Photogrammetric prediction of rock fracture properties and validation with metric shear tests

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2021-07
Major/Subject
Mcode
Degree programme
Language
en
Pages
31
Series
Geosciences (Switzerland), Volume 11, issue 7
Abstract
An accurate understanding of jointed rock mass behavior is important in many applications ranging from deep geological disposal of nuclear waste, to deep mining, and to urban geoengineering projects. The roughness of rock fractures and the matching of the fracture surfaces are the key contributors to the shear strength of rock fractures. In this research, push shear tests with three normal stress levels of 3.6, 6.0, and 8.5 kPa were conducted on two granite samples with artificially induced well-matching tensile fractures with sizes of 500 mm x 250 mm and 1000 mm x 500 mm. The large sample reached on average a -60% weaker peak shear stress than the medium-sized sample, and a strong negative scale effect was observed in the peak shear strength. The roughness of the surfaces was measured using a profilometer and photogrammetry. The scale-corrected profilometer-based method (joint roughness coefficient, JRC) underestimates the peak friction angle for the medium-sized slabs by -27% for the medium sample and -9% for the large sample. The photogrammetry-based (Z'(2)) method produces an estimate with -7% (medium) and + 12% (large) errors. The photogrammetry-based Z'(2) is an objective method that consistently produces usable estimates for the JRC and peak friction angle.
Description
Funding Information: This work was made possible thanks to the funding provided by the State Nuclear Waste Management Fund (VYR) and the support of the Finnish Ministry of Economic Affairs and Employment on the Finnish Research Programme on Nuclear Waste Management KYT2018 and KYT2022 of the Nuclear Energy Act (990/1987) in the research projects Mechanical Properties of Rock Joints (KARMO) and Fluid flow in fractured hard rock mass (RAKKA). Funding Information: Funding: This work was made possible thanks to the funding provided by the State Nuclear Waste Management Fund (VYR) and the support of the Finnish Ministry of Economic Affairs and Employ‐ ment on the Finnish Research Programme on Nuclear Waste Management KYT2018 and KYT2022 of the Nuclear Energy Act (990/1987) in the research projects Mechanical Properties of Rock Joints (KARMO) and Fluid flow in fractured hard rock mass (RAKKA). Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Keywords
Friction angle, Photogrammetry, Roughness, Scale effect, Shear test
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Citation
Uotinen , L , Torkan , M , Baghbanan , A , Hernández , E C & Rinne , M 2021 , ' Photogrammetric prediction of rock fracture properties and validation with metric shear tests ' , Geosciences (Switzerland) , vol. 11 , no. 7 , 293 . https://doi.org/10.3390/geosciences11070293