| 1. |
- Andersson, J. C., et al.
(författare)
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Modeling the Äspö Pillar stability experiment
- 2010
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Ingår i: Rock Mechanics in Civil and Environmental Engineering - Proceedings of the European Rock Mechanics Symposium, EUROCK 2010. - 9780415586542 ; , s. 787-790
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Konferensbidrag (refereegranskat)abstract
- This paper presents results of the 1st stages ofTaskAof the Decovalex 2011 project, the numerical modeling of the Äspö Pillar Stability experiment performed by the Äspö Hard Rock Laboratory of the Swedish Nuclear Fuel and Waste Management Company (SKB). The objective is to perform back calculation of the Äspö pillar behavior using state of the art numerical modeling techniques for the material behavior. The work is divided into three stages and it is the first stage of thework that will be presented in this paper. Seven international teams from six different countries participated in the task and contributed to the results presented in this paper, concerning back calculation of uniaxial and triaxial compressive core testing and elastic back calculation of the stress path for excavation-induced stresses. The results are useful for understanding the occurrence of spalling in the upper part of the pillar during excavation and the stress path modeling gives the first approximation of the yielding strength of the pillar. The calculated results agree well with observations measured during experiment.
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| 2. |
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| 3. |
- Hudson, John A., et al.
(författare)
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Characterising and modelling the excavation damaged zone in crystalline rock in the context of radioactive waste disposal
- 2009
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Ingår i: Environmental Geology. - : Springer Science and Business Media LLC. - 0943-0105 .- 1432-0495. ; 57:6, s. 1275-1297
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes current knowledge about the nature of and potential for thermo-hydro-mechanical-chemical modelling of the excavation damaged zone (EDZ) around the excavations for an underground radioactive waste repository. In the first part of the paper, the disturbances associated with excavation are explained, together with reviews of Workshops that have been held on the subject. In the second part of the paper, the results of a DECOVALEX [DEmonstration of COupled models and their VALidation against EXperiment: research funded by an international consortium of radioactive waste regulators and implementers (http://www.decovalex.com)] research programme on modelling the EDZ are presented. Four research teams used four different models to simulate the complete stress-strain curve for Avro granite from the Swedish A"spo Hard Rock Laboratory. Subsequent research extended the work to computer simulation of the evolution of the repository using a 'wall-block model' and a 'near-field model'. This included assessing the evolution of stress, failure and permeability and time-dependent effects during repository evolution. As discussed, all the computer models are well suited to sensitivity studies for evaluating the influence of their respective supporting parameters on the complete stress-strain curve for rock and for modelling the EDZ.
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| 4. |
- Huertas-Hernando, D., et al.
(författare)
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Hydro power flexibility for power systems with variable renewable energy sources : An IEA Task 25 collaboration
- 2016
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Ingår i: Wiley Interdisciplinary Reviews. - : John Wiley & Sons. - 2041-8396 .- 2041-840X.
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Tidskriftsartikel (refereegranskat)abstract
- Hydro power is one of the most flexible sources of electricity production. Power systems with considerable amounts of flexible hydro power potentially offer easier integration of variable generation, e.g., wind and solar. However, there exist operational constraints to ensure mid-/long-term security of supply while keeping river flows and reservoirs levels within permitted limits. In order to properly assess the effective available hydro power flexibility and its value for storage, a detailed assessment of hydro power is essential. Due to the inherent uncertainty of the weather-dependent hydrological cycle, regulation constraints on the hydro system, and uncertainty of internal load as well as variable generation (wind and solar), this assessment is complex. Hence, it requires proper modeling of all the underlying interactions between hydro power and the power system, with a large share of other variable renewables. A summary of existing experience of wind integration in hydro-dominated power systems clearly points to strict simulation methodologies. Recommendations include requirements for techno-economic models to correctly assess strategies for hydro power and pumped storage dispatch. These models are based not only on seasonal water inflow variations but also on variable generation, and all these are in time horizons from very short term up to multiple years, depending on the studied system. Another important recommendation is to include a geographically detailed description of hydro power systems, rivers' flows, and reservoirs as well as grid topology and congestion.
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| 5. |
- Uotinen, L. K. T., et al.
(författare)
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A method to downscale joint surface roughness and to create replica series using 3D printed molds
- 2017
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Ingår i: 13th ISRM International Congress of Rock Mechanics. - : International Society for Rock Mechanics. - 9781926872254
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Konferensbidrag (refereegranskat)abstract
- In order to determine the in-situ shear strength of rock joints, large scale testing is required. However, this is both expensive and difficult to execute. One possible method to overcome this may be to use photogrammetry to capture large joint surface roughness in-situ and downscale it to replica samples, which could be sheared in laboratory. In this paper, as a first part in such a method, a technique to digitize surface roughness and to produce replica samples for laboratory shear testing from a larger joint sample are presented. First, a thin granitic rock slice with dimensions of 1.75 m x 0.95 m of granitic intact rock was chosen for the study. The joint surface is fresh and created through tensile induced splitting. The large joint sample is digitized using photogrammetry. Then, one fullscale 1.7 m x 0.6 m geometry is cropped from the digitized joint geometry and then subsamples at 10x, 7.5x, 5x, 2.5x and 1x scales. All sub-geometries are scaled down digitally to produce 0.17 m by 0.06 m geometries. The geometries are used to make casting molds both positive and negative to produce samples with perfect matedness. The casting molds are 3D printed in polylactic acid plastic and C60/75 concrete is cast to produce a replica series. In addition to the creation of this replica series, two pilot replicas are also tested using a portable shear box with a 0.5 MPa normal pressure. The results from the pilot rounds are presented and discussed. Finally, suggestions for future research are given.
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