Ultrasonic velocity survey in Callovo-Oxfordian argillaceous rock during shaft excavation

Balland, Cyrille; Morel, Jacques; Armand, Gilles; Pettitt, Will

doi:10.1016/j.ijrmms.2008.03.011

Cited by 22 publications

(7 citation statements)

References 19 publications

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“…Some have been determined by a direct measurement (Bemer et al, 2004;Escoffier, 2002;Homand et al, 2004) while others have been identified by back-calculation (Homand et al, 2006). lot of studies (Hoxha et al, 2007;Zhang and Rothfuchs, 2004), analysis of ultrasonic wave propagation across the rock media shows that a satisfactory model for argillite is a transverse isotropic one (Balland et al, 2009;David et al, 2007). In parallel, Ibrahim (2008) has analyzed data provided by micro-indentation based on a transverse isotropic model and has confirmed the stiffness anisotropy of Callovo-Oxfordian argillite.…”

Section: Origin Of the Study: Measurement Of Callovo-oxfordian Argillmentioning

confidence: 99%

An original constitutive law for Callovo-Oxfordian argillite, a two-scale double-porosity material

Cariou

Dormieux

Skoczylas

2013

Applied Clay Science

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Section: Origin Of the Study: Measurement Of Callovo-oxfordian Argillmentioning

confidence: 99%

An original constitutive law for Callovo-Oxfordian argillite, a two-scale double-porosity material

Cariou

Dormieux

Skoczylas

2013

Applied Clay Science

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“…The maximum investigation depth is close to 0.05 m for the maximum inter-sensor distance. The anisotropy of the P-wave velocity in the medium is transversal and does not exceed 10% (Balland et al, 2009). The influence of the anisotropy on the rays will therefore be 1.5% at most.…”

Section: Discussionmentioning

confidence: 93%

“…Tomographic images have already been obtained in underground structures in order to investigate the damaged zone (Maxwell and Young, 1996, Forney, 1999, Damaj et al 2007. In order to have a good resolution, however, it is necessary to deploy significant resources with a large number of sensors and boreholes (Balland et al, 2009). …”

Section: Introductionmentioning

confidence: 99%

High-resolution velocity field imaging around a borehole: Excavation-damaged zone characterization

Balland

Renaud

2009

GEOPHYSICS

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The excavation of a deep underground structure induces a stress field redistribution that creates an Excavation Damaged Zone (EDZ). Study of EDZ physical properties is of prime importance in the framework of nuclear waste geological storage, where EDZ constitutes a preferential pathway for storage materials towards the biosphere. Use of ultrasonic wave propagation inside the rock media is of great help as a near field non-intrusive technique for this. The significant research activity in the laboratory offers a large number of boreholes. These boreholes form linear excavations with a perfectly round section. It is for this reason that a specific probe and inversion method have been developed in order to reconstruct the image of the velocity field all around the environment of the boreholes. In order to recover all data needed with high accuracy and minimum effort, the probe is fully monitored for automatic data acquisition.This numerical inversion method has been preliminarily applied to a multi layer test bed in order to validate and optimise the experimental and numerical procedures. Based on those results, an in situ experiment has been performed in the Meuse/Haute-Marne Underground Research Laboratory (URL) in France for the safety assessment of nuclear waste storage in the Callovo-Oxfordian argillaceous layer.

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“…The extent of a damage zone depends on the type of host rock, the geomechanical conditions, and the excavation method ͑Barton, 2006͒. It may be as small as a few centimeters to as large as several shaft/tunnel radii, and its physical properties may vary over time; in argillaceous rocks, the hydraulic conductivities may decrease by orders of magnitude during the first few years after excavation as a result of various self-healing processes ͑Bossart et al., 2004;Blümling et al, 2007͒. In addition to recording microseismic and acoustic emissions ͑Falls and Young, 1998;Young et al, 2000;Young and Collins, 2001;Pettitt et al, 2002͒, various geoelectric ͑Kruschwitz andYaramanci, 2004;Gibert et al, 2006͒ and active ultrasonic ͑ 10 KHz͒ seismic methods ͑Falls and Young, 1998;Young and Collins, 2001;Schuster et al, 2001;Pettitt et al, 2002;Bastiaens et al, 2007;Damaj et al, 2007;Nicollin et al, 2008;Balland et al, 2009͒ have been used to monitor the evolution of EDZs based on data acquired within shafts/tunnels or within boreholes drilled from shafts/tunnels.…”

Section: Introductionmentioning

confidence: 99%

“…As a consequence, microseismicity and active seismic methods provide unique possibilities for remotely monitoring a repository in a largely nonintrusive manner. The principal differences between these methods and those employed from within a repository ͑Falls and Young, 1998;Young and Collins, 2001;Schuster et al, 2001;Pettitt et al, 2002;Bastiaens et al, 2007;Damaj et al, 2007;Nicollin et al, 2008;Balland et al, 2009͒ are the need to record seismic waves that have traveled over longer distances and the associated requirements to employ lower frequency sensors and ͑for the active methods͒ lower frequency more powerful energy sources.…”

Section: Introductionmentioning

confidence: 99%

Appraisal of waveform repeatability for crosshole and hole-to-tunnel seismic monitoring of radioactive waste repositories

et al. 2010

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Countries worldwide are seeking solutions for the permanent removal of high-level radioactive waste from the environment. Surrounding the waste with multiple engineered barriers and emplacement in deep geological repositories is widely accepted as a safe means of isolating it from the biosphere for the necessary 10 5 -10 6 years. As a precautionary measure, society demands that repositories be monitored for 100-300 years after they are backfilled and sealed. Effective monitoring that does not compromise the engineered and natural barriers is challenging. To address this issue, we investigate the viability of crosshole and hole-to-tunnel seismic methods for remotely monitoring high level radioactive waste repositories. Measurements are made at two underground rock laboratories in Switzerland, one within granitic rock and one within clay-rich sediments. Numerical simulations demonstrate that temporal changes of the monitored features ͑i.e., bentonite plug, excavation damage zone, sand-filled microtunnel͒ should produce significant changes in the seismic waveforms. Nevertheless, inversion for medium-property changes requires that true seismic waveform changes are not overwhelmed by recording variations. We find that a P-wave sparker source is highly repeatable up to frequencies of 3 -4 kHz for propagation distances out to tens of meters involved in repository-scale monitoring. Hydrophone repeatability is limited by incoherent high frequency noise and variable hydrophone-borehole coupling conditions, but firmly grouted geophones within the tunnels yield consistent recordings. Three kinds of coherent noise contaminate the data: ͑1͒ mechanically induced electrical effects in the hydrophone chains; ͑2͒ high currents in the sparker cable, which cause it to oscillate radially as a line source; and ͑3͒ tube waves. Our investigations outline a quantitative methodology to assess data-quality requirements for successful monitoring. We suggest that full waveform seismic tomography can be used to monitor radioactive waste emplacement tunnels, provided that careful attention is paid to instrument fidelity and noise suppression.

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Ultrasonic velocity survey in Callovo-Oxfordian argillaceous rock during shaft excavation

Cited by 22 publications

References 19 publications

An original constitutive law for Callovo-Oxfordian argillite, a two-scale double-porosity material

An original constitutive law for Callovo-Oxfordian argillite, a two-scale double-porosity material

High-resolution velocity field imaging around a borehole: Excavation-damaged zone characterization

Appraisal of waveform repeatability for crosshole and hole-to-tunnel seismic monitoring of radioactive waste repositories

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