In-situ stress amplification due to geological factors in tunnels: The case of Pajares tunnels, Spain

Geological and geomechanical anisotropies can significantly increase the magnitude of in-situ stress in a rock mass excavated for tunnelling purposes. Four tunnels for the new high-speed railway lines in Pajares in the Cantabrian Mountains, N. Spain, were analysed and significant deformations was fo...

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Detalles Bibliográficos
Autores: Hijazo Ramiro, Teresa, González De Vallejo González, Luis Ignacio
Tipo de recurso: artículo
Fecha de publicación:2012
País:España
Institución:Universidad Complutense de Madrid (UCM)
Repositorio:Docta Complutense
Idioma:inglés
OAI Identifier:oai:docta.ucm.es:20.500.14352/42188
Acceso en línea:https://hdl.handle.net/20.500.14352/42188
Access Level:acceso abierto
Palabra clave:551.4
In-situ stress
Tectonic stress
Structural stress
Stress amplification
Tunnel geology
Support design
Geodinámica
2507 Geofísica
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spelling In-situ stress amplification due to geological factors in tunnels: The case of Pajares tunnels, SpainHijazo Ramiro, TeresaGonzález De Vallejo González, Luis Ignacio551.4In-situ stressTectonic stressStructural stressStress amplificationTunnel geologySupport designGeodinámica2507 GeofísicaGeological and geomechanical anisotropies can significantly increase the magnitude of in-situ stress in a rock mass excavated for tunnelling purposes. Four tunnels for the new high-speed railway lines in Pajares in the Cantabrian Mountains, N. Spain, were analysed and significant deformations was found to have occurred in forty specific zones of these tunnels during excavation, requiring much more support than envisaged before construction. Local factors influencing in-situ stress have been identified in these zones of the tunnels, related to geological structures of high compressive tectonic stress regimes including thrust faults, folds with steep flank dip, orwith geomechanical anisotropies in contact zones between rock formations of different strengths. Amethodological procedurewas applied to four tunnels to assess the influence of the geological anisotropies on the insitu stress magnitudes. This procedure is based on the analysis of tunnel deformations and the support pressure needed to stabilise the excavations affected by geological anisotropies. The increase of in-situ stress due to local factors is expressed by the Stress Amplification Factor (SAF) defined by the ratio between the K(σH/σV)local value estimated in a particular rock mass tunnel zone and the mean K(σH/σV)regional value representative of the whole rock mass tunnel. Kregional was estimated from hydrofracture tests and from the TSI index. Klocal was calculated from the back analysis of the support pressure required to stabilise the deformed tunnel zones. SAF values for the forty specific tunnel zones ranged from 1.1 to 2.5. This significant increase in the magnitude of in-situ stress emphasises the influence of geological and geomechanical anisotropies in tunnel stability and support design. The results provide a quantitative approach for assessing structural stresses in rock masses for tunnelling excavations.ElsevierUniversidad Complutense de Madrid20122012-01-0120122012-01-01journal articlehttp://purl.org/coar/resource_type/c_6501info:eu-repo/semantics/articleapplication/pdfhttps://hdl.handle.net/20.500.14352/42188reponame:Docta Complutenseinstname:Universidad Complutense de Madrid (UCM)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2info:eu-repo/semantics/openAccessoai:docta.ucm.es:20.500.14352/421882026-06-02T12:44:21Z
dc.title.none.fl_str_mv In-situ stress amplification due to geological factors in tunnels: The case of Pajares tunnels, Spain
title In-situ stress amplification due to geological factors in tunnels: The case of Pajares tunnels, Spain
spellingShingle In-situ stress amplification due to geological factors in tunnels: The case of Pajares tunnels, Spain
Hijazo Ramiro, Teresa
551.4
In-situ stress
Tectonic stress
Structural stress
Stress amplification
Tunnel geology
Support design
Geodinámica
2507 Geofísica
title_short In-situ stress amplification due to geological factors in tunnels: The case of Pajares tunnels, Spain
title_full In-situ stress amplification due to geological factors in tunnels: The case of Pajares tunnels, Spain
title_fullStr In-situ stress amplification due to geological factors in tunnels: The case of Pajares tunnels, Spain
title_full_unstemmed In-situ stress amplification due to geological factors in tunnels: The case of Pajares tunnels, Spain
title_sort In-situ stress amplification due to geological factors in tunnels: The case of Pajares tunnels, Spain
dc.creator.none.fl_str_mv Hijazo Ramiro, Teresa
González De Vallejo González, Luis Ignacio
author Hijazo Ramiro, Teresa
author_facet Hijazo Ramiro, Teresa
González De Vallejo González, Luis Ignacio
author_role author
author2 González De Vallejo González, Luis Ignacio
author2_role author
dc.contributor.none.fl_str_mv Universidad Complutense de Madrid
dc.subject.none.fl_str_mv 551.4
In-situ stress
Tectonic stress
Structural stress
Stress amplification
Tunnel geology
Support design
Geodinámica
2507 Geofísica
topic 551.4
In-situ stress
Tectonic stress
Structural stress
Stress amplification
Tunnel geology
Support design
Geodinámica
2507 Geofísica
description Geological and geomechanical anisotropies can significantly increase the magnitude of in-situ stress in a rock mass excavated for tunnelling purposes. Four tunnels for the new high-speed railway lines in Pajares in the Cantabrian Mountains, N. Spain, were analysed and significant deformations was found to have occurred in forty specific zones of these tunnels during excavation, requiring much more support than envisaged before construction. Local factors influencing in-situ stress have been identified in these zones of the tunnels, related to geological structures of high compressive tectonic stress regimes including thrust faults, folds with steep flank dip, orwith geomechanical anisotropies in contact zones between rock formations of different strengths. Amethodological procedurewas applied to four tunnels to assess the influence of the geological anisotropies on the insitu stress magnitudes. This procedure is based on the analysis of tunnel deformations and the support pressure needed to stabilise the excavations affected by geological anisotropies. The increase of in-situ stress due to local factors is expressed by the Stress Amplification Factor (SAF) defined by the ratio between the K(σH/σV)local value estimated in a particular rock mass tunnel zone and the mean K(σH/σV)regional value representative of the whole rock mass tunnel. Kregional was estimated from hydrofracture tests and from the TSI index. Klocal was calculated from the back analysis of the support pressure required to stabilise the deformed tunnel zones. SAF values for the forty specific tunnel zones ranged from 1.1 to 2.5. This significant increase in the magnitude of in-situ stress emphasises the influence of geological and geomechanical anisotropies in tunnel stability and support design. The results provide a quantitative approach for assessing structural stresses in rock masses for tunnelling excavations.
publishDate 2012
dc.date.none.fl_str_mv 2012
2012-01-01
2012
2012-01-01
dc.type.none.fl_str_mv journal article
http://purl.org/coar/resource_type/c_6501
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://hdl.handle.net/20.500.14352/42188
url https://hdl.handle.net/20.500.14352/42188
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Elsevier
publisher.none.fl_str_mv Elsevier
dc.source.none.fl_str_mv reponame:Docta Complutense
instname:Universidad Complutense de Madrid (UCM)
instname_str Universidad Complutense de Madrid (UCM)
reponame_str Docta Complutense
collection Docta Complutense
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15.301603

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