| 1. |
- Brantberger, M., et al.
(författare)
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Controlling grout spreading in tunnel grouting - Analyses and developments of the GIN-method
- 2000
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Ingår i: Tunnelling and Underground Space Technology. - 0886-7798 .- 1878-4364. ; 15:4, s. 343-352
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Tidskriftsartikel (refereegranskat)abstract
- In order to choose the best grouting technique, predictions of the grouting result can be made. Due to uncertainties in the predictions, control of the grouting during ongoing work is an important step towards a successful result. One method to control the grouting is the GIN-method developed and presented by Lombardi and Deere (1993). The method focuses on controlling the grout spreading in order to minimise the risk of hydraulic uplift and achieve a more uniform spreading around a bore hole. However, this method is described with emphasis on dam grouting. In this paper, theories are analysed and developed from a tunnel grouting point of view. A concept of a normalised pressure and normalised grout spreading is presented that at the same time enables control of the grout spreading distance as well as the risk of hydraulic uplift. Calculations based on field data are also done in order to visualise and discuss the potential use of developed theories. Some conclusions from the performed analyses are that other mathematical relations than those stipulated by the GIN-method better account for the risk of hydraulic uplift and that higher pressures than the rule of thumb stipulates could be used in good rock. So far, the concept of normalised pressure and normalised grout spreading is in its first stage and is studied mainly from a theoretical point of view. Further studies are thus needed.
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| 2. |
- Eriksson, M., et al.
(författare)
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Numerical calculations for prediction of grout spread with account for filtration and varying aperture
- 2000
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Ingår i: Tunnelling and Underground Space Technology. - 0886-7798 .- 1878-4364. ; 15:4, s. 353-364
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Tidskriftsartikel (refereegranskat)abstract
- Grouting as a mean to reduce the ingress of water to underground facilities has been used for decades. With an increased demand for tightness and cost efficiency, the incentive to improve the method has also increased, and the need to understand the governing factors has been focused. The knowledge concerning grouting involves several fields of research, for instance pow in fractured rock and the behaviour of the grouting material. An understanding of these fields is essential in grouting research. Numerical modelling of grout propagation in fracture geometries is one means of achieving such understanding The paper presents how numerical calculations of grout spread and sealing effect can be used for predictions of the grouting result. The calculation concerns pow of grout in a network of conductive elements, representing a fracture geometry with the scope to understand the governing parameters when grouting. The spread of grout is significantly affected by the spatial variability of the fracture aperture. Measurements on grout properties and laboratory experiments show that the grout possesses a limited penetration ability and that filtration of the grout occurs if the aperture of a constriction is smaller than a critical value, i.e. when a filter cake forms in front of constrictions in the pow and the great that passes is filtered. In the paper, a model for filtration of grout is presented. When filtration and limited penetration ability are incorporated in the calculations, additional strong effects are observed. This underlines the need of both a representative geometry, including the fracture variability and measurements of grout properties.
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| 3. |
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| 4. |
- Madsen, Thomas, et al.
(författare)
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Population size and genetic diversity in sand lizards (Lacerta agilis) and adders (Vipera berus)
- 2000
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Ingår i: Biological Conservation. - 1873-2917. ; 94:2, s. 257-262
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Tidskriftsartikel (refereegranskat)abstract
- Because low genetic diversity may threaten the viability of isolated populations, conservation biologists have devoted much effort to quantify genetic variation. Two techniques routinely used involve levels of mini- and microsatellite polymorphism, with the assumption that levels of variation at these parts of the genome will be reflected in levels of variation at other loci. Our data challenge this assumption. We studied six populations of sand lizards (Lacerta agilis) and five populations of adders (Vipera berus), differing considerably in size and degree of isolation. They, therefore, offer an opportunity to examine how population parameters affect genetic variation at different parts of the genome. Relative population size (based on degree of isolation and number of animals) was not correlated with either minisatellite variability or microsatellite heterozygosity. However, our measures of genetic diversity at the Mhc class I loci of both sand lizards and adders revealed a significant correlation between relative population size and Mhc polymorphism: non-isolated/larger populations exhibited higher genetic diversity than did isolated/small populations. Consequently, only the Mhc-based estimates of genetic diversity yielded results in agreement with population genetic theory. (C) 2000 Elsevier Science Ltd. All rights reserved.
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| 5. |
- Stille, Håkan, et al.
(författare)
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Classification as a tool in rock engineering
- 2003
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier BV. - 0886-7798 .- 1878-4364. ; 18:4, s. 331-345
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Tidskriftsartikel (refereegranskat)abstract
- The role of classification in rock engineering and design is discussed. It is important to distinguish between characterization, classification and empirical design method. The classification systems used today should, strictly speaking, either be described as rock mass characterization systems or empirical design methods, as long as the outcome is not organized into classes. The main requirements for a true classification system capable of solving rock-engineering problems are as follows. (1) The reliability of the classes to assess the given rock engineering problem must be estimated. (2) The classes must be exhaustive (every object belongs to a class) and mutually exclusive, (no object belongs to more than one class). (3) The principles of division (rules) governing assignment into the classes must be based on suitable indicators (ground parameters, etc.) and must include the possibility of being updated during construction using the experience gained. (4) These rules must also be so flexible that additional indicators can be incorporated. (5) The uncertainties, or the quality, of the indicators must be established so that the probability of mis-classification can be estimated. (6) The useful system should be practical and robust, and give an economic and safe design. In the author's opinion, none of the main classification systems in use today fulfills these requirements. They may, however, serve as supervised systems as a basis in the development of local systems adapted to the actual site conditions.
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| 6. |
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