| 1. |
- Bhanbhro, Riaz, et al.
(författare)
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Basic description of tailings from Aitik focusing on mechanical behavior
- 2013
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Ingår i: International Journal of Emerging Technology and Advanced Engineering. - 2250-2459. ; 3:12, s. 65-69
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Tidskriftsartikel (refereegranskat)abstract
- Tailings are artificial granular materials that behave different as compared to natural soil of equal grain sizes. Tailings particle sizes, shapes, gradation and mechanical behavior may influence the performance of tailings dams. Hence it is essential to understand the tailings materials in depth. This article describes present studies being carried out on Aitik tailings. Basic tailings characteristics including specific gravity, phase relationships, particle sizes, particle shapes and direct shear behavior are presented in this article. The results showed that particles size decreases along depth from surface for collected sample locations. The angularity of the particles increases as the grain size decreases. Vertical height reduction was observed during shearing of samples by direct shear tests.
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| 2. |
- Bhanbhro, Riaz, et al.
(författare)
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Mechanical Properties of Soft Tailings from a Swedish Tailings Impoundment : Results from Direct Shear Tests
- 2014
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Ingår i: Electronic Journal of Geotechnical Engineering. - 1089-3032. ; 19:Z, s. 9023-9039
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Tidskriftsartikel (refereegranskat)abstract
- The shear strength of tailings can vary depending upon the type of ore and method of construction. Tailings dams may possess loose layers in subsequent layers, which may have low shear strength. Since the tailings dams are made-up to last for longer times, the strength parameters and material behaviors are essential to understand, especially potential for static liquefaction in loose layers. This article presents the results from direct shear tests performed on samples from loose layer of a tailings dam. Both drained and undrained tests are carried out. The results indicated the strain hardening behavior in tailings material which indicates loose condition. The shear strength was found to be relatively low as compared to typical values of tailings in literature. A contractant volume behavior was observed for all the tests. During shear tests the vertical height reductions in samples were observed. These changes were significantly increased after peak shear followed by slight increment in pore pressure along shearing angle. The reasons for these height changes are not fully known, but may be a rearrangement in skeleton or breakage of particles during shear which needs further investigative studies.
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| 3. |
- Berglund, Andreas, et al.
(författare)
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Comparison between temperature based thaw weakening prediction model and field observation methods
- 2011
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Ingår i: Proceedings of the 21st International Conference on Port and Ocean Engineering under Arctic Conditions. - Montreal.
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Konferensbidrag (refereegranskat)abstract
- Structures like roads and port yards located in cold climate are affected by freezing and thawing every year. The global trend of a warmer climate and temperatures around 0°C for longer periods of time will change the freezing/thawing behaviour in many locations. The tendency will changeto have several freezing /thawing cycles in a given location every year. The bearing capacity of low volume roads and simple port yards will be affected by a prolonged thawing period with lower bearing capacity as a consequence. Bearing capacity problems can lead to increased costs for traffic as well as increased maintenance costs. Due to very high costs for destroyed structuresduring thaw, a lot can be gained if bearing capacity problems at a given site can be forecasted well in advance in order not to destroy the structure. Such a method should preferably be based upon simple measurements like air temperatures to make it easy to use also in remote areas. In the described temperature based model air and ground temperatures are used to develop anaccumulated thaw index and corresponding limits. When the thaw index limit is reached, the construction at the evaluated depth thaws, leading to increased pore water pressure and reduction of strength and bearing capacity. This paper presents a study of the application of the model at low volume roads in Sweden. Bearing capacity at the road was evaluated from field tests by falling weight deflectometer (FWD) test carried out 24 times during the thawing season i.e.March 4 through June 9. Predictions made by the model were compared with the subgrade module evaluated from the FWD series. The results show that the model might be possible to use in Sweden and elsewhere if minor adjustments are carried out.
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| 4. |
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| 5. |
- Dahlberg, Anders, et al.
(författare)
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Den nya rödlistan har 746 svampar
- 2010
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Ingår i: Svensk mykologisk tidskrift. - 1653-0357. ; 31:2, s. 37-47
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Tidskriftsartikel (refereegranskat)abstract
- The new Red List that was recently presented by the Swedish Species Information Centre (Gärdenfors 2010) includes 746 species of fungi considered to be threatened. Compared to the previous Red List published in 2005, 36 species have been down-listed whereas 150 species have been added, thus the list has increased by 114. The changes are above all due to increased knowledge of taxonomy, ecology and distribution. In the present paper members of the Species Specialist Group for Fungi 2006-2010 summarize the background and results of the red-listing process and present the habitats in which the red-listed species occur.
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| 6. |
- Dahlberg, Anders, et al.
(författare)
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Svampar – Fungi
- 2010
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Ingår i: Rödlistade arter i Sverige 2010 – The 2010 Red List of Swedish Species. - 9789188506351 ; , s. 231-246
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Edeskär, Tommy, et al.
(författare)
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Grundläggning av vindkraftverk med hänsyn till tjäle
- 2010
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Ingår i: Bygg och Teknik. - 0281-658X .- 2002-8350. ; 102:1, s. 68-73
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- På grund av den snabba utbyggnaden av vindkraftverk är erfarenheten från byggande i kallt klimat för dessa konstruktioner begränsad. Den forskning som bedrivs idag är mestadels inriktad mot vindkraftens miljöpåverkan samt frågor för att underlätta utbyggnaden och förbättra kostnadseffektiviteten, Statens energimyndighet (2008). Utbyggnad av vindkraftverk i extrema miljöer skapar nya frågor som bör utredas för att säkerställa verkens kvalitet i ett långtidsperspektiv. I denna artikel vill vi belysa frågan om tjäle och hur den är kopplad till grundläggning av vindkraftverk.
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| 8. |
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| 9. |
- Rodriguez, Juan M., et al.
(författare)
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Particle Shape Quantities and Measurement Techniques–A Review
- 2013
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Ingår i: Electronic Journal of Geotechnical Engineering. - : Mete Öner. - 1089-3032. ; 18/A, s. 169-198
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Tidskriftsartikel (refereegranskat)abstract
- It has been shown in the early 20th century that particle shape has an influence on geotechnical properties. Even if this is known, there has been only minor progress in explaining the processes behind its performance and has only partly implemented in practical geotechnical analysis. This literature review covers different methods and techniques used to determine the geometrical shape of the particles. Particle shape could be classifying in three categories; sphericity - the overall particle shape and similitude with a sphere, roundness - the description of the particle’s corners and roughness - the surface texture of the particle. Thecategories are scale dependent and the major scale is to sphericity while the minor belongs to roughness. The overview has shown that there is no agreement on the usage of the descriptors and is not clear which descriptor is the best. One problem has been in a large scale classify shape properties. Image analysis seems according to the review to be a promising tool, it has advantages as low time consumption or repeatability. But the resolution in the processed image needs to be considered since it influences descriptors such as e.g. the perimeter. Shape definitions and its potential role in soil mechanics are discussed.
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| 10. |
- Söderström, Patrik, et al.
(författare)
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Snow grooming using machine guidance for piste management processes : Case study: Ormberget ski piste
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The snow is an increasingly precious commodity to the ski industry's production of pistes. To preserve this commodity is the basis for economic production. The wear on the groomed snow consists primarily of two reasons: skiers and melting. A slope that is optimally processed will last longer and require less maintenance. In addition to this obvious that maintenance must be planned based on where wear has taken place there is an additional planning variable, namely time. Timing is of utmost importance when it comes to snow as a material. A process model will be presented covering a systematic approaches how road construction technologies can be adapted to the snow grooming process. The expected results are a process model which can be used in order to optimize the snow grooming management in order to extend the skiing season. There is possibly two ways of doing this. Firstly to optimize the snow mass haul management process during the skiing season. Secondly re-build the different piste off season to create better environmental conditions during season. This study consists of four kinds of data. Laser scanned data for 3D terrain modeling of ski piste (ground) and collected data by snow groomer for 3D terrain modeling of ski piste during the objective period of investigation. The differences between 3D terrain models by laser scanning and snow groomer is representative of snow depth for corresponding day. Furthermore, in order to verify the method, snow depth and snow surface are measured by group of students from Luleå University of Technology.
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