Moisture monitoring in clay embankments using electrical resistivity tomography

Gunn, David; Chambers, Jonathan; Uhlemann, S.; Wilkinson, P.B.; Meldrum, Philip; Dijkstra, Tom; Haslam, Edward; Kirkham, Matthew; Wragg, Joanna; Holyoake, S.; Hughes, Paul; Hen-Jones, Rose; Glendinning, S. G.

doi:10.1016/j.conbuildmat.2014.06.007

Cited by 100 publications

(48 citation statements)

References 20 publications

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“…Noninvasive geophysical methods, which are capable of estimating physical properties of significant volumes of the subsurface, are well-suited for this application (Donohue et al, 2011). Electrical resistivity tomography (ERT) (Loke and Barker, 1996), for example, has, over recent years, been used for near-surface time-lapse imaging of natural slopes and landslides (e.g., Miller et al, 2008;Uhlenbrook et al, 2008;Cassiani et al, 2009) or, more relevant to the topic of the present work, monitoring the internal condition and temporal dynamics of geotechnical assets (e.g., Sjodahl et al, 2008, Wilkinson et al, 2011Chambers et al, 2014;Gunn et al, 2015a). Favored by the sensitivity of resistivity data to changing hydrogeological conditions, ERT, however, requires an additional stage of calibration, often site dependent, to invert for parameters more relevant to the mechanical description of the investigated target (e.g., moisture content, as in Cassiani et al, 2009;Chambers et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Time-lapse monitoring of fluid-induced geophysical property variations within an unstable earthwork using P-wave refraction

et al. 2016

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A significant portion of the UK's transportation system relies on a network of geotechnical earthworks (cuttings and embankments) that were constructed more than 100 years ago, whose stability is affected by the change in precipitation patterns experienced over the past few decades. The vulnerability of these structures requires a reliable, cost-and time-effective monitoring of their geomechanical condition. We have assessed the potential application of P-wave refraction for tracking the seasonal variations of seismic properties within an aged clay-filled railway embankment, located in southwest England. Seismic data were acquired repeatedly along the crest of the earthwork at regular time intervals, for a total period of 16 months. P-wave first-break times were picked from all available recorded traces, to obtain a set of hodocrones referenced to the same spatial locations, for various dates along the surveyed period of time. Traveltimes extracted from each acquisition were then compared to track the pattern of their temporal variability. The relevance of such variations over time was compared with the data experimental uncertainty. The multiple set of hodocrones was subsequently inverted using a tomographic approach, to retrieve a time-lapse model of V P for the embankment structure. To directly compare the reconstructed V P sections, identical initial models and spatial regularization were used for the inversion of all available data sets. A consistent temporal trend for P-wave traveltimes, and consequently for the reconstructed V P models, was identified. This pattern could be related to the seasonal distribution of precipitation and soil-water content measured on site.

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Section: Introductionmentioning

confidence: 99%

Time-lapse monitoring of fluid-induced geophysical property variations within an unstable earthwork using P-wave refraction

et al. 2016

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“…It is therefore crucial to develop efficient approaches for the assessment of earthwork stability, so that mitigation measures can be targeted and, consequently, failures can be avoided. Geophysical methods, when used as complementary tools together with traditional geotechnical investigations, are ideally suited for earthwork investigations (Donohue et al, 2011(Donohue et al, , 2012Chambers et al, 2014;Gunn et al, 2015a). In addition to being noninvasive, several techniques are cost effective and rapid, allowing detailed 2D and 3D volumetric information to be obtained, with repeated observations permitting temporal variations to be measured.…”

Section: Introductionmentioning

confidence: 99%

“…A recognized body of research is emerging, focusing on the relationship among electrical resistivity, moisture content, and pore pressure (Chambers et al, 2014;Gunn et al, 2015a); however, to date, little work has been carried out using seismic geophysical methods to temporally and spatially monitor variations in the mechanical properties of slopes. S-wave (V S ) and P-wave (V P ) seismic velocities are related to the small-strain shear modulus G 0 and constrained modulus M 0 as follows:…”

Section: Introductionmentioning

confidence: 99%

Time-lapse monitoring of climate effects on earthworks using surface waves

et al. 2016

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The UK's transportation network is supported by critical geotechnical assets (cuttings/embankments/dams) that require sustainable, cost-effective management, while maintaining an appropriate service level to meet social, economic, and environmental needs. Recent effects of extreme weather on these geotechnical assets have highlighted their vulnerability to climate variations. We have assessed the potential of surface wave data to portray the climate-related variations in mechanical properties of a clay-filled railway embankment. Seismic data were acquired bimonthly from July 2013 to November 2014 along the crest of a heritage railway embankment in southwest England. For each acquisition, the collected data were first processed to obtain a set of Rayleigh-wave dispersion and attenuation curves, referenced to the same spatial locations. These data were then analyzed to identify a coherent trend in their spatial and temporal variability. The relevance of the observed temporal variations was also verified with respect to the experimental data uncertainties. Finally, the surface wave dispersion data sets were inverted to reconstruct a time-lapse model of S-wave velocity for the embankment structure, using a least-squares laterally constrained inversion scheme. A key point of the inversion process was constituted by the estimation of a suitable initial model and the selection of adequate levels of spatial regularization. The initial model and the strength of spatial smoothing were then kept constant throughout the processing of all available data sets to ensure homogeneity of the procedure and comparability among the obtained V S sections. A continuous and coherent temporal pattern of surface wave data, and consequently of the reconstructed V S models, was identified. This pattern is related to the seasonal distribution of precipitation and soil water content measured on site.

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“…Also, while useful for ground truthing, the limited sampling of invasive site investigation (SI) methods makes them unsuitable for imaging irregular heterogeneous structures. Non-invasive geophysical techniques are cost-effective and rapid, and may provide twodimensional (2D) and three-dimensional (3D) information, which makes them ideal for studying the spatial and temporal variations within assets that cannot be readily captured using discrete boreholes or other forms of geotechnical investigation alone (Bergamo et al, 2016;Chambers et al, 2014;Gunn et al, 2015aGunn et al, , 2016.…”

Section: Embankment Characterisation and Imaging Usingmentioning

confidence: 99%

“…Geophysical imaging approaches can monitor internal property (condition) changes. These are the precursors connecting surface morphological response to subsurface processes driven by climate and ageing stresses (Gunn et al, 2015a(Gunn et al, , 2016. These property change signatures offer a potential baseline against which internal condition thresholds can be identified and used as early warning of future instability.…”

mentioning

confidence: 99%

Aged embankment imaging and assessment using surface waves

Gunn

Dashwood

Bergamo

et al. 2016

Proceedings of the Institution of Civil Engineers - Forensic En

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Rapid, non-intrusive surface wave surveys provide depth profiles from which ground models can be generated for use in earthwork condition assessment. Stiffness throughout earthworks controls the behaviour under static and dynamic loads, and characterising heterogeneity is of interest in relation to the stability of engineered backfill and life-cycle deterioration in aged utility and transportation infrastructure. Continuous surface wave methods were used to identify interfaces between fine-and coarse-grained fill in an end-tipped embankment along the Great Central Railway in Nottinghamshire, UK. Multichannel analysis of surface wave (MASW) methods were used to characterise subsurface voiding in a canal embankment along the Knottingley and Goole canal near Eggborough, Yorkshire. MASW methods are currently being used to study extreme weather impacts on the stability of a highplasticity clay embankment along the Gloucestershire-Warwickshire railway near Laverton. Optimal results were obtained using equipment capable of generating and detecting over wide frequency ranges. Notation

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Moisture monitoring in clay embankments using electrical resistivity tomography

Cited by 100 publications

References 20 publications

Time-lapse monitoring of fluid-induced geophysical property variations within an unstable earthwork using P-wave refraction

Time-lapse monitoring of fluid-induced geophysical property variations within an unstable earthwork using P-wave refraction

Time-lapse monitoring of climate effects on earthworks using surface waves

Aged embankment imaging and assessment using surface waves

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