Stabilization Methodology in Foundation Soils by ERT-3D Application in Estepona, South Spain

The paper proposes a novel methodology for the stabilization of shallow foundations, with a simplified model combined with 3D electrical resistivity tomography (ERT-3D and consolidation injections. To determine its usefulness, the method has been applied in a case located in Estepona (southern Spain). The chosen tomography model is the dipole–dipole configuration, with an optimized distance between electrodes of 0.80 m for a better visualization of the foundation subsoil; with this parameterization, a total of 72 electrodes were installed in the analyzed case. In this work, the depth of the anomaly in the building’s supporting subsoil was detected ranging from 2.00 m to 3.90 m deep. The study also delineates areas of high resistivity variations (50–1000 Ω m) in the middle and eastern end of the field. These data have been validated and corroborated with a field campaign. The results of the ERT-3D monitoring are presented, once the investment data has been processed with the RES3DINV software, from the beginning to the end of the stabilization intervention. The novelty occurs with the interaction between the tomography and the foundation consolidation injections, until the final stabilization. This is a very useful methodology in case of emergency consolidation, where there is a need to minimize damage to the building. Thus, people using this combined system will be able to practically solve the initial anomalies of the subsoil that caused the damages, in a non-invasive way, considerably lowering the value of the resistivities.

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Stabilization methodology in foundation soils by ERT-3D. Application in Estepona, South Spain.

10.20944/preprints202104.0406.v1 ◽

2021 ◽

Author(s):

Alfonso Gutiérrez-Martín ◽

José I. Yenes ◽

Marta Fernández-Hernández ◽

Ricardo Castedo

Keyword(s):

Electrical Resistivity ◽

Electrical Resistivity Tomography ◽

Shallow Foundations ◽

Simplified Model ◽

High Resistivity ◽

Combined System ◽

Resistivity Tomography ◽

Field Campaign ◽

Non Invasive ◽

Dipole Configuration

The paper proposes a novel methodology for the stabilization of shallow foundations, with a simplified model combined with 3D Electrical resistivity tomography (ERT-3D) and conso- lidation injections. To determine its usefulness, the method has been applied in a case located in Estepona (southern Spain). The chosen tomography model is the dipole-dipole configuration, with an optimized distance between electrodes of 0.80 m for a better visualization of the foundation subsoil; with this parameterization, a total of 72 electrodes were installed in the analyzed case. In this work, the depth of the anomaly in the building's supporting subsoil was detected ranging from 2.00 m to 3.90 m deep. The study also delineates areas of high resistivity variations (50-1,000 Ω m) in the middle and eastern end of the field. These data have been validated and corroborated with a field campaign. The results of the ERT-3D monitoring are presented, once the investment data has been processed with the RES3DINV software, from the beginning to the end of the stabilization intervention. The novelty occurs with the interaction between the tomography and the foundation consolidation injections, until the final stabilization; very useful methodology in case of emergency consolidation, where there is a need to minimize damage to the building. Thus, people using this combined system; will be able to practically solve the initial anomalies of the subsoil that caused the damages, in a non-invasive way, considerably lowering the value of the resistivities.

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Non-invasive time-lapse imaging of moisture content changes in earth embankments using electrical resistivity tomography (ERT)

Advances in Transportation Geotechnics ◽

10.1201/9780203885949.pt6 ◽

2008 ◽

pp. 475-480 ◽

Cited By ~ 4

Author(s):

R Tilden Smith ◽

J Chambers ◽

G Ghataora ◽

M Burrow ◽

R Ogilvy ◽

...

Keyword(s):

Electrical Resistivity ◽

Moisture Content ◽

Electrical Resistivity Tomography ◽

Time Lapse ◽

Resistivity Tomography ◽

Non Invasive ◽

Time Lapse Imaging

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Electrical resistivity tomography applied to geologic, hydrogeologic, and engineering investigations at a former waste-disposal site

Geophysics ◽

10.1190/1.2360184 ◽

2006 ◽

Vol 71 (6) ◽

pp. B231-B239 ◽

Cited By ~ 133

Author(s):

Jonathan E. Chambers ◽

Oliver Kuras ◽

Philip I. Meldrum ◽

Richard D. Ogilvy ◽

Jonathan Hollands

Keyword(s):

Electrical Resistivity ◽

Electrical Resistivity Tomography ◽

Site Investigation ◽

High Resistivity ◽

Potential Zone ◽

Resistivity Tomography ◽

L2 Norm ◽

Resistivity Model ◽

2D And 3D ◽

2D Resistivity

A former dolerite quarry and landfill site was investigated using 2D and 3D electrical resistivity tomography (ERT), with the aims of determining buried quarry geometry, mapping bedrock contamination arising from the landfill, and characterizing site geology. Resistivity data were collected from a network of intersecting survey lines using a Wenner-based array configuration. Inversion of the data was carried out using 2D and 3D regularized least-squares optimization methods with robust (L1-norm) model constraints. For this site, where high resistivity contrasts were present, robust model constraints produced a more accurate recovery of subsurface structures when compared to the use of smooth (L2-norm) constraints. Integrated 3D spatial analysis of the ERT and conventional site investigation data proved in this case a highly effective means of characterizing the landfill and its environs. The 3D resistivity model was successfully used to confirm the position of the landfill boundaries, which appeared as electrically well-defined features that corresponded extremely closely to both historic maps and intrusive site investigation data. A potential zone of leachate migration from the landfill was identified from the electrical models; the location of this zone was consistent with the predicted direction of groundwater flow across the site. Unquarried areas of a dolerite sill were imaged as a resistive sheet-like feature, while the fault zone appeared in the 2D resistivity model as a dipping structure defined by contrasting bedrock resistivities.

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Application of Electrical Resistivity Tomography for Detecting Root Biomass in Coffee Trees

International Journal of Geophysics ◽

10.1155/2013/383261 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 10

Author(s):

Carlos Mauricio Paglis

Keyword(s):

Electrical Resistivity ◽

Root Biomass ◽

Electrical Resistivity Tomography ◽

Mass Density ◽

Plant Root ◽

Soil Layer ◽

Soil Resistivity ◽

Resistivity Tomography ◽

Coffee Plantations ◽

Dipole Configuration

Roots play an important role in plants and are responsible for several functions; among them are anchorage and nutrient and water absorption. Several methodologies are being tested and used to study plant root systems in order to avoid destructive root sampling. Electrical resistivity tomography is among these methodologies. The aim of this preliminary study was to use electrical resistivity for detecting root biomass in coffee trees. Measurements were performed in a soil transect with an ABM AL 48-b resistivimeter with a pole-dipole configuration. The tomograms indicated variability in soil resistivity values ranging from 120 to 1400 Ω·m−1. At the first 0.30 cm soil layer, these values were between 267 and 952 Ω·m−1. Oriented by this result, root samples were taken at 0.10, 0.20, and 0.30 m depths within 0.50 m intervals along the soil transect to compare soil resistivity with root mass density (RMD). RMD data, up to this depth, varied from 0.000019 to 0.009469 Mg·m−3, showing high spatial variability and significant relationship to the observed values of soil resistivity. These preliminary results showed that the electrical resistivity tomography can contribute to root biomass studies in coffee plants; however, more experiments are necessary to confirm the found results in Brazil coffee plantations.

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Exploring the regolith with electrical resistivity tomography in largescale surveys: electrode spacing related issues and possibility

10.5194/hess-2020-374 ◽

2020 ◽

Author(s):

Laurent Gourdol ◽

Rémi Clément ◽

Jérôme Juilleret ◽

Laurent Pfister ◽

Christophe Hissler

Keyword(s):

Electrical Resistivity ◽

Apparent Resistivity ◽

Large Scale ◽

Electrical Resistivity Tomography ◽

Subsurface Layer ◽

Electrode Spacing ◽

High Resistivity ◽

Constant Thickness ◽

Resistivity Tomography

Abstract. Within the Critical Zone, regolith plays a key role in the fundamental hydrological functions of water collection, storage, mixing and release. Electrical Resistivity Tomography (ERT) is recognized as a remarkable tool for characterizing the geometry and properties of the regolith, overcoming limitations inherent to conventional borehole-based investigations. For exploring shallow layers, a small electrode spacing (ES) will provide a denser set of apparent resistivity measurements of the subsurface. As this option is cumbersome and time-consuming, smaller ES – albeit offering poorer shallow apparent resistivity data – are often preferred for large horizontal ERT surveys. To investigate the negative trade-off between larger ES and reduced accuracy of the inverted ERT images for shallow layers, we use a set of synthetic conductive/resistive/conductive three-layered soil–saprock/saprolite–bedrock models in combination with a reference field dataset. Our results suggest that an increase in ES causes a deterioration of the accuracy of the inverted ERT images in terms of both resistivity distribution and interface delineation and, most importantly, that this degradation increases sharply when the ES exceeds the thickness of the top subsurface layer. This finding, which is obvious for the characterization of shallow layers, is also relevant even when solely aiming for the characterization of deeper layers. We show that an oversized ES leads to overestimations of depth to bedrock and that this overestimation is even more important for subsurface structures with high resistivity contrast. To overcome this limitation, we propose adding interpolated levels of surficial apparent resistivity relying on a limited number of ERT profiles with a smaller ES. We demonstrate that our protocol significantly improves the accuracy of ERT profiles when using large ES, provided that the top layer has a rather constant thickness and resistivity. For the specific case of large-scale ERT surveys the proposed upgrading procedure is cost-effective in comparison to protocols based on small ES.

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Ground penetrating radar and electrical resistivity tomography for locating buried building foundations: A case study in the city centre of Thessaloniki, Greece

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.10946 ◽

2016 ◽

Vol 47 (3) ◽

pp. 1355

Author(s):

G. Vargemezis ◽

N. Diamanti ◽

I. Fikos ◽

A. Stampolidis ◽

Th. Makedon ◽

...

Keyword(s):

Electrical Resistivity ◽

Ground Penetrating Radar ◽

Electrical Resistivity Tomography ◽

Geophysical Methods ◽

Geological Structure ◽

City Centre ◽

High Resistivity ◽

Resistivity Tomography ◽

Ground Penetrating ◽

The City

Ground penetrating radar (GPR) and electrical resistivity tomography (ERT) surveys have been carried out in the city centre of Thessaloniki (N. Greece), for investigating possible locations of buried building foundations. Geophysical survey has been chosen as a non-destructive investigation method since the area is currently used as a car parking and it is covered by asphalt. The geoelectrical sections derived from ERT data in combination with the GPR profiles provided a broad view of the subsurface. Regarding ERT, high resistivity values can be related to buried building remains, while lower resistivity values are more related to the surrounding geological materials. GPR surveying can also indicate man-made structures buried in the ground. Even though the two geophysical methods are affected in different ways by the subsurface conditions, the processed underground images from both techniques revealed great similarity. High resistivity anomalies and distinct GPR signals were observed in certain locations of the area under investigation, which are attributed to buried building foundations as well as the geological structure of the area.

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A 2D electrical resistivity tomography survey of a vineyard plot of the Gaillac appellation (France): interpretation with respect to possible implications on vine water supply

OENO One ◽

10.20870/oeno-one.2010.44.2.1462 ◽

2010 ◽

Vol 44 (2) ◽

pp. 51

Author(s):

Pierre Courjault-Radé ◽

Muriel Llubes ◽

José Darrozes ◽

Marguerite Munoz ◽

Eric Maire ◽

...

Keyword(s):

Electrical Resistivity ◽

Water Supply ◽

Electrical Resistivity Tomography ◽

Lower Layer ◽

Temporal Variations ◽

Climatic Conditions ◽

Morphological Data ◽

Subsurface Water ◽

High Resistivity ◽

Resistivity Tomography

Aims: The aim of this 2D electrical resistivity tomography (ERT) survey performed on a vineyard plot of the Gaillac appellation was to investigate spatial and temporal variations in subsurface water supply in relation with pedo-geological and morphological features.Methods and results: The ERT surveys were carried out under two contrasted - dry and humid - climatic conditions. All the resistivity profiles showed the superposition of two layers: a lower layer characterized by very low resistivity values (< 40 Ω.m) corresponding to a marly molassic subsoil overlaid by an upper layer characterized by moderate to high resistivity values (300 Ω.m to 1500 Ω.m) corresponding to a silty-sandy and gravely-pebbly soil sequence. The resistivity values of the molassic subsoil stayed very low independently of water supply conditions whereas those of the soil sequence decreased by a factor 2 (300/750 Ω.m versus 750/1500 Ω.m) when the plot was close to field capacity.Conclusion: The ERT results coupled with pedological and morphological data strongly suggest that the water flow is preferentially restricted at the molassic subsoil/soil sequence interface, short-lived and of low amplitude.Significance and impact of the study: Consequently, the water supply regime, which points out a potential risk of drought stress for vine crops, implies a minimization strategy when choosing vegetal material and viticultural management operations

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Applying Electrical Resistivity Tomography in Ornamental Stone Mining: Challenges and Solutions

Minerals ◽

10.3390/min8110491 ◽

2018 ◽

Vol 8 (11) ◽

pp. 491 ◽

Cited By ~ 3

Author(s):

Sebastian Uhlemann ◽

Jonathan Chambers ◽

W. Falck ◽

Avelino Tirado Alonso ◽

José Fernández González ◽

...

Keyword(s):

Electrical Resistivity ◽

Electrical Resistivity Tomography ◽

Radar Data ◽

Resistivity Tomography ◽

Non Invasive ◽

Ornamental Stone ◽

Resistivity Model ◽

Independent Observations ◽

Ground Penetrating ◽

Resistivity Meter

In this study, the use of electrical resistivity tomography (ERT) as a tool to guide ornamental stone extraction is investigated. ERT is not conventionally used in highly resistive environments, such as on rock faces, due to the high contact resistances that can impede current injection. Here, the challenges of conducting ERT in such environments are discussed and possible solutions suggested. For this, an example of the application of ERT in a deep and narrow marble quarry is used. The marble deposit is affected by fracturing and karstification. Due to the nature of these features, they present a significant resistivity contrast to the background resistivity of the marble and thus excellent targets to test the application of ERT. Their location was mapped using field observations and complementary ground penetrating radar data. By using an appropriate sensor deployment, a suitable resistivity meter, and advanced data processing routines, the derived 3D resistivity model is in good agreement with the independent observations. This shows that despite the challenges, ERT can be used as a non-invasive tool to obtain information on the stone properties prior to extraction. This will help in guiding quarry operations and will allow for a targeted, safe and efficient extraction of high quality stone, thereby increasing sustainability and economical competitiveness.

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Characterization of Aquifers in Metamorphic Rocks by Combined Use of Electrical Resistivity Tomography and Monitoring of Spring Hydrodynamics

Geosciences ◽

10.3390/geosciences10040137 ◽

2020 ◽

Vol 10 (4) ◽

pp. 137

Author(s):

Maja Briški ◽

Andrej Stroj ◽

Ivan Kosović ◽

Staša Borović

Keyword(s):

Electrical Resistivity ◽

Electrical Resistivity Tomography ◽

Crystalline Rocks ◽

High Resistivity ◽

Alteration Zone ◽

Spring Discharge ◽

Resistivity Tomography ◽

Alteration Zones ◽

Alteration Processes

Crystalline rocks are generally characterized by negligible porosity and permeability in terms of groundwater exploitability. However, alteration processes can greatly increase their fracture permeability and induce formation of modest, but locally important aquifers. Therefore, subsurface characteristics of alteration zones are of major importance for hydrogeological evaluation of crystalline terrains. Alteration processes greatly affect rock total porosity and water content, causing contrasting electrical resistivity of rocks affected by varying degrees of weathering. This makes electrical resistivity tomography (ERT) a preferable geophysical method for the exploration of alteration zones in crystalline rocks. In our research, we used an integrated approach, combining the ERT method with monitoring of spring discharge and hydrochemistry to characterize metamorphic aquifers on slopes of the Medvednica Mountain (Croatia). Significant fracture flow aquifers are found to be formed in intensely fractured but not highly weathered rock masses (medium to high resistivity values), while highly weathered masses (low resistivity values) form local barriers for fracture flows. Subsurface structure of the alteration zone proved to be highly irregular, with sharp contacts between more and less weathered rocks. Decrease of permeability below the alteration zone keeps the water level near the surface and enables spring occurrence on the mountain slopes. Studied aquifers have relatively limited extent, resulting in typical capacity of major springs of a few l/s. More frequent but less productive springs are attributed to the draining of the shallow part of the alteration zone (mostly saprolite). Combination of the ERT method with spring monitoring proved to be very effective as a first and relatively inexpensive methodology for hydrogeological characterization of crystalline terrains, both in local and catchment scales.

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