle heat flow resulted in partial melting of the lower crust and upper mantle and upward migration of CO2‐rich melts and fluids through crustal weak zones corresponding to shear and/or suture zones formed during terrane amalgamation. Thermal softening of the mid‐ to lower crust led to orogenic collapse and reactivation of the crustal shear zones, resulting in formation and interconnection of graphitic films which were preserved within the stable craton. These results have implications for the tectono‐magmatic history of the western Superior Craton, as well toward the understanding of the geodynamic regime of the Archean Earth.

Evaluation of strain-sensitive behavior in elastomeric conductive nanocomposites containing carbon nanotubes-a finite element-percolation model approach

A finite element (FE)-percolation model approach is developed to predict the strain-sensitive response of the three-dimensional (3D) representative volume element (RVE) of carbon nanotube (CNT)-elastomeric nanocomposite. In the simulation model, CNTs are modeled as solid, impenetrable cylinders inside a cubic insulating matrix. FE simulation is performed to evaluate the structural response of the RVE under applied strain. The FE model updates the locations of the CNTs in the deformed RVE. The paths are found using a suitable 3D resistance network associated with different percolation paths involved in the critical distance criterion. The percolation model utilizes the paths found to identify the electrical circuit for predicting tunneling conductivity. The simulating algorithm is used to study the influence of tunneling barrier height, nanotube volume fraction, and geometrical aspects. The lowest critical distance criterion is achieved for higher volume fractions and the most heightened sensitivity is obtained for lower CNT aspect ratios.

Identification of Seawater Intrusion in Groundwater using The Wenner-Schlumberger Configuration (2D) Geoelectric Resistivity Method on Balu Island, Santiri Village, Tiworo Utara Sub-District, West Muna Regency

This research aims to identify sea water intrusion in groundwater using the Wenner-Schlumberger configuration (2D) resistivity geolectric method on Balu Island, Santiri village, Tiworo Utara sub-District, West Muna Regency. This research uses primary data which is resistivty measurement data measured in the field aimed at identifying groundwater aquifers. The interpretation data is then reconstructed into 2D cross-sectional profile using Res2Dinv software. The results obtained in the research area show that sea water intrusion has occurred in groundwater at an average surface depth of up to 39.6 meters with low resistivity values ​​between 0.06 – 807 Ohm-meters

1D Audio Magnetotelluric Modelling for Deep Aquifer Identification in the Lava Fan Area of Haruman Peak, Malabar Mountains

The Malabar Mountains area acts as a catchment and infiltration zone for rainwater. Haruman Peak is the location of one of these areas. Information on the well-preserved depth of the shallow aquifer at 40 meters reinforces this. This research reviews the results of subsurface 1D resistivity structures from AMT data to obtain information on the depth of deep aquifers on the western slope of the Haruman Peak Lava Fan, Haruman Mountains. 1D modelling shows an aquifer at depth of 140.56-2080.07 meters with resistivity ranging from 5.25-68.08 Ωm. At depths of 453.32 m (HR02), 530.8 m (HR03), 1464.97 m (HR01), and 2080.07 m (HR02), interbedded tuff-andesite with minor pumice identifies the deep aquifer. In addition, a depth of 140.56 m (HR02) with a resistivity value of 68.08 Ωm indicates a shallow aquifer. Looking at the elevation of the Bandung Basin, water from aquifers located at elevations > 700 meters above sea level will flow into the Bandung Basin.