| 1. |
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| 2. |
- Feng, Q., et al.
(författare)
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Measuring fracture orientation at exposed rock faces by using a non-reflector total station
- 2001
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Ingår i: Engineering Geology. - 0013-7952 .- 1872-6917. ; 59:1-2, s. 133-146
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of fracture orientation are usually taken by using a compass-inclinometer device on exposed rock faces. The drawbacks when using this method is that it is time-consuming if many fractures are measured and that measurement might be impossible if the rock face cannot be safely reached physically. To improve field mapping of rock fractures, a method for applying a non-reflector total station to measuring fracture orientation is presented in this paper. A non-reflector total station is a geodetic device that captures three-dimensional co-ordinates of target points without using a reflector. Therefore, physical touching the rock surfaces is no longer required. To determine a fracture orientation, co-ordinates of a set of points on the exposed fracture surface are captured at a distance from the rock face. The best-fit plane of the exposed fracture surface is defined by the co-ordinates of the target points, and the orientation (e.g. dip angle and dip direction) of the fracture surface is determined as that of its best-fit plane. This paper presents the technical procedure and a portable system designed for the field mapping of fracture orientation. Results of a case study performed at an exposed rock face are also included.
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| 3. |
- Mörner, Nils-Axel, 1938-
(författare)
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In absurdum : long-term predictions and nuclear waste handling
- 2001
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Ingår i: Engineering Geology. - 0013-7952 .- 1872-6917. ; 61:2-3, s. 75-82
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Tidskriftsartikel (refereegranskat)abstract
- Careful use of scientific knowledge allows predictions into the future. When the time units for our predictions increases to hundreds of thousands of years, we have extended our abilities 'in absurdum'. This is true for long-term safety statements regarding the handling of our high-level nuclear waste. The Fennoscandian Shield has been claimed to offer exceptionally stable bedrock conditions over immense time periods. We only need to go back to the last deglacial phase some 10,000 years ago to have a totally different situation from that of today. At that time Sweden was characterized by exceptionally high seismic activity; both in amplitude and frequency. These conditions (like a number of related phenomena) will be repeated at future lee Ages. In such an environment, there can be no safe repository in the bedrock. In the absence of true long-term safety, we can only recommend the utilization of the Dry Rock Deposit (DRD) method where the waste is stored in the bedrock under dry conditions, under constant control and monitoring, accessible for maintenance and possible future methods of rendering the waste harmless and even removal. (C) 2001 Elsevier Science B.V. All rights reserved.
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| 4. |
- Langer, M., et al.
(författare)
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Editors introduction to special issue on geosciences and nuclear waste isolation.
- 2001
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Ingår i: Engineering Geology. - 0013-7952. ; 61, s. 69-73
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Crustal roots formed beneath mountain belts are gravitationally unstable structures, which rebound when the lateral forces that created them cease or decrease significantly relative to gravity. Crustal roots do not rebound as a rigid body, but undergo int
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| 5. |
- Liu, Hongyuan, et al.
(författare)
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Characterization of rock heterogeneity and numerical verification
- 2004
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Ingår i: Engineering Geology. - : Elsevier BV. - 0013-7952 .- 1872-6917. ; 72:1, s. 89-119
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Tidskriftsartikel (refereegranskat)abstract
- On the basis of microstructure analysis and image analysis, rock heterogeneity is modelled by the rock and tool (R-T2D) interaction code according to homogenisation theory. The simulated results predict very well the non-linear stress–strain behaviour and the progressive fracture process of heterogeneous rock material. It is found that the weak parts and subsequent fractures before localization represent an obvious statistically uniform characteristic. Therefore, a statistical method is used to model rock heterogeneity. The results from the statistical modelling are in surprisingly good agreement with those from the homogenisation modelling. Considering the research scale, the rock heterogeneity is characterized better by the Weibull statistical method as a few characteristic parameters: the homogeneous index and the elemental seed parameters of the R-T2D finite element network. Finally, a series of numerical experiments are conducted to validate that the characterization of rock heterogeneity is reasonable and feasible, and that the R-T2D code is stable, repeatable and a valuable tool to research the fracture process of heterogeneous material.
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| 6. |
- Talbot, CJ, et al.
(författare)
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Stress control of hydraulic conductivity in fracture-saturated Swedish bedrock
- 2001
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Ingår i: ENGINEERING GEOLOGY. - : ELSEVIER SCIENCE BV. - 0013-7952. ; 61:2-3, s. 145-153
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Tidskriftsartikel (refereegranskat)abstract
- The granitoid bedrock exposed in the Aspo Hard Rock Laboratory is the best known rock mass in Sweden but is probably generally similar to most of the country in many characteristics relevant to the long term isolation of spent nuclear fuel. Like most Prec
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| 7. |
- Åkesson, Urban, 1972, et al.
(författare)
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Characterisation of microcracks in the Bohus granite, western Sweden, caused by uniaxial cyclic loading
- 2004
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Ingår i: Engineering Geology. - : Elsevier BV. - 0013-7952. ; 72:1-2, s. 131-142
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Tidskriftsartikel (refereegranskat)abstract
- Microcracking is highly dependent on the mineralogy, fabric, and microstructure of a given rock type. In this study, we investigate how crack initiation and propagation occurs during uniaxial cyclic loading. The mechanical test was performed on drill cores from an isotropic granite. This granite has a well-developed existing microcrack pattern. A sample that was intact after 35,000 loading cycles of a maximum loading of 122 MPa was used for the microcrack analyses. In order to characterise the microcracks, the tested material was vacuum impregnated with epoxy resin containing fluorescent dye. Using fluorescent and polarised microscopy together with digital image analysis, the length and orientation of different crack types were measured. The results demonstrate that cyclic loading caused new cracks to form and caused extension of existing microcracks. The orientation of the major mode of the existing microcracks correlates with the orientation of a well-developed horizontal joint set. The new cracks occur mainly within feldspar and are oriented parallel to the drill-core axis. However, if the feldspars are altered, cracks are less abundant, because of the disturbance of the crystal lattice. Micas and opaque minerals can improve crack propagation because of the difference in mechanical strength and E-modulus compared to the main rock-forming minerals. (C) 2003 Elsevier B.V. All rights reserved.
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