dc.contributor.author | Ødegaard, Henki | |
dc.contributor.author | Nilsen, Bjørn | |
dc.date.accessioned | 2021-04-09T13:12:08Z | |
dc.date.available | 2021-04-09T13:12:08Z | |
dc.date.created | 2021-03-29T08:53:54Z | |
dc.date.issued | 2021 | |
dc.identifier.issn | 0723-2632 | |
dc.identifier.uri | https://hdl.handle.net/11250/2737166 | |
dc.description.abstract | To avoid hydraulic failure of unlined pressure tunnels, knowledge of minimum principal stress is needed. Such knowledge is only obtainable from in situ measurements, which are often time-consuming and relatively costly, effectively limiting the number of measurements typically performed. In an effort to enable more stress measurements, the authors propose a simplified and cost-effective stress measuring method; the Rapid Step-Rate Test (RSRT), which is based on existing hydraulic testing methods. To investigate the ability of this test to measure fracture normal stresses in field-like conditions, a true triaxial laboratory test rig has been developed. Hydraulic jacking experiments performed on four granite specimens, each containing a fracture, have been performed. Interpretation of pressure-, flow- and acoustic emission (AE) data has been used to interpret fracture behaviour and to assess fracture normal stresses. Our experimental data suggest that the proposed test method, to a satisfactory degree of reliability, can measure the magnitude of fracture normal stress. In addition, a clear correlation has been found between fracture closure and sudden increase in AE rate, suggesting that AE monitoring during testing can serve as a useful addition to the test. The rapid step-rate test is also considered relevant for field-scale measurements, with only minor adaptions. Our findings suggest that the RSRT can represent a way to get closer to the ideal of performing more testing along the entire length of pressure tunnel, and not only at key locations, which requires interpolation of stress data with varying degree of validity. | en_US |
dc.language.iso | eng | en_US |
dc.publisher | Springer | en_US |
dc.relation.uri | https://doi.org/10.1007/s00603-021-02452-9 | |
dc.rights | Navngivelse 4.0 Internasjonal | * |
dc.rights.uri | http://creativecommons.org/licenses/by/4.0/deed.no | * |
dc.subject | Bergmekanikk | en_US |
dc.subject | Rock mechanics | en_US |
dc.subject | Vannkraft | en_US |
dc.subject | Hydropower | en_US |
dc.title | Rock Stress Measurements for Unlined Pressure Tunnels: A True Triaxial Laboratory Experiment to Investigate the Ability of a Simplified Hydraulic Jacking Test to Assess Fracture Normal Stress | en_US |
dc.type | Peer reviewed | en_US |
dc.type | Journal article | en_US |
dc.description.version | publishedVersion | en_US |
dc.subject.nsi | VDP::Bergteknologi: 511 | en_US |
dc.subject.nsi | VDP::Mineral resources engineering: 511 | en_US |
dc.source.journal | Rock Mechanics and Rock Engineering | en_US |
dc.identifier.doi | 10.1007/s00603-021-02452-9 | |
dc.identifier.cristin | 1901550 | |
dc.relation.project | Norges forskningsråd: 257588 | en_US |
dc.description.localcode | © The Author(s) 2021.This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. | en_US |
cristin.ispublished | true | |
cristin.fulltext | original | |
cristin.qualitycode | 2 | |