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Pérez-Rey, I., Muñiz-Menéndez, M., Frühwirt, T., Konietzky, H., Jacobsson, L., Perras, M. A., . . . Alejano, L. R. (2024). Assessment of Direct Tensile Strength Tests in Rock Through a Multi-laboratory Benchmark Experiment. Rock Mechanics and Rock Engineering
Öppna denna publikation i ny flik eller fönster >>Assessment of Direct Tensile Strength Tests in Rock Through a Multi-laboratory Benchmark Experiment
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2024 (Engelska)Ingår i: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453XArtikel i tidskrift (Refereegranskat) Epub ahead of print
Abstract [en]

This study aims to experimentally assess repeatability and reproducibility of direct tensile strength (DTS) tests with deformability measurements on two types of rocks: Blanco Mera granite (Spain) and Cotta sandstone (Germany). The tests were conducted in four rock mechanics laboratories located in different countries (Canada, Germany, Spain and Sweden). A total of 51 tests were performed on cylindrical specimens of the two rocks, using different test equipment and measuring devices. Mean and standard deviation DTS values were determined in the four laboratories for the granite (5.70 ± 0.32, 6.06 ± 0.11, 3.84 ± 0.50 and 6.76 ± 0.10 MPa) and for the sandstone (1.88 ± 0.07, 1.96 ± 0.06, 1.15 ± 0.32 and 1.74 ± 0.19 MPa), together with Young’s moduli and Poisson’s ratios in tension, being statistically analysed to evaluate the variability and compare the main results obtained from the participating laboratories. The findings indicate that the DTS test with deformability measurements on cylindrical rock specimens is operationally feasible. However, certain shortcomings have been identified during the course of the experiments with the existing methodologies, such as the one suggested by the ISRM for DTS tests. The results have also shown to be sensitive to appropriate test and strain measurement configurations. The objective of this study was to shed light on these issues and provide new insights for potential future improvements of the existing testing methods.

Ort, förlag, år, upplaga, sidor
Springer Nature, 2024
Nyckelord
Direct tensile strength, Deformability, Reproducibility, Repeatability, Benchmark, Methodology
Nationell ämneskategori
Geoteknik
Identifikatorer
urn:nbn:se:ri:diva-72001 (URN)10.1007/s00603-023-03751-z (DOI)
Tillgänglig från: 2024-02-20 Skapad: 2024-02-20 Senast uppdaterad: 2024-02-22Bibliografiskt granskad
Godio, M. & Jacobsson, L. (2024). Experimental study on the hydromechanical behaviour of a natural unperturbed fracture under normal loading: Derivation of the equivalent hydraulic aperture and its digital reconstruction.
Öppna denna publikation i ny flik eller fönster >>Experimental study on the hydromechanical behaviour of a natural unperturbed fracture under normal loading: Derivation of the equivalent hydraulic aperture and its digital reconstruction
2024 (Engelska)Rapport (Övrigt vetenskapligt)
Abstract [en]

This report describes the laboratory work undertaken to characterize the hydromechanical behaviour of a natural rock fracture under varying normal loading. The hydraulic transmissivity of a granite specimen with a sealed (unopened) quasi-planar natural fracture of length 200 mm and width 200 mm was measured. The transmissivity measurements were conducted in the two perpendicular directions of the fracture, repeating them at five different normal compression stress levels, namely, ~0, 1, 2, 4, and 8 MPa, and flow gradients. The fracture was mechanically opened, and the measurements were repeated to investigate the effect of opening the fracture on its hydraulic transmissivity and hydromechanical behaviour. For one direction, the change in transmissivity was explored for high normal compression stress levels, up to ~40 MPa. Laminar flow conditions were ensured at every stage of the experimental campaign by working at very low Reynolds numbers (<1). The equivalent hydraulic aperture of the fracture was derived by resorting to the parallel-plate model theory. The hydraulic aperture was compared to the mechanical aperture, which was obtained by measuring the deformation of the specimen. In addition to the transmissivity tests, the geometry of the lateral walls and surfaces of the fracture was documented and measured by a series of tools, namely, digital scans, high-resolution pictures, optical readings by a stand microscope, and contact pressure-sheet measurements. The results achieved in this campaign shed light on the hydraulic transmissivity of sealed (unopened) and consequently opened natural fractures, and its dependency to the applied normal compression stress at low to very-low flow rates.

Förlag
s. 85
Serie
RISE Rapport ; 2024:8
Nyckelord
Natural rock fracture, Hydro-mechanical behaviour, Transmissivity, Normal load, Coupled stress-flow test, Laminar flow
Nationell ämneskategori
Materialteknik
Identifikatorer
urn:nbn:se:ri:diva-71540 (URN)978-91-89896-49-9 (ISBN)
Anmärkning

The experimental work was funded by Svensk Kärnbränslehantering AB (SKB) and is a part of the international project, TASK 10, of the SKB Task Force on Modelling of Groundwater Flow and Transport of Solutes (GWFTS) which involves several international nuclear waste management organisations.

Tillgänglig från: 2024-01-31 Skapad: 2024-01-31 Senast uppdaterad: 2024-01-31Bibliografiskt granskad
Jacobsson, L., Flansbjer, M. & Larsson, J. (2023). Direct shear tests on large natural and artificially induced rock fractures in a new laboratory equipment. In: Schubert, W. & Kluckner, A. (Ed.), Proceedings of the ISRM 15th International Congress on Rock Mechanics and Rock Engineering & 72nd Geomechanics Colloquium: Challenges in Rock Mechanics and Rock Engineering. Paper presented at ISRM 15th International Congress on Rock Mechanics and Rock Engineering & 72nd Geomechanics Colloquium, Salzburg, Austria, October 9-14, 2023 (pp. 2709-2714). Salzburg: Austrian Society for Geomechanics, Article ID 1827.
Öppna denna publikation i ny flik eller fönster >>Direct shear tests on large natural and artificially induced rock fractures in a new laboratory equipment
2023 (Engelska)Ingår i: Proceedings of the ISRM 15th International Congress on Rock Mechanics and Rock Engineering & 72nd Geomechanics Colloquium: Challenges in Rock Mechanics and Rock Engineering / [ed] Schubert, W. & Kluckner, A., Salzburg: Austrian Society for Geomechanics , 2023, s. 2709-2714, artikel-id 1827Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

A direct shear equipment for testing rock fractures up to 400×600 mm size, and up to 5 MN force in both normal and shear loading directions, was developed. Normal loading and direct shear tests under constant normal stiffness (CNS) and constant normal load (CNL) conditions were conducted on 300×500 mm specimens, one planar steel joint and two natural and two tensile induced rock fractures. Design targets, e.g. system to maintain undisturbed fractures up to testing and high system stiffnesses to achieve well-controlled shear tests, were verified by the experiments. A new optical system for local deformation measurements was used to accurately determine fracture displacements besides conventional non-local deformation measurements. The determined normal stiffnesses were similar previous results from the literature on smaller fractures, whereas the shear stiffness data are novel. The results provide a new insight into processes at the onset of fracture slip.

Ort, förlag, år, upplaga, sidor
Salzburg: Austrian Society for Geomechanics, 2023
Nyckelord
Rock fractures, large scale direct shear equipment, local optical deformation measurements, CNL, CNS, fracture stiffness
Nationell ämneskategori
Geoteknik
Identifikatorer
urn:nbn:se:ri:diva-67541 (URN)
Konferens
ISRM 15th International Congress on Rock Mechanics and Rock Engineering & 72nd Geomechanics Colloquium, Salzburg, Austria, October 9-14, 2023
Forskningsfinansiär
Svensk Kärnbränslehantering, SKB
Anmärkning

Funding of this work: SKB Svensk Kärnbränslehantering,  

NWMO Nuclear Waste Management Co https://www.nwmo.ca/ , 

BeFo Stiftelsen Bergteknisk Forskning https://www.befoonline.org/

Tillgänglig från: 2023-10-17 Skapad: 2023-10-17 Senast uppdaterad: 2023-10-17Bibliografiskt granskad
Hanquist, C., Jacobsson, L. & Davidsson, S. (2023). Laboratory tests in borehole KFM01A, KFM08A, KFM11A, KFR102A and KFR104: Uniaxial compression and indirect tensile strength tests of intact rock. Solna: Svensk Kärnbränslehantering AB
Öppna denna publikation i ny flik eller fönster >>Laboratory tests in borehole KFM01A, KFM08A, KFM11A, KFR102A and KFR104: Uniaxial compression and indirect tensile strength tests of intact rock
2023 (Engelska)Rapport (Övrigt vetenskapligt)
Abstract [en]

The density and mechanical properties were determined on water saturated specimens from boreholesKFM01A, KFM08A, KFM11A, KFR102A and KFR104 in the Forsmark site investigation area. Therock types in the selected sections were amphibolite (102017) and metavolcanic rock (103076). Somespecimens had a more or less foliated rock structure. The cores were sampled from a depth rangingbetween 196–901 m.The specimens were water saturated using tap water and all subsequent measurements wereconducted at this moisture condition. The density was determined on 30 specimens. The testingended with 20 indirect tensile tests yielding the indirect tensile strength and 10 uniaxial compressiontests including the post-peak response yielded the Young’s modulus, Poisson’s ratio and the uniaxialcompressive strength.Some variation of rock material along the short cores could be seen, which is reflected in themeasured data. The density at a water saturated condition was 2892–3067 kg/m3 for amphibolite, and2697–2763 kg/m3 for metavolcanic rock.The indirect tensile tests were conducted such that every specimen with visible foliation was testedwith the diametrical compression across the foliation planes, with higher values for the indirecttensile strength on the specimens. The strength variation in the amphibolite was large. The indirecttensile strength was 10.8–21.4 MPa for amphibolite and 16.9–20.7 MPa for metavolcanic rock. Twoof the amphibolite specimens had a deviating lower strength, indirect tensile strength 5.7 MParespectively 5.8 MPa, with a ductile failure. Those specimens had a high content of mica.The Young’s modulus obtained from the uniaxial compression tests was 88.6–114.5 GPa foramphibolite and 68.2–89.1 GPa for metavolcanic rock and the Poisson’s ratio was 0.339–0.386 foramphibolite and 0.236–0.313 for metavolcanic rock. The peak values of the axial compressive stresswere in the range 213.1–333.7 MPa for amphibolite and 104.1–283.1 MPa for metavolcanic rock.One of the amphibolite specimens had a deviating lower strength and a ductile failure with Young’smodulus 41.2 GPa, Poisson’s ratio 0.500 and peak axial compressive stress of 44.5 MPa. Thatspecimen had a high content of mica. 

Ort, förlag, år, upplaga, sidor
Solna: Svensk Kärnbränslehantering AB, 2023. s. 68
Serie
SKB P-23-05, ISSN 1651-4416
Nyckelord
Forsmark, elasticity parameters, post-failure behaviour, uniaxial compression test, indirect tensile test, AP SFK-22-032
Nationell ämneskategori
Geovetenskap och miljövetenskap
Identifikatorer
urn:nbn:se:ri:diva-67555 (URN)
Tillgänglig från: 2023-10-20 Skapad: 2023-10-20 Senast uppdaterad: 2024-03-03Bibliografiskt granskad
Jacobsson, L. & Godio, M. (2023). Measuring the hydraulic transmissivity of a rock joint under varying normal load. In: IOP Conference Series: Earth and Environmental Science. Paper presented at Eurock 2022 Symposium: Rock and Fracture Mechanics in Rock Engineering and Mining, 11 September 2022 through 15 September 2022. Institute of Physics (1)
Öppna denna publikation i ny flik eller fönster >>Measuring the hydraulic transmissivity of a rock joint under varying normal load
2023 (Engelska)Ingår i: IOP Conference Series: Earth and Environmental Science, Institute of Physics , 2023, nr 1Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

The water flow rate through a rectangular granite specimen with a tight unopened natural induced joint of dimensions 200×200 mm was measured in two perpendicular directions. The measurements were conducted at five different levels of stress corresponding to loading from 0 to 8 MPa and unloading back to 0 MPa. The flow was measured at different hydraulic gradients in the range of 10 to 25. The results showed a joint transmissivity between 0.002-0.03 mm2/s and a hydraulic aperture of 8-32 μm. It was shown that the measurements performed in the second orientation displayed smaller transmissivity and hydraulic aperture as compared to those in the first orientation, showing a residual compaction after the first load cycle. The Reynolds number was less than one in all the measurements yielding laminar flow conditions. Deviations from the linear regime relationship were observed for the lowest flow rates (Re &lt; 0.1). A transitory regime was observed when varying the hydraulic gradient. This regime was observed to be longer at the lowest flow rates. © 2023 Institute of Physics Publishing. All rights reserved.

Ort, förlag, år, upplaga, sidor
Institute of Physics, 2023
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:ri:diva-65344 (URN)10.1088/1755-1315/1124/1/012050 (DOI)2-s2.0-85146617420 (Scopus ID)
Konferens
Eurock 2022 Symposium: Rock and Fracture Mechanics in Rock Engineering and Mining, 11 September 2022 through 15 September 2022
Anmärkning

Funding details: TASK10; Funding text 1: The experimental work was funded by Swedish Nuclear Waste and Management Co, Sweden (SKB) and is a part of the international project, TASK10, on Groundwater Flow and Transport of Solutes (GWFTS) which involves several nuclear waste management companies.

Tillgänglig från: 2023-06-15 Skapad: 2023-06-15 Senast uppdaterad: 2023-06-15Bibliografiskt granskad
Arellanoa, S., Jacobsson, L., Kasani, B. & Steffen, H. (2022). EPOS Sweden: A national contribution to the European Plate Observing System-European Research Infrastructure Consortium. In: Abstract book: . Paper presented at Geological Society of Sweden 150 year anniversary meeting Uppsala, Sweden. August 17–19, 2022n.
Öppna denna publikation i ny flik eller fönster >>EPOS Sweden: A national contribution to the European Plate Observing System-European Research Infrastructure Consortium
2022 (Engelska)Ingår i: Abstract book, 2022Konferensbidrag, Poster (med eller utan abstract) (Övrigt vetenskapligt)
Abstract [en]

The pan-European “European Plate Observing System (EPOS)” is focussed on Europe and adjacent regions and includes geophysical monitoring networks, local observations (including permanent in-situ and volcano observatories), topographic/surface dynamics information, surface and subsurface geological information, experimental and laboratory data and functions, and satellite data. In 2021 the Swedish Research Council (VR) approved an application for Sweden to join EPOS-ERIC, formally establishing existing collaborations between EPOS and Swedish research infrastructures.

Nationell ämneskategori
Geologi
Identifikatorer
urn:nbn:se:ri:diva-60137 (URN)
Konferens
Geological Society of Sweden 150 year anniversary meeting Uppsala, Sweden. August 17–19, 2022n
Tillgänglig från: 2022-09-22 Skapad: 2022-09-22 Senast uppdaterad: 2024-02-21Bibliografiskt granskad
Jacobsson, L., Mas Ivars, D., Kasani, H. A. & Johansson, F. (2022). Experimental program to study scale effects on mechanical properties of large rock fractures. In: Abstract Volume: . Paper presented at Geological Society of Sweden 150 year anniversary meeting Uppsala, Sweden. August 17–19, 2022 (pp. 102-103).
Öppna denna publikation i ny flik eller fönster >>Experimental program to study scale effects on mechanical properties of large rock fractures
2022 (Engelska)Ingår i: Abstract Volume, 2022, s. 102-103Konferensbidrag, Muntlig presentation med publicerat abstract (Övrigt vetenskapligt)
Abstract [en]

The scale effect of natural and artifically induced rock fractures and replicas up to a 500 mm length are experimentally studied by direct shear tests in a testing program including a newly manufactured large shear testing equipment. The fractures are chatacterised pre-, syn-, and post-shear test. Combinations of different measurements provide a high-quality dataset enabling deeper understanding of, and constitutive model development for rock fractures used for safety assessment of deep geological respoitories for nuclear waste disposal.

Nationell ämneskategori
Geologi
Identifikatorer
urn:nbn:se:ri:diva-60139 (URN)
Konferens
Geological Society of Sweden 150 year anniversary meeting Uppsala, Sweden. August 17–19, 2022
Tillgänglig från: 2022-09-22 Skapad: 2022-09-22 Senast uppdaterad: 2024-02-21Bibliografiskt granskad
Kiuru, R., Jacobsson, L., Király, D. & Suikkanen, J. (2022). Geofysiikka louhintavauriotutkimuksissa. In: XXX Geofysiikan päivät: Helsingissä 18.‐19.5.2022. Paper presented at Geofysiikan päivät - Helsinki, Finland Duration: 18-19 May 2022 (pp. 34-35). Helsingfors: Geofysiikan Seura
Öppna denna publikation i ny flik eller fönster >>Geofysiikka louhintavauriotutkimuksissa
2022 (Finska)Ingår i: XXX Geofysiikan päivät: Helsingissä 18.‐19.5.2022, Helsingfors: Geofysiikan Seura , 2022, s. 34-35Konferensbidrag, Poster (med eller utan abstract) (Övrigt vetenskapligt)
Ort, förlag, år, upplaga, sidor
Helsingfors: Geofysiikan Seura, 2022
Serie
Geofysiikan päivät, E-ISSN 1798-2200 ; 30
Nationell ämneskategori
Geofysik
Identifikatorer
urn:nbn:se:ri:diva-72002 (URN)
Konferens
Geofysiikan päivät - Helsinki, Finland Duration: 18-19 May 2022
Tillgänglig från: 2024-02-20 Skapad: 2024-02-20 Senast uppdaterad: 2024-02-22Bibliografiskt granskad
Godio, M. & Jacobsson, L. (2022). Laboratory low-transmissivity tests on natural rock fracture under varying normal load. In: Programme of Geological Society of Sweden 150 year Anniversary meeting.: . Paper presented at Geological Society of Sweden 150 year Anniversary meeting. Uppsala, Sweden. August 17–19, 2022..
Öppna denna publikation i ny flik eller fönster >>Laboratory low-transmissivity tests on natural rock fracture under varying normal load
2022 (Engelska)Ingår i: Programme of Geological Society of Sweden 150 year Anniversary meeting., 2022Konferensbidrag, Poster (med eller utan abstract) (Övrigt vetenskapligt)
Abstract [en]

There is limited available data on natural rock fractures with low hydraulic transmissivity. In this study, we measured the transmissivity of a granite specimen with a 200×200 mm naturally-induced closed fracture under varying normal load. We repeated the measurements after opening the fracture to investigate how this affects its transmissivity. At each stage, we ensured laminar flows by setting Reynolds numbers << 1. Finally, we resorted to the parallel-plate theory to obtain the equivalent hydraulic aperture, that we compared to the mechanical aperture derived from the observed deformation.

Nationell ämneskategori
Energiteknik
Identifikatorer
urn:nbn:se:ri:diva-60138 (URN)
Konferens
Geological Society of Sweden 150 year Anniversary meeting. Uppsala, Sweden. August 17–19, 2022.
Tillgänglig från: 2022-09-22 Skapad: 2022-09-22 Senast uppdaterad: 2024-02-21Bibliografiskt granskad
Jacobsson, L. & Godio, M. (2022). Measuring the hydraulic transmissivity of a rock joint under varying normal load. In: : . Paper presented at EUROCK 2022 Rock and Fracture Mechanics in Rock Engineering and Mining - an ISRM Regional Symposium. Espoo, Finland. September 12-15, 2022..
Öppna denna publikation i ny flik eller fönster >>Measuring the hydraulic transmissivity of a rock joint under varying normal load
2022 (Engelska)Konferensbidrag, Muntlig presentation med publicerat abstract (Refereegranskat)
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:ri:diva-60212 (URN)
Konferens
EUROCK 2022 Rock and Fracture Mechanics in Rock Engineering and Mining - an ISRM Regional Symposium. Espoo, Finland. September 12-15, 2022.
Tillgänglig från: 2022-09-28 Skapad: 2022-09-28 Senast uppdaterad: 2023-05-25Bibliografiskt granskad
Organisationer
Identifikatorer
ORCID-id: ORCID iD iconorcid.org/0000-0003-4526-4061

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