Resistivity Imaging for Mapping of Quick Clays for Landslide Risk Assessment

Dahlin, Torleif; Leroux, Virginie; Larsson, Rolf; Rankka, Karin

doi:10.3997/2214-4609-pdb.13.a046

Cited by 7 publications

(3 citation statements)

References 3 publications

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“…Recently there has been some work published on the use of geoelectrical measurements for mapping quick clay. These field studies have compared measured resistivity values with salt content (Söderblom ; Solberg et al ), as well as remoulded strength and sensitivity (Rankka et al ; Dahlin et al ; Lundström et al ). Unleached marine clay, which maintains a large concentration of ions in its pore water, has been shown to have very low values of resistivity, generally less than 10 Ωm.…”

Section: Introductionmentioning

confidence: 99%

Multi‐method geophysical mapping of quick clay

Donohue

Long

O’Connor³

et al. 2012

Near Surface Geophysics

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The UCD community has made this article openly available. Please share how this access benefits you. Your story matters! (@ucd_oa) Some rights reserved. For more information, please see the item record link above. ABSTRACT Marine clay deposits in coastal, post-submarine areas of Scandinavia and North America may be subjected to quick clay landslides and hence significant efforts are being taken to map their occurrence and extent. The purpose of this paper is to assess the use of a number of geophysical techniques for identifying quick clay. The investigated area, Smørgrav, located in southern Norway has a history of quick clay sliding, the most recent event occurring in 1984. Geophysical techniques that are used include electromagnetic conductivity mapping, electrical resistivity tomography, seismic refraction and multichannel analysis of surface waves. These results are compared to geotechnical data from bore samples, rotary pressure soundings and cone penetration testing. A number of these approaches have proved promising for identifying quick clay, in particular electrical resistivity tomography and electromagnetics, which delineated a zone of quick clay that had previously been confirmed by rotary pressure soundings and sampling. Seismic refraction was useful for determining the sediment distribution as well as for indicating the presence of shallow bedrock whereas the multichannel analysis of surface-waves approach suggested differences between the intact stiffness of quick and unleached clay. It is observed that quick clay investigations using discrete rotary pressure soundings can be significantly enhanced by using, in particular, electrical resistivity tomography profiles to link together the information between test locations, perhaps significantly reducing the need for large numbers of soundings.

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Section: Introductionmentioning

confidence: 99%

Multi‐method geophysical mapping of quick clay

Donohue

Long

O’Connor³

et al. 2012

Near Surface Geophysics

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“…In recent decades, there has been an increasing interest in integrating geophysical monitoring techniques with other technologies to assess the stability of slopes and embankments to mitigate hydrogeological risks [ 1 , 2 ]. Most long-term monitoring systems have been developed using microseismic networks to detect the seismic energy released by unstable slopes [ 3 , 4 , 5 , 6 ] or geoelectrical methods to monitor the hydrogeological conditions of slopes and embankments [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. Among different geophysical techniques, electrical resistivity tomography (ERT) method has a long history in solving a variety of engineering, environmental and hydrogeological problems [ 14 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

An Iterative 3D Correction plus 2D Inversion Procedure to Remove 3D Effects from 2D ERT Data along Embankments

Hojat

2024

Sensors

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This paper addresses the problem of removing 3D effects as one of the most challenging problems related to 2D electrical resistivity tomography (ERT) monitoring of embankment structures. When processing 2D ERT monitoring data measured along linear profiles, it is fundamental to estimate and correct the distortions introduced by the non-uniform 3D geometry of the embankment. Here, I adopt an iterative 3D correction plus 2D inversion procedure to correct the 3D effects and I test the validity of the proposed algorithm using both synthetic and real data. The modelled embankment is inspired by a critical section of the Parma River levee in Colorno (PR), Italy, where a permanent ERT monitoring system has been in operation since November 2018. For each model of the embankment, reference synthetic data were produced in Res2dmod and Res3dmod for the corresponding 2D and 3D models. Using the reference synthetic data, reference 3D effects were calculated to be compared with 3D effects estimated by the proposed algorithm at each iteration. The results of the synthetic tests showed that even in the absence of a priori information, the proposed algorithm for correcting 3D effects converges rapidly to ideal corrections. Having validated the proposed algorithm through synthetic tests, the method was applied to the ERT monitoring data in the study site to remove 3D effects. Two real datasets from the study site, taken after dry and rainy periods, are discussed here. The results showed that 3D effects cause about ±50% changes in the inverted resistivity images for both periods. This is a critical artifact considering that the final objective of ERT monitoring data for such studies is to produce water content maps to be integrated in alarm systems for hydrogeological risk mitigation. The proposed algorithm to remove 3D effects is thus a rapid and validated solution to satisfy near-real-time data processing and to produce reliable results.

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“…More recently, geophysical methods have been used for quick‐clay mapping. These methods include Electrical Resistivity Tomography (ERT) (e.g., Ranka et al ; Dahlin et al ; Solberg et al 2008) and Resistivity CPTU (RCPTU) (e.g., Rømoen et al ; Sauvin et al ; Solberg et al ) for calibration and refraction seismic for bedrock mapping and in a few cases Multi‐channel Analysis of Surface waves (MASW) (Sauvin et al ; Donohue et al ).…”

Section: Introductionmentioning

confidence: 99%

Towards geophysical and geotechnical integration for quick‐clay mapping in Norway

Sauvin

Lecomte

Bazin

et al. 2012

Near Surface Geophysics

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Quick clay is a known hazard in formerly‐glaciated coastal areas in e.g., Norway, Sweden and Canada. In this paper, we review the physical properties of quick clays in order to find a suitable, integrated and multi‐disciplinary approach to improve our possibilities to accurately identify the occurrence of quick clay and map its extent both vertically and laterally. As no single geophysical method yields optimal information, one should combine a variety of geophysical methods with geotechnical data (in situ measurements using Cone Penetration Testing (CPTU), Seismic CPTU (SCPTU) and Resistivity CPTU (RCPTU); laboratory tests) for an in‐depth quick‐clay assessment at a given site. In this respect, geophysical data are used to fill the gaps between geotechnical boreholes providing ground‐truth. Such an integrated and multi‐disciplinary approach brings us closer to 2D or pseudo‐3D site characterization for quick clays and as such, an improved assessment of the potential hazard they pose. The integrated approach is applied in practice on two Norwegian quick‐clay sites. The first site, Hvittingfoss, was remediated against potential landslides in 2008 whereas the second one, Rissa, was the scene of a major quick‐clay landslide in 1978, quick clays being still present over a large area. The collected data and preliminary site characterizations illustrate the high diversity as well as the complexity and clearly emphasize the need for higher resolution, careful imaging and calibration of the data in order to accomplish the assessment of a quick‐clay hazard.

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Resistivity Imaging for Mapping of Quick Clays for Landslide Risk Assessment

Cited by 7 publications

References 3 publications

Multi‐method geophysical mapping of quick clay

Multi‐method geophysical mapping of quick clay

An Iterative 3D Correction plus 2D Inversion Procedure to Remove 3D Effects from 2D ERT Data along Embankments

Towards geophysical and geotechnical integration for quick‐clay mapping in Norway

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