Identification of leakage and potential areas for internal erosion combining ERT and IP techniques at the Negratín Dam left abutment (Granada, southern Spain)

Martínez-Moreno, F.J.; Delgado-Ramos, Fernando; Galindo-Zaldı́var, Jesús; Martín-Rosales, W.; López-Chicano, M.; González-Castillo, Lourdes

doi:10.1016/j.enggeo.2018.04.012

Cited by 45 publications

(16 citation statements)

References 30 publications

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“…Initially developed for mineral exploration (e.g., Van Voorhis et al, 1973), induced polarization has then been recently used for environmental applications (Binley et al, 2005(Binley et al, , 2015. Recent applications include the study of leakage detections in embankments and dams (Abdulsamad et al, 2019;Martínez-Moreno et al, 2018) and the study of contaminated areas (Sogade et al, 2006;Binley et al, 2015). To the best of our knowledge, induced polarization has never been used to study the water content of rammed earth materials.…”

Section: Introductionmentioning

confidence: 99%

Complex conductivity of rammed earth

Abdulsamad

Revil

Prime

et al. 2020

Engineering Geology

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Searching for recyclable materials of construction, in the objective of building sobriety and resilience, is a major issue of our current societies. Mudbricks of compacted rammed earth represent an ancient construction material with many advantages associated with its availability, cost of production, potential reuse, and with a very low carbon footprint. Moisture content affects the mechanical resistance of such materials, which could become mechanically weak above a critical value. Therefore, non-intrusive characterization techniques able to image the water content distribution of these materials is highly in demand. We apply a recently developed theory of complex electrical conductivity (alias induced polarization) to characterize core samples of rammed earth materials in the laboratory. Complex conductivity describes both the ability of a porous material to conduct an electrical current (characterized by the in-phase conductivity) and its ability to store reversibly electrical charges (characterized by two interconnected properties namely the quadrature conductivity and the normalized chargeability). Samples of rammed earth and clayey soils with different pore water salinities, saturations, and compaction states are measured with the complex conductivity method in the frequency range 100 mHz-45 kHz. The in-phase and quadrature conductivities of the complex conductivity of rammed earth are connected to the water content offering therefore a new non-intrusive tomographic technique to study the water content distribution in walls made of rammed earth. The data are all consistent with the so-called dynamic Stern layer model of complex conductivity for clayey materials. This new approach provides a general method to image the change in the water content of walls made of rammed earth, a task that electrical conductivity imaging cannot perform as a stand-alone technique.

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Section: Introductionmentioning

confidence: 99%

Complex conductivity of rammed earth

Abdulsamad

Revil

Prime

et al. 2020

Engineering Geology

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“…Thus, the IP method is complementary to the ERT and has been proven to be very useful in searching gold deposits, massive ore sulphides, graphite or bentonite deposits, as well as in investigating the contamination of aquifers by organic or inorganic substances [4,5,11,21,22]. The combination of these techniques has also been used in the detection of deeply buried caves [23], seepage [24] and slope stability [25].…”

Section: Introductionmentioning

confidence: 99%

Geophysical Prospecting Using ERT and IP Techniques to Locate Galena Veins

Martínez

Rey

Sandoval³

et al. 2019

Remote Sensing

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The aim of this study is to prove the effectiveness of two electrical geophysical prospecting techniques, namely electrical resistivity tomography (ERT) and induced polarization (IP), in locating thin vein structures of metal sulphides embedded in Palaeozoic materials underlying a sedimentary cover. For this purpose, a Quaternary basin known as La Garza was selected, located in the mining district of Linares-La Carolina (Southern Spain). Galena (PbS) veins appear abundantly throughout this area, hosted in the Palaeozoic granitic bedrock. The studied veins show thicknesses from 0.5 to 2.0 m, and most present a vertical planar distribution. The veins lose their continuity below the sedimentary cover due to normal fractures that control the subsidence of the basin. During the 1980s, geophysical research campaigns were carried out in La Garza using vertical electrical sounding and failed in detecting the hidden veins. For this reason, to carry out this study, a closed regular mesh was designed, composed by eight ERT and IP profiles, with variable lengths between 315 and 411 metres. An electrode spacing between 5 and 7 metres was selected, thus allowing the granite bedrock to be reached without significantly reducing the resolution capabilities of the method. Even though ERT and IP are well-known geophysical techniques for mapping ore deposits, this is a case study that shows the advantages of the simultaneous use of both techniques (ERT and IP), over their individual application. ERT allows for reconstructing the morphology of the basin and the fractures that control it due to high-resistivity contrast between the overlying sedimentary cover and the underlaying granitic basement. However, it cannot provide any insights about their degree of mineralization. At this point, it is the IP technique that makes it possible to differentiate which are the mineralized structures. Some of these fractures produce high (above 50 mV/V) and moderate (below 50 mV/V) chargeability values, suggesting the existence of several unexploited metal veins. Furthermore, the derived models enable researchers to analyse the morphology of this sedimentary basin controlled by normal faults.

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“…Different geophysical methods can be used to detect preferential flow paths in embankment dams and dikes including ground penetrating radar, passive and active seismic methods (Himi et al, 2018), and geoelectrical (galvanometric) methods including the self-potential method (Al-Saigh et al, 1994) and electrical conductivity and induced polarization methods (e.g., Martínez-Moreno et al, 2018). Ground Penetrating Radar (GPR) constitutes a fast and reliable method for shallow investigations.…”

Section: Introductionmentioning

confidence: 99%

Induced polarization tomography applied to the detection and the monitoring of leaks in embankments

Abdulsamad

Revil

Ahmed

et al. 2019

Engineering Geology

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During an induced polarization survey, both electrical conductivity and chargeability can be imaged. Recent petrophysical models have been developed to provide a consistent picture of these two parameters in terms of water and clay contents of soils. We test the ability of this method at a test site in which a controlled artificial leakage can be generated in an embankment surrounding an experimental basin. 3D tomography of the conductivity and normalized chargeability are performed during such a controlled leakage. Conductivity and induced polarization measurements were also performed on a core sample from the site. The sample was also characterized in terms of porosity and cation exchange capacity. Combining the 3D survey and these laboratory measurements, a 3D tomogram of the relative variation in water content (before leakage and during leakage) was estimated. It clearly exhibits the ground water flow path through the embankment from the outlet of the tube used to generate the leak to the bottom of the embankment. In addition, a self-potential survey was performed over the zone of leakage. This survey evidences also the projection of the ground water flow path over the ground surface. Both methods are found to provide a consistent picture. A 2.5D time lapse tomography of the electrical conductivity and normalized chargeability was also performed and evidences the position of the preferential flow paths below the profile. These results confirm the ability and efficiency of induced polarization to provide reliable information pertaining to the detection of leakages in dams and embankments.

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Identification of leakage and potential areas for internal erosion combining ERT and IP techniques at the Negratín Dam left abutment (Granada, southern Spain)

Cited by 45 publications

References 30 publications

Complex conductivity of rammed earth

Complex conductivity of rammed earth

Geophysical Prospecting Using ERT and IP Techniques to Locate Galena Veins

Induced polarization tomography applied to the detection and the monitoring of leaks in embankments

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