Statistical pre-processing and analyses of hydro-meteorological time series in a geologic clay site (methodology and first results for Mont Terri’s PP experiment)

Fatmi, H.A.; Ababou, Rachid; Matray, Jean-Michel

doi:10.1016/j.pce.2008.10.052

Cited by 5 publications

(6 citation statements)

References 6 publications

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“…Previous pre-processed methods were proposed by Fatmi et al (2008) and by Fatmi (2009). The procedure developed in Bailly et al (2012a) is employed in this study and implemented with the MUSTAT preprocessing Tool Box.…”

Section: Time Series Pre-processing Stepmentioning

confidence: 99%

“…correlation function (note that R xx (0) = 1), D j = D(τ j ), Eq. (6b), is a spectral filter (the Tukey filter defined in Fatmi et al (2008) and Fatmi (2009)), and f i is the discrete positive dimensional frequency [Hz]:…”

Section: Auto-spectrum Of a Signal X(t N )mentioning

confidence: 99%

“…This is true for continuous as well as discrete multi-resolution wavelets. Concerning the use of wavelets in the context of interest in this paper (time response of a geologic repository for radioactive waste), let us mention that multi-resolution discrete wavelets (rather than continuous wavelets) were used by Fatmi et al (2008), Fatmi (2009), Fatmi et al (2011 and Ababou et al (2012), to identify rock properties from semi-diurnal earth tides, and to quantify the effect of tunnel excavation on semi-diurnal pore pressure fluctuations at different stages (pre-, syn-, and post-excavation). This study led to conclusions on the evolution of rock properties near an advancing excavation front at the Mont Terri URL site (Switzerland).…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…For more details, see Fatmi et al (2008) and Bailly et al (2012a). The "clean" signals (pre-processed data) are then synchronized and stored into a global rectangular matrix containing the time column plus all signals as column vectors.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Temporal behavior of a ventilated claystone at the Tournemire URL: Cross-spectral analyses focused on daily harmonics

Bailly

Matray

Ababou

2014

Engineering Geology

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Section: Time Series Pre-processing Stepmentioning

confidence: 99%

Section: Auto-spectrum Of a Signal X(t N )mentioning

confidence: 99%

Section: Acknowledgmentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Temporal behavior of a ventilated claystone at the Tournemire URL: Cross-spectral analyses focused on daily harmonics

Bailly

Matray

Ababou

2014

Engineering Geology

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“…External boundary radius [m] 0-5 K stands for hydraulic conductivity and Ss for specific storage. Skin zone conductivity ranges were set one order of magnitude higher compared to intact rock Radioprotection et de Sûreté Nucléaire and the Institut National Polytechnique de Toulouse (Fatmi et al 2008;Ababou et al 2012;Bailly et al 2014). Consisting in a Python code associated with toolboxes programmed in Matlab, the package provides automatic features: (a) preprocessing of time series, that enables the detection of time gaps and spurious values, as well as data reconstruction by autoregressive first order process; (b) processing of a single time series; (c) cross-analysis of two time series.…”

Section: Tidal Analysis On Pore Pressure Time Seriesmentioning

confidence: 99%

Comparative study of methods to estimate hydraulic parameters in the hydraulically undisturbed Opalinus Clay (Switzerland)

Matray

Gonçalvès

et al. 2017

Swiss J Geosci

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International audienceThe deep borehole (DB) experiment gave the opportunity to acquire hydraulic parameters in a hydraulically undisturbed zone of the Opalinus Clay at the Mont Terri rock laboratory (Switzerland). Three methods were used to estimate hydraulic conductivity and specific storage values of the Opalinus Clay formation and its bounding formations through the 248 m deep borehole BDB-1: application of a Poiseuille-type law involving petrophysical measurements, spectral analysis of pressure time series and in situ hydraulic tests. The hydraulic conductivity range in the Opalinus Clay given by the first method is 2 × 10−14–6 × 10−13 m s−1 for a cementation factor ranging between 2 and 3. These results show low vertical variability whereas in situ hydraulic tests suggest higher values up to 7 × 10−12 m s−1. Core analysis provides economical estimates of the homogeneous matrix hydraulic properties but do not account for heterogeneities at larger scale such as potential tectonic conductive features. Specific storage values obtained by spectral analysis are consistent and in the order of 10−6 m−1, while formulations using phase shift and gain between pore pressure signals were found to be inappropriate to evaluate hydraulic conductivity in the Opalinus Clay. The values obtained are globally in good agreement with the ones obtained previously at the rock laboratory

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A multi-scalar study of the long-term reactivity of uranium mill tailings from Bellezane site (France)

Ballini

Chautard

Nos

et al. 2020

Journal of Environmental Radioactivity

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The mill tailings from uranium mines constitute very low-level, long-lived, radioactive process waste. Their longterm management therefore requires a good understanding of the geochemical mechanisms regulating the mobility of residual U and 226 Ra. This article presents the results of the detailed characterization of the tailings resulting from the dynamic leaching processes used on the ore of the La Crouzille mining division and stored at the Bellezane site (Haute-Vienne, France) for over 25 years. A multi-scalar and multidisciplinary approach was developed based on a study of the site's history, on the chemical, radiological and mineralogical characterizations of the solid fraction of the tailings, and on porewater analyses. These were supplemented by thermodynamic equilibrium models to predict the long-term mobility of U and 226 Ra. Weakly acidic (pH = 6.35) and oxidizing (Eh = 138 mV/SHE) porewaters had a sulfated-magnesian facies ([SO4]tot = 43 mmol/L ; [Mg]tot = 33 mmol/L) with an accessory calcium bicarbonate component (TIC = 25 mmol/L ; [Ca]tot = 13 mmol/L) and dissolved concentrations of uranium and 226 Ra of 12x10-6 mol/L and 0.58 Bq/L respectively. Ultra-filtration at 10 kDa indicated the absence of colloidal phases. The characterization of the tailings confirmed their homogeneity from a radiological, chemical and mineralogical point of view. The residual U and 226 Ra concentrations measured in the solid were 160 ppm and 25 Bq/g respectively, in accordance with the initial ore grades and mill yields, or more than 99% of the total stock. In terms of chemical and mineralogical composition, the tailings were mainly composed of minerals from the granitic ore (quartz, potassium feldspar, plagioclases and micas) in association with their weathering products (smectite and ferric oxyhydroxides) and with neo-formed minerals following rapid diagenesis after neutralization of the tailings before their emplacement (gypsum and barite). All these minerals are effective traps for the retention of U and 226 Ra. The uranium is distributed partly in micrometer scale uraninite and coffinite refractory phases embedded in grains of quartz, and partly sorbed to smectite and ferric oxyhydroxides. The 226 Ra on the other hand is trapped mainly within the barite. The aqueous concentrations of U and 226 Ra could be described using a thermodynamic approach so that their long-term mobility can subsequently be assessed by modeling. The paragenesis of the tailings could be seen to be stable over time with the exception of neo-formed gypsum and calcite, which will gradually dissolve. The presence of retention traps offering surplus capacity, i.e. smectite, ferric oxyhydroxides and barite, will maintain the U and the 226 Ra at very low aqueous concentrations, even under oxidizing conditions. Moreover, the low permeability of the mill tailings leads, in the case of 226 Ra, to behavior dictated only by the radioactive decay. Highlights (no more than 85 characters, including spaces)  U mill tailings from Bellezane (France) were studied...

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Statistical pre-processing and analyses of hydro-meteorological time series in a geologic clay site (methodology and first results for Mont Terri’s PP experiment)

Cited by 5 publications

References 6 publications

Temporal behavior of a ventilated claystone at the Tournemire URL: Cross-spectral analyses focused on daily harmonics

Temporal behavior of a ventilated claystone at the Tournemire URL: Cross-spectral analyses focused on daily harmonics

Comparative study of methods to estimate hydraulic parameters in the hydraulically undisturbed Opalinus Clay (Switzerland)

A multi-scalar study of the long-term reactivity of uranium mill tailings from Bellezane site (France)

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