Baillet, L.

Colombero, C.

Comina, C.

Jongmans, D.

Vinciguerra, S.

English

Colombero C.

Baillet L.

Comina C.

Jongmans D.

Vinciguerra S.

PORTO@iris (Publications Open Repository TOrino - Politecnico di Torino)

04 August 2020POLITECNICO DI TORINORepository ISTITUZIONALEActive and passive seismic methods for characterization and monitoring of unstable rock masses: field surveys,laboratory tests and modeling / Colombero, C.; Baillet, L.; Comina, C.; Jongmans, D.; Vinciguerra, S.. - In:GEOPHYSICAL RESEARCH ABSTRACTS. - ISSN 1607-7962. - 18(2016), p. EGU2016-7513. ((Intervento presentato alconvegno EGU General Assembly 2016 tenutosi a Vienna (Austria) nel 17-22 April 2016.OriginalActive and passive seismic methods for characterization and monitoring of unstable rock masses: fieldsurveys, laboratory tests and modelingPublisher:PublishedDOI:Terms of use:openAccessPublisher copyright(Article begins on next page)This article is made available under terms and conditions as specified in the  corresponding bibliographic description inthe repositoryAvailability:This version is available at: 11583/2746550 since: 2019-08-07T10:40:42ZCopernicus GmbHGeophysical Research AbstractsVol. 18, EGU2016-7513, 2016EGU General Assembly 2016© Author(s) 2016. CC Attribution 3.0 License.Active and passive seismic methods for characterization and monitoringof unstable rock masses: field surveys, laboratory tests and modeling.Chiara Colombero (1), Laurent Baillet (2), Cesare Comina (1), Denis Jongmans (2), Sergio Vinciguerra (1,3)(1) Dipartimento di Scienze della Terra, Universita’ di Torino, , (2) Université Grenoble Alpes, ISTerre, CNRS, (3) BritishGeological Survey, Leicester, United KingdomAppropriate characterization and monitoring of potentially unstable rock masses may provide a better knowledgeof the active processes and help to forecast the evolution to failure. Among the available geophysical methods,active seismic surveys are often suitable to infer the internal structure and the fracturing conditions of the unstablebody. For monitoring purposes, although remote-sensing techniques and in-situ geotechnical measurements aresuccessfully tested on landslides, they may not be suitable to early forecast sudden rapid rockslides. Passiveseismic monitoring can help for this purpose. Detection, classification and localization of microseismic eventswithin the prone-to-fall rock mass can provide information about the incipient failure of internal rock bridges.Acceleration to failure can be detected from an increasing microseismic event rate. The latter can be comparedwith meteorological data to understand the external factors controlling stability. On the other hand, seismic noiserecorded on prone-to-fall rock slopes shows that the temporal variations in spectral content and correlation ofambient vibrations can be related to both reversible and irreversible changes within the rock mass.We present the results of the active and passive seismic data acquired at the potentially unstable granitic cliff ofMadonna del Sasso (NW Italy).Down-hole tests, surface refraction and cross-hole tomography were carried out for the characterization of thefracturing state of the site. Field surveys were implemented with laboratory determination of physico-mechanicalproperties on rock samples and measurements of the ultrasonic pulse velocity. This multi-scale approach led to alithological interpretation of the seismic velocity field obtained at the site and to a systematic correlation of themeasured velocities with physical properties (density and porosity) and macroscopic features of the granitic cliff(fracturing, weathering and anisotropy).Continuous passive seismic monitoring at the site, from October 2013 to present, systematically highlighted clearenergy peaks in the spectral content of seismic noise on the unstable sector, interpreted as resonant frequencies ofthe investigated volume. Both spectral analysis and cross-correlation of seismic noise showed seasonal reversiblevariation trends related to air temperature fluctuations. No irreversible changes, resulting from serious damageprocesses within the rock mass, were detected so far.Modal analysis and geomechanical modeling of the unstable cliff are currently under investigation to betterunderstand the vibration modes that could explain the measured amplitude and orientation of ground motion at thefirst resonant frequencies.Classification and location of microseismic events still remains the most challenging task, due to the complexstructural and morphological setting of the site.

Active and passive seismic methods for characterization and monitoring of unstable rock masses: field surveys, laboratory tests and modeling

https://iris.polito.it/retrieve/handle/11583/2746550/264456/EGU2016-7513.pdf

Active and passive seismic methods for characterization and monitoring of unstable rock masses: field surveys, laboratory tests and modeling

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