| 1. |
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| 2. |
- Akner, Gunnar, 1953-, et al.
(författare)
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Inrätta ett geriatriskt centrum som utvecklar vården
- 2012
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Ingår i: Dagens medicin. - Stockholm : Dagens Medicin Sverige AB. - 1104-7488. ; :8, s. 18-19
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Ett geriatriskt centrum skulle fungera som en utvecklingsmotor för att sprida kunskaper och erfarenheter till hela vård-/omsorgssystemet, skriver tre debattörer
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| 3. |
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| 4. |
- Akner, Gunnar, 1953-, et al.
(författare)
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Personalized Geriatric Medicine
- 2014
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Ingår i: European Geriatric Medicine. - : Elsevier BV. - 1878-7649 .- 1878-7657. ; 5, s. 145-146
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Akner, Gunnar, et al.
(författare)
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Styrningen har blivit ett hot
- 2016
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Ingår i: Svenska Dagbladet. - 1101-2412. ; 25 jul
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 6. |
- Andersen, J. R., et al.
(författare)
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Small-x phenomenology - Summary of the 3rd Lund small-x workshop in 2004
- 2006
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 48:1, s. 53-105
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Forskningsöversikt (refereegranskat)abstract
- A third workshop on small-x physics, within the Small-x Collaboration, was held in Hamburg in May 2004 with the aim of overviewing recent theoretical progress in this area and summarizing the experimental status.
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| 7. |
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| 8. |
- Andersson, Bo, et al.
(författare)
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ON HIGH-ENERGY LEPTOPRODUCTION
- 1981
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Ingår i: Zeitschrift für Physik C Particles and Fields. - 0170-9739. ; C9, s. 233-233
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Tidskriftsartikel (refereegranskat)
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| 9. |
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| 10. |
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| 11. |
- Axelsson, Magnus, 1974, et al.
(författare)
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A robust method to determine the shear strength of cement-based injection grouts in the field
- 2006
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Ingår i: Tunnelling and Underground Space Technology. ; 21:5, s. 499-503
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Tidskriftsartikel (refereegranskat)abstract
- There is no standardised method to directly determine the shear strength of grouts in the field. Determining the shear strength would make it possible to calculate the penetration length of cement-based grouts and hence establish a design of the grouting procedure. By developing a new robust method that consists of a stick sinking in the grout, a direct measurement of the shear strength can be made, using the same set up as the separation test. The sink of the stick depends on the shear force interaction between the grout and the stick, and hence the shear strength of the grout can be determined. To verify the results, the shear strengths obtained with the stick are compared with measurements of the shear strength made with a rotational rheometer in the laboratory. The comparison shows good agreement; hence the stick can be used in the field to determine the yield strength of cement-based grouts.
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| 12. |
- Axelsson, Magnus, 1974, et al.
(författare)
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Design criteria for permeation grouting in hard rock at great depths
- 2008
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Ingår i: Proceedings World Tunnel Congress 2008, Underground facilities for better environmnet and saftey. ; 1, s. 510-520
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Tidskriftsartikel (refereegranskat)abstract
- Grouting at tunnelling in hard rock at great depths below the groundwater table, when constructing a nuclear waste repository for example, makes special demands on the strength of the grout in order to resist groundwater forces. The aim of this study is to distinguish the most important parameters to ensure that suitable grouting can be performed at large depths. Initially, laboratory studies were conducted in order to determine the most critical parameters. The results from the laboratory tests were used in a field study at the Äspö Hard Rock Laboratory in Sweden. The results indicate that the most important characteristics for the rock are the fracture aperture and the groundwater gradient and for the grout: a resolute grouting pressure and sufficient early strength. This implies that for cementitious grouts the yield stress is important and for non-cementitious grouts it is the shear strength prior to gelling. The results emphasise the need to perform hydraulic characterisation of the rock mass in advance. The results also show the importance of performing a proper grouting, especially at large depths where a decreased penetration length of the grout increases the risk of a high gradient and hence erosion of the grout.
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| 13. |
- Axelsson, Magnus, 1974, et al.
(författare)
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Grouting with high water/solid-ratios. Literature and laboratory study
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The grouting methodology in Sweden is developing towards a more extensive use of low water/cement-ratios. The main reason for this development is the better stability of the lower w/c-ratio grouts meaning that the water separation is less than for higher w/c-ratios. However, grouting in low permeable rock or in clay-filled fractures often is performed with high w/c-grouts with better sealing efficiency. Another method that involves high w/c-ratio grouting is “grout thickening” where the grouting starts with a high w/c-ratio and successively lower w/c-ratio is used. In this study the penetration and the stop mechanisms of suspension grouts have been investigated. The study started with a literature survey, from which hypothesis are formed and tested in the laboratory. The laboratory method used was sand column tests. The column, height 1 m and diameter 0.1 m, was filled with 0.9 m sand which was characterised by hydraulic measurements. The grouting was performed with Myanit, a suspension consisting of crushed dolomite with similar rheological characteristics as cement. The main advantage of using Mynait is that it is an inert material. This implies that it will keep it characteristics throughout the grouting and it will not harden with time. In order to obtain different relationships between grout grain size and theoretical aperture and hence groutability, different ratios between water and the solids were used as well as different sand grain distribution.Generally, the conclusions are that the penetration increased with higher water/solid-ratios and the penetration stops due to three different mechanisms. In apertures that are too small for the grout to enter, the sealing occurs due to blocking of the entrance. At the limit on what is possible to penetrate, a higher w/s-ratio leads to a further penetration compared to a grout with lower w/s-ratio. The suspension is not moving as a united front, rather it is a more dilute grout in the front, which leads to sealing by single suspensions grains that blocks the pathway. In larger aperture, the grout penetrates more united and the penetration stops due to equilibrium between driving forces and friction forces.The results implies that the use of “grout thickening” in the field will lead to that the initial higher w/c-ratio grout will penetrate a larger area of the fracture plane and suspension grains will successively plug the constrictions. The thicker grout will then penetrate the larger openings and the combined effect will give decreased permeability compared to only use one w/c-ratio.
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| 14. |
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| 15. |
- Axelsson, Magnus, 1974, et al.
(författare)
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Stop mechanism for cementitious grouts at different water-to-cement ratios
- 2009
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier BV. - 0886-7798. ; 24:4, s. 390-397
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Tidskriftsartikel (refereegranskat)abstract
- Cementitious grouts are the most commonly used grouting material in the world. The general concept of grouting is to propagate the grout in a sufficiently large volume in the grouted medium and hence to have a controlled penetration. This study has been performed in order to determine and test the different mechanisms that result in stoppage of the penetration of cementitious grouts. This is performed as sand column tests in a laboratory study, coupled with grouting in the field. The result shows that three different stop mechanisms can be identified depending on the ratio between the grain size of the grout and the available opening. At an opening up to three times the size of the largest grout grains, penetration does not occur due to clogging of the grains. For an opening larger than five times the largest grain the penetration is unrestricted and stoppage occurs due to equilibrium between the driving and resistance forces. Between these ratios, a transition area exists where the water content determines the penetrability and the stoppage is governed by a filtration process for the grout grains. This implies that grouting with higher water-to-cement ratios results in a larger penetration area and hence by applying the mixture-thickening method during grouting an increased sealing efficiency can be obtained. (c) 2008 Elsevier Ltd. All rights reserved.
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| 16. |
- Axelsson, Magnus, 1974, et al.
(författare)
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The PenetraCone, a new robust field measurement device for determining the penetrability of cementitious grouts
- 2010
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier BV. - 0886-7798. ; 25:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- One of the most crucial parameters for successful grouting is to ensure that the grout can penetrate the necessary apertures. For the most commonly used grout, cementitious grout, the available methods for determining the ability to penetrate apertures involves several measurements with different meshes or similar, which need to be evaluated. However, during the grouting process in the field there is rarely any time for evaluation and the most commonly used field method today stipulates a mesh width through which a certain volume need to pass. This implies that only an indirect measurement of the penetrability is performed. In order to perform direct and fast field measurements of the penetrability, a new, robust measuring device has been developed at Chalmers University of Technology in Gothenburg, Sweden. The device is named PenetraCone and the measuring part consists of a gap that is formed between two conical cylinders. The penetrability characteristics are measured by decreasing this gap as grout flows through. The gap is measured using a dial indicator gauge. Initial tests with the PenetraCone show that two characteristic gaps or widths can be evaluated. The width as the grout flow goes from continuous flow to dripping is termed bfilter and when the flow stops completely it is termed bstop. The parameter bfilter is related to the commencement of clogging or filtration of the cementitious grout. This means that for apertures larger than bfilter the cement passes unrestricted but for narrower apertures filtration will commence. This filtration process will occur in apertures down to bstop, which indicates the smallest aperture that the cement can pass through and for apertures below bstop the cement will not penetrate at all. The device is easy to use and the tests show that consistent values are obtained. The accuracy seems good enough for use as a control of the penetrability of cementitious grouts in the field. For use in production, the PenetraCone should be placed on the grouting rig, after the mixer, so that direct measurements can be performed on the grout that will actually be used for grouting. By relating the measured parameters to the penetrability requirements, quick decisions regarding the quality of the grout can be made directly on the grouting rig.
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| 17. |
- Babaahmadi, Arezou, 1985, et al.
(författare)
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Ageing of cementitious materials for storage of nuclear waste
- 2011
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Ingår i: Nordic Concrete Research. ; Publication No. 43, s. 429-432
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Konferensbidrag (refereegranskat)abstract
- This paper presents an on-going research project dealing with ageing process of cementitious materials in a perspective of hundreds and thousands years. As it is risky to use empirical models for extrapolation of performance data from relatively short term experiments, a mechanism-based (chemo-mechanical coupled) model for safer prediction of longevity of concrete in storage facilities for nuclear waste is needed. The project work involves thermodynamic modeling, development of accelerated aging tests, physical, chemical and mineralogical characterization of young and aged cementitious materials, including mechanical, transport (diffusivity) properties, binding (adsorption) capacities and surface complexation (charging) behavior.
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| 18. |
- Butron, Christian, 1978, et al.
(författare)
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A Swedish grouting design concept: Grouting with silica sol in the Nygård and Törnskog tunnels
- 2012
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Ingår i: Geotechnical Special Publication. - Reston, VA : American Society of Civil Engineers. - 0895-0563. - 9780784412350 ; :228 GSP, s. 826-835
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Konferensbidrag (refereegranskat)abstract
- The scope of this paper is to present two tunnel grouting design case studies where the waterproofing aimed not only to reduce the water inflow to a specified level, but to minimize the number of dripping spots by means of pre-excavation grouting. Every grouted section of around one hundred meters in both tunnels used relevant parameters from the rock and the grout material properties to develop an adequate, pre-excavation grouting design. Both tunnels, constructed in crystalline rock, used silica sol as the main grouting material and were evaluated later by means of control boreholes and dripping characterization. Control boreholes showed a decrease in the transmissivity in these sections, and the dripping characterization showed a reduction in the number of dripping spots compared to the rest of the tunnel, where this pre-excavation grouting concept was not used. This led to minimization of the number of drains used, which was clearly visible in the Nygård case, suggesting that the designs were successful and confirming that an understanding of the rock and grout properties is crucial to the design concept.
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| 19. |
- Butron, Christian, 1978, et al.
(författare)
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Assessment of the transmissivity field in fractured rock: A case study in the tass tunnel
- 2009
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Ingår i: Nordic Symposium of Rock Grouting.
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Konferensbidrag (refereegranskat)abstract
- Water Pressure Tests (WPTs) among other hydraulic tests were conducted in each borehole before and after the pre-excavation grouting of a test tunnel in the Äspö HRL (Hard Rock Laboratory) built in 2008 and 2009 “the TASS tunnel”. This paper shows how data from WPTs can give information on the connectivity and asses the transmissivity fields of fractured rock. The results showed that the connectivity range of the rock before grouting is approximately 3 m, which seems to be a common range in crystalline fractured rocks. Results clearly indicate that the most conductive parts of each fan were where the grout has penetrated the most during grouting. They also show that the reduction of the transmissivity in the rock by means of grouting is about four orders of magnitude within the studied rock volume of a fan. This sealing takes place easily on planar fractures where the transmissivity is high (a few conductive fractures that give the major contribution to the borehole transmissivity) and what is left unsealed is a highly channelized system. This channelized system will be extremely difficult to hit by future boreholes, which will make post-grouting a very complex task.
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| 20. |
- Butron, Christian, 1978, et al.
(författare)
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Drip sealing of tunnels in hard rock: A new concept for the design and evaluation of permeation grouting
- 2010
-
Ingår i: Tunnelling and Underground Space Technology. - : Elsevier BV. - 0886-7798. ; 25:2, s. 114-121
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new pre-excavation grouting concept to prevent dripping and reduce the inflow into a railway tunnel. For this purpose, the tunnel's roof was drip-sealed using colloidal silica and the walls and invert of the tunnel were grouted with cement. The grouting design process followed a structured approach with pre-investigations of core-drilled boreholes providing parameters for the layout. Water pressure tests and pressure volume time recordings were used for the evaluation. Results showed that the design was successful: the total transmissivity was reduced from 4.9 x 10(-08) m(2)/s to the measurement limit (1.6 x 10(-08) m(2)/s), and the dripping was reduced to eight spots from the roof. Improved rock characterisation showed that the grout hole separation was within the transmissivity correlation length and that grouting efficiency depends to a large extent on the dimensionality of the flow system of the rock mass. (c) 2009 Elsevier Ltd. All rights reserved.
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| 21. |
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| 22. |
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| 23. |
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| 24. |
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| 25. |
- Butron, Christian, 1978, et al.
(författare)
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Silica sol for rock grouting: Laboratory testing of strength, fracture behaviour and hydraulic conductivity
- 2009
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier BV. - 0886-7798. ; 24:6, s. 603-607
-
Tidskriftsartikel (refereegranskat)abstract
- A recently introduced non-cementitious grout silica sol is a refined product of colloidal silica, where the particle sizes have been reduced to between 5 and 100 nm. Laboratory tests were performed to determine the behaviour of silica sol as a permeation grout in hard rock. The tests have involved methods Such as fall-cone, unconfined compression, triaxial, and oedometer tests. Samples were tested at different time intervals and in different storage environments. Results showed that the initial strength of silica sol, a few kPa, increases over time. Silica sol has a ductile behaviour during the first few days and then becomes elastic-plastic. Its hydraulic conductivity ranges from 10(-10) to 10(-11) m/s. When immersed in water, silica sol hardens and a thin layer of weaker strength is formed at the surface. However, this layer only extends a couple of millimetres into the sample; beyond that the silica sol is not affected, rendering breakdown by erosion a negligible risk. The conclusions are: (1) the strength obtained in silica sol after hardening is sufficient to withstand most grouting conditions; (2) when sufficiently confined, silica sol is able to withstand loading and unloading cycles: (3) a pH environment of around 11 does not appreciably change the strength of the silica sol; (4) silica sol is a material with low risk of failure under blasting vibrations: and (5) due to its low hydraulic conductivity, silica sol can be compared to low permeable clays.
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| 26. |
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| 27. |
- Claesson Lingehall, Helena, 1965-
(författare)
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Delirium in older people after cardiac surgery : risk factors, dementia, patients’ experiences and assessments
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background:Delirium is common in older people undergoing cardiac surgery. Delirium is an acute or subacute neuro-psychiatric syndrome, characterized by a change in cognition, disturbances in consciousness; it fluctuates, develops over a short period of time and always has an underlying cause. It is associated with a disturbance in psychomotor activity, and is classified according to different clinical profiles such as hypoactive, hyperactive and mixed delirium. Delirium after cardiac surgery is not harmless, it increases the risk of complications such as prolonged stay in hospital, falls, reduced quality of life, reduced cognitive function and increased mortality.Aim:The overall aim of this thesis was to investigate postoperative delirium in older people undergoing cardiac surgery with Cardiopulmonary Bypass (CPB), focusing on risk factors, dementia and patients’ experiences; and to evaluate an assessment for screening delirium.Methods:This thesis compromises four studies. All participants (n=142) were scheduled for cardiac surgery with use of CPB at the Cardiothoracic Surgery Department, Heart Centre, Umeå University Hospital, Sweden, between February and October 2009. Six structured interviews were conducted preoperatively, day one and day four postoperatively, and in home visits, one, three and five years after surgery (2010, 2012 and 2014). The assessment scales used in Studies I, II and IV were: the Mini-Mental State Examination (MMSE) for cognition, the Organic Brain Syndrome Scale (OBS) for delirium, Geriatric Depression Scale 15 (GDS-15) for depression, Katz staircase with Activities of Daily Living (ADL) for participants’ functional status and the Numerical Rating Scale (NRS) for pain. During the hospital stay, nursing staff used the Swedish version of the Nursing Delirium Screening Scale (Nu-DESC) to assess delirium. Semi-structured interviews were also carried out (III) in the one-year follow up. Delirium, dementia and depression were diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders (DSM IV TR).Results: Out of 142 participants 54.9% (78/142) developed delirium after cardiac surgery (I). Independent risk factors, predisposing and precipitating, associated with delirium were: age, diabetes, gastritis/peptic ulcer, volume load during operation, longer time on ventilator in intensive care, increased temperature and plasma sodium concentration in the intensive care unit. Out of 114 participants thirty (26.3%) developed dementia within the five years of follow-up. It was shown that a lower preoperative MMSE score and postoperative delirium were factors independently associated with development of dementia (II). One year after cardiac surgery, participants diagnosed with postoperative delirium described in detail feelings of extreme vulnerability and frailty. Despite this, the participants were grateful for the care they had received (III). Hypoactive was the most common symptom profile for delirium. The Swedish version of Nu-DESC showed high sensitivity in detecting hyperactive delirium, but low sensitivity in detecting hypoactive delirium (IV).Conclusion:Delirium was common among older patients undergoing cardiac surgery. Both predisposing and precipitating factors contributed to postoperative delirium. Preventive strategies should be considered in future randomized studies. It might also be suggested that cognitive function should be screened for preoperatively and patients who develop delirium should be followed up to enable early detection of symptoms of dementia. Whether prevention of postoperative delirium can reduce the risk of future dementia remains to be studied. To minimise unnecessary suffering, patients and next of kin should be informed about and prepared for the risk of delirium developing during hospitalization. The Swedish version of Nu-DESC should be combined with cognitive testing to improve detection of hypoactive delirium, but further research is needed. Healthcare professionals need knowledge concerning postoperative delirium in order to prevent, detect and treat delirium so as to avoid and relieve the suffering it might cause.
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| 28. |
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| 29. |
- Claesson Lingehall, Helena, et al.
(författare)
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Validation of the Swedish version of the Nursing Delirium Screening Scale used in patients 70 years and older undergoing cardiac surgery
- 2013
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Ingår i: Journal of Clinical Nursing. - : Blackwell Publishing. - 0962-1067 .- 1365-2702. ; 22:19-20, s. 2858-2866
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Tidskriftsartikel (refereegranskat)abstract
- AIMS AND OBJECTIVES: Validation of the Swedish version of the Nursing Delirium Screening Scale as a screening tool for nurses to use to detect postoperative delirium in patients 70 years and older undergoing cardiac surgery.BACKGROUND: Delirium is common among old patients after cardiac surgery. Underdiagnosis and poor documentation of postoperative delirium is problematic, and nurses often misread the signs.DESIGN: A prospective observational study.METHODS: Patients (n = 142) scheduled for cardiac surgery were assessed three times daily by the nursing staff using the Nursing Delirium Screening Scale. Nursing Delirium Screening Scale was compared with the Mini Mental State Examination and the Organic Brains Syndrome Scale, evaluated day one and day four postoperatively. Delirium was diagnosed according to Diagnostic and Statistical Manual of Mental Disorders - DSM-IV-TR criteria.RESULTS: A larger proportion of patients were diagnosed with delirium according to the Mini Mental State Examination and Organic Brains Syndrome Scale compared with the Nursing Delirium Screening Scale, both on day one and day four. The Nursing Delirium Screening Scale protocol identified the majority of hyperactive and mixed delirium patients, whereas several with hypoactive delirium were unrecognised.CONCLUSIONS: The Swedish version of the Nursing Delirium Screening Scale was easily incorporated into clinical care and showed high sensitivity in detecting hyperactive symptoms of delirium. However, in the routine use by nurses, the Nursing Delirium Screening Scale had low sensitivity in detecting hypoactive delirium, the most prevalent form of delirium after cardiac surgery. Nursing Delirium Screening Scale probably has to be combined with cognitive testing to detect hypoactive delirium.RELEVANCE TO CLINICAL PRACTICE: Nurses play a key role in detecting delirium. The Nursing Delirium Screening Scale was easy incorporated instrument for clinical practice and identified the majority of hyperactive and mixed delirium, but several of the patients with hypoactive delirium were unrecognised. Training of assessment and cognitive testing seems to be necessary to detect hypoactive delirium.
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| 30. |
- Eklund, Daniel, 1975-
(författare)
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Penetrability due to filtration tendency of cement based grouts
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Grouting as a method of strengthening and sealing rock, soil and concrete is widely used. The possibilities of sealing structures are of great importance from both an economical and environmental point of view. The cost of grouting has in certain projects been as high as the cost for the blasting and excavation of the tunnel. To improve the technique of grouting with cement based material, it is necessary to focus on the properties of the used grout mixture. The ability of a grout to penetrate cavities, channels and porous material, the penetrability, depends on two things, the theology and the filtration tendency. Extensive laboratory tests on stable, low w/c-ratio, injection grouts show that the most significant limitation to their penetrability is the tendency of cement grains to agglomerate into an impermeable filter cake. The properties of a grout that may prevent passing obstructions in the flow path without the cement grains clogging and preventing further penetration is in this work called filtration tendency. An inert material mixture and a cement-based mixture are used for the investigations in this work. The inert material, which is crushed dolomite stone, does not react with the added water in the mixture. The used cement grouts are based upon three types of commercial available Portland cements and four Portland cements with modified grain size distribution curves. Performed tests show that the grain size and grain size distribution is of great importance for the filtration tendency. According to performed experiments with inert and cement material, it seems to be advantageous for the penetrability to have a grain size distribution that contains neither too many fine or coarse grains. It is reasonable to believe that the grain size distribution should be relatively steep (narrow grain size range) between minimum and maximum grain size. The maximum grain size is of importance in terms of for example d95. Too large maximum grain size will prevent penetration of the mixture through obstructions in the flow path. According to performed tests, the value of d95, should be between 4-10 times smaller than the aperture to be penetrated by the cement based mixture. The small grain sizes are also of importance in order to achieve a low filtration tendency of the grout. This is because of the increased tendency for the small grains to flocculation into larger agglomerates, compared to larger grain sizes. The filtration experiments with cement based grouts show that influences of parameters like surface chemistry (use of superplastisisers) and cement chemistry (hydration of cement grains) will strongly affect the filtration tendency of the mixture. To visualize the phenomenon of filtration tendency it can be investigated on a larger scale than usually takes place. Filtration experiments in the scale of approximately 100:1 have been performed in order to see influences of grain concentration, grain shape and the penetrated slot aperture. It can be seen that used grain sizes (monodisperse and inert mixture) should be approximately at least 2-3 times smaller than the aperture to be penetrated by the mixture. Numerical experiments of filtration tendency have also been performed to investigate the possibilities to numerically simulate the influence of grain concentration and slot aperture. The numerical experiments are based on Eulerian flow modelling.
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| 31. |
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| 32. |
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| 33. |
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| 34. |
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| 35. |
- Fransson, Åsa, 1971, et al.
(författare)
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A new parameter to assess hydromechanical effects in single-hole hydraulic testing and grouting
- 2007
-
Ingår i: International Journal of Rock Mechanics and Minings Sciences. - : Elsevier BV. - 1365-1609. ; 44:7, s. 1011-1021
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Tidskriftsartikel (refereegranskat)abstract
- Grouting or filling of the open voids in fractured rock is done by introducing a fluid (grout) through boreholes under pressure. The grout may be either a Newtonian fluid or a Bingham fluid. The penetration of the grout and the resulting pressure profile may give rise to hydromechanical effects, which depend on factors such as the fracture aperture, the pressure at the borehole, and the rheological properties of the grout. In this paper, we postulate that a new parameter, Å, which is the areal integral of the fluid pressure change over the fracture plane, is an appropriate measure to describe the change in fracture aperture volume due to a change in effective stress. In many cases, analytic expressions are available to calculate pressure profiles and the Å parameter. The approach is verified using a fully coupled hydromechanical simulator for the case of a Newtonian fluid. Results of the verification exercise show that the new approach is reasonable and that the Å parameter is a good measure for the fracture volume change: i.e., the larger the Å parameter, the larger the fracture volume change, in an almost linear fashion. To demonstrate the application of the approach, short duration hydraulic tests and constant pressure grouting are studied. It is concluded that using analytic expressions for penetration lengths and pressure profiles to calculate the Å parameter provides a possibility to describe a complex situation and compare, discuss and weigh the impact of hydromechanical couplings for different alternative grouting strategies. Further, the analyses identify an effect of high-pressure grouting, that of uncontrolled grouting of larger fractures and insufficient (or less-than-expected) sealing of finer fractures under certain grouting conditions. © 2007 Elsevier Ltd. All rights reserved.
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| 36. |
- Fransson, Åsa, 1971, et al.
(författare)
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A swedish grouting design concept: Hydraulic testing and selection of grout
- 2012
-
Ingår i: Geotechnical Special Publication. - Reston, VA : American Society of Civil Engineers. - 0895-0563. - 9780784412350 ; :228 GSP, s. 1691-1700
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Konferensbidrag (refereegranskat)abstract
- Some grouting boreholes take no grout and some boreholes take too much, two extremes related to grouting technique, grout properties and the properties of fractures intersecting the boreholes. Successful sealing of rock and soil demands an adequate description of the system to be grouted as a basis for grouting design and selection of grouting material. The basis for this Swedish concept of grouting design is the individual fractures and the hydraulic apertures, b, of these fractures. The hydraulic aperture is an important parameter to describe the grouting behavior and is used to determine if the grout can enter the fractures, the penetrability. The hydraulic aperture also determines the penetration length in addition to grout parameters e.g. yield stress, τ0, and viscosity, μg as well as grouting pressure and time. Knowing these parameters, a proper grouting technique can be adapted. Important input for both design and performance are simple and practical tests of rock and grout and the intention of this paper is to present a testing procedure and give examples from laboratory and field experiences that the approach actually works. © 2012 American Society of Civil Engineers.
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| 37. |
- Fransson, Åsa, 1971, et al.
(författare)
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Effektiv spricköppning och bruksval baserat på vattenförlustmätningar
- 2011
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Ingår i: Bergmekanikdagen 2011/ 12:e ISRM kongressen. ; , s. 13 s.-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Inträngningsförmågan hos cementbruk i spalter har undersökts grundligt. Emellertid styrs bruksspridning av två processer; inträngning av bruket genom sprickorna och blockering och filtrering av bruket i förträngningar längs flödesvägen. I denna uppsats utvärderas den för dessa processer och ett givet bruk kritiska spricköppningen i en spricka (ett spricksystem) med varierande sprickvidd. Med utgångspunkt från detta ges sedan en enkel metod för att skatta sprickvidd och välja brukstyp och reologiska egenskaper för injektering av ett borrhål i en injekteringsskärm.Inledningsvis analyseras möjliga flödesvägar genom ett system av kanaler med perkolations- teori. Denna visar att sprickviddsfördelningen och förgreningarna av möjliga kanaler bestämmer den effektiva öppningen. Resultaten av denna analys kan redovisas med en enkel numerisk modell där inflytandet av medianvidden och variabiliteten kan varieras. Resultaten verifieras sedan med fältdata från Äspölaboratoriet och Nygårdstunneln, som nyligen byggts norr om Göteborg. Sammantaget visar detta att den hydrauliska sprickvidden också är ett rimligt mått på den effektiva spricköppningen (tröskelvärdet för genomflöde) för injekteringsmedlet.Baserat på dessa resultat har ett diagram konstruerats för att välja mellan cementbruk och fintätningsmedel (t.ex. silica sol). Diagrammet baseras på en bestämning av den hydrauliska sprickvidden på grundval av vattenförlustmätningar eller inflödesmätningar i injekteringsborrhålen under antagandet att en spricka står för det huvudsakliga flödet. Även detta diagram har verifierats med data från Äspölaboratoriet och Nygårdstunneln. Analyserna pekar på att en hydraulisk sprickvidd av 50-100 mym är gränsen för vad som kan tätas med cementinjektering. Detta överensstämmer också med resultaten från undersökning av inträngningsförmågan hos cementbruk. Diagrammet är enkelt att använda i fält och en användning bör kunna minska risken för fel bruksval i s.k. nollhål för cement vid injekteringsprojekt.
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| 38. |
- Fransson, Åsa, 1971, et al.
(författare)
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Efterinjektering - Förutsättningar och möjligheter
- 2007
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Ingår i: Bergmekanikdag : föredrag vid Bergmekanikdag i Stockholm. 2007, Stockholm 12 mars 2007. - 0281-4714.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- SammandragEn litteraturgenomgång med fokus på efterinjektering visar att det är svårt att identifiera en "praxis för efterinjektering". Beskrivningarna är ofta kortfattade och angreppssätten olika. Följande uppsats avser att gå igenom några praktiska och teoretiska förutsättningar för efterinjektering och att redovisa strategier för efterinjektering baserade på detta. Analyser och beräkningar är baserade på data från kärnborrhål från Äspölaboratoriet (KA3376B01), Törnskogstunneln (KB971) och Hallandsås (NV01). Arbetet har genomförts genom att vidareutveckla och använda en analysmetod med tre steg. De olika stegen är:I.Prognos av inläckage och injekteringsbehov baserat på kärnborrhål.II.Förslag / underlag för design av injektering.III.Förslag / underlag för design av efterinjektering.Två delmål har varit att ge en redovisning av närbergets hydrogeologiska egenskaper efter förinjektering samt att ge en analys av spridning och tätningsförmåga hos fintätningsmedel i förinjekterat berg.AbstractA literature survey with focus on post-grouting shows that it is difficult to identify a "praxis of post-grouting". The descriptions are much summarised and the approaches are different. This paper aims at giving some practical and theoretical requirements for post-grouting and to identify suitable strategies based on these considerations. Analyses and calculations are based on data from cored boreholes from the Äspö Hard Rock Laboratory (KA3376B01), the Törnskog tunnel (KB971) and the Hallandsås tunnel (NV01). The project was carried through by further development and application of a method of analysis in three steps:I.Prediction of ingress of water and need for grouting based on cored boreholes.II.Proposal and support for grouting design.III.Proposal and support for post-grouting design.The scope of work comprised a description of the hydro-geological properties of the near-zone of the tunnel after pre-grouting and also to present an analysis of the spread of grouts for fine-sealing of pre-grouted rock.
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| 39. |
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| 40. |
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| 41. |
- Fransson, Åsa, 1971, et al.
(författare)
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Estimation of deformation and stiffness of fractures close to tunnels using data from single-hole hydraulic testing and grouting
- 2010
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Ingår i: International Journal of Rock Mechanics and Minings Sciences. - : Elsevier BV. - 1365-1609. ; 47:6, s. 887-893
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Tidskriftsartikel (refereegranskat)abstract
- Sealing of tunnel sin fractured rocks is commonly performed by pre- or post-excavation grouting. The grouting boreholes are frequently drilled close to the tunnel wall, an area where rock stresses can be low and fractures can more easily open up during grout pressurization. In this paper we suggest that data from hydraulic testing and grouting can be used to identify grout-induced fracture opening, to estimate fracture stiffness of such fractures, and to evaluate its impact on the grout performance. A conceptual model and a method are presented for estimating fracture stiffness. The method is demonstrated using grouting data from four pre-excavation grouting boreholes at a shallow tunnel (50 m) in Nygard, Sweden, and two post-excavation grouting boreholes at a deep tunnel (450 m) in Aspo HRL, Sweden. The estimated stiffness of intersecting fractures for the boreholes at the shallow Nygard tunnel are low (2-5 GPa/m) and in agreement with literature data from field experiments at other fractured rock sites. Higher stifness was obtained for the deeper tunnel boreholes at Aspo which is reasonable considering that generally higher rock stresses are expected at greater depths. Our method of identifying and evaluating the properties and impact of deforming fractures might be most applicable when grouting takes place in boreholes adjacent to the tunnel wall, where local stresses might be low and where deforming (opening) fractures may take most of the grout. (C) 2010 Elsevier Ltd. All rights reserved.
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| 42. |
- Funehag, Johan, 1975, et al.
(författare)
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Grouting with silica sol in the Törnskog Tunnel, Grouting design for silica sol in full production
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report describes a full-scale grouting test in the Törnskog Tunnel. The tunnel is part of the Nordlänken project north of Stockholm, which has two separated tunnel tubes. The test was conducted during production of the tunnel during spring 2005 in chainage from 12012 to 12112. A new concept of grouting was designed and executed based on the grouting material silica sol with the brand name Meyco MP320. Silica sol has been succesfully tested before in field tests in Hallandåsen 2003 and in Äspö HRL 2004. This test is the first test with silica sol in full production of a tunnel in hard rock. The initiative was taken by the National Road Administration, Oden Anläggningsentreprenad and AB BESAB. Design of the grouting procedure were based on a standard tests for characterisation of the rock mass. With use of a pareto-distribution curve, the hydraulic apertures of the fractures could be computed, further the hydraulic apertures was used to estimate the inflows to the tunnel. The demands set on the allowable leakage into the tunnel resulted that hydraulic apertures down to 14 μm needed to be sealed. Cement can penetrate and seal apertures down to 0.05 - 0.1 mm and therefore it was necessary to use a grout material that has a better penetrability, like silica sol. The grout, named Meyco MP320, was chosen and the design parameters were established: grout pressure, gel time, grouting time. The desired penetration was 1.2 m in order to limit unnecessary spread of the grout. The design was different than the traditional grouting methods with demands set on the effective grouting time at a prescribed pressure. All grout fans were carefully monitored using hydraulic tests, before and after grouting as well as control of the actual grouting. Last, the result of the grouting was complemented with a drip characterisation. Two types of grout fans were used. One with the above mentioned grout procedure and one based on the grouting procedure normally used in the Törnskogs Tunnel, but with silica sol instead of cement. The first type fan was used when the rock quality was poor. The other when the rock quality was better. The test with these type fans with silica sol were conducted in one tunnel tube, T201, the other tube was grouted with cement following the standard procedure used in the project. This enabled a comparison of the sealing effect between the cement grouted tunnel tube and silica sol grouted tube.The results of the grouting showed that 8 out of totally 9 grouting fans were successful. The designed fans were used in five cases were the rock mass were presumed to be of poor quality, that is with larger fracture zones present. The objective for this field test was to limit the inflow of water to tunnel corresponding to value of the transmissivity of 3.2ּ10-7 m2/s for the grouted section of 100 m. After grouting the achieved transmissivity was calculated to be 6.2ּ10-7 m2/s. The achieved value of the transmissivity is rather close to the desired; the achieved value considers all fans, including the unsuccessful one. No significant conclusion could be made with the comparison of the sealing effect using cement or silica sol as a grouting agent. The conclusion is that the technique of grouting is very important and more effort needs to be done regarding the grouting time.
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| 43. |
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| 44. |
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| 45. |
- Grujic, Mirjana, et al.
(författare)
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Protective role of mouse mast cell tryptase Mcpt6 in melanoma.
- 2020
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Ingår i: Pigment Cell & Melanoma Research. - : Wiley. - 1755-1471 .- 1755-148X. ; 33:4, s. 579-590
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Tidskriftsartikel (refereegranskat)abstract
- Tryptase-positive mast cells populate melanomas, but it is not known whether tryptase impacts on melanoma progression. Here we addressed this and show that melanoma growth is significantly higher in tryptase-deficient (Mcpt6-/- ) versus wild-type mice. Histochemical analysis showed that mast cells were frequent in the tumor stroma of both wild-type and Mcpt6-/- mice, and also revealed their presence within the tumor parenchyma. Confocal microscopy analysis revealed that tryptase was taken up by the tumor cells. Further, tryptase-positive granules were released from mast cells and were widely distributed within the tumor tissue, suggesting that tryptase could impact on the tumor microenvironment. Indeed, gene expression analysis showed that the absence of Mcpt6 caused decreased expression of numerous genes, including Cxcl9, Tgtp2, and Gbp10, while the expression of 5p-miR3098 was enhanced. The levels of CXCL9 were lower in serum from Mcpt6-/- versus wild-type mice. In further support of a functional impact of tryptase on melanoma, recombinant tryptase (Mcpt6) was taken up by cultured melanoma cells and caused reduced proliferation. Altogether, our results indicate a protective role of mast cell tryptase in melanoma growth.
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| 46. |
- Grujic, Mirjana, et al.
(författare)
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The combined action of mast cell chymase, tryptase and carboxypeptidase A3 protects against melanoma colonization of the lung
- 2017
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Ingår i: Oncotarget. - : IMPACT JOURNALS LLC. - 1949-2553. ; 8:15, s. 25066-25079
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Tidskriftsartikel (refereegranskat)abstract
- Mast cell secretory granules are densely packed with various bioactive mediators including proteases of chymase, tryptase and CPA3 type. Previous studies have indicated that mast cells can affect the outcome of melanoma but the contribution of the mast cell granule proteases to such effects has not been clear. Here we addressed this issue by assessing mice lacking either the chymase Mcpt4, the tryptase Mcpt6 or carboxypeptidase A3 (Cpa3), as well as mice simultaneously lacking all three proteases, in a model of melanoma dissemination from blood to the lung. Although mice with individual deficiency in the respective proteases did not differ significantly from wildtype mice in the extent of melanoma colonization, mice with multiple protease deficiency (Mcpt4/Mcpt6/Cpa3-deficient) exhibited a higher extent of melanoma colonization in lungs as compared to wildtype animals. This was supported by higher expression of melanoma-specific genes in lungs of Mcpt4/Mcpt6/CPA3-deficient vs. wildtype mice. Cytokine profiling showed that the levels of CXCL16, a chemokine with effects on T cell populations and NKT cells, were significantly lower in lungs of Mcpt4/Mcpt6/Cpa3-deficient animals vs. controls, suggesting that multiple mast cell protease deficiency might affect T cell or NKT cell populations. In line with this, we found that the Mcpt4/Mcpt6/Cpa3-deficiency was associated with a reduction in cells expressing CD1d, a MHC class 1-like molecule that is crucial for presenting antigen to invariant NKT (iNKT) cells. Together, these findings indicate a protective role of mast cell-specific proteases in melanoma dissemination, and suggest that this effect involves a CXCL16/CD1d/NKT cell axis.
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| 47. |
- Gustafson, Carl-Johan, et al.
(författare)
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Employing human keratinocytes cultured on macroporous gelatin spheres to treat full thickness-wounds : an in vivo study on athymic rats.
- 2007
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Ingår i: Burns. - : Elsevier BV. - 0305-4179 .- 1879-1409. ; 33:6, s. 726-35
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Tidskriftsartikel (refereegranskat)abstract
- Providing cutaneous wounds with sufficient epidermis to prevent infections and fluid loss is one of the most challenging tasks associated with surgical treatment of burns. Recently, application of cultured keratinocytes in this context has allowed this challenge to be met without several of the limitations connected with the use of split-thickness skin grafts. The continuous development of this novel approach has now revealed that transplantation of cultured autologous keratinocytes as single-cell suspensions exhibits several advantages over the use of cultured epidermal grafts. However, a number of methodological problems remain to be solved, primarily with regards to the complexity of culturing these cells; loss of viability and other negative effects during their preparation and transportation; the relatively long period of time required following transplantation to obtain a sufficiently protective epidermis. In the present investigation we attempted to eliminate these limitations by culturing the keratinocytes on macroporous gelatin spheres. Accordingly, the efficacies of normal human keratinocytes in single-cell suspension or growing on macroporous gelatin spheres, as well as of split-thickness skin grafts in healing wounds on athymic rats were compared. Human keratinocytes were found to adhere and proliferate efficiently both on the surface and within the pores of such spheres. Transplantation of such cells adherent to the spheres resulted in significantly more rapid formation of a stratified epidermis than did transplantation of single-cell suspensions or spheres alone. Twenty-three days after transplantation, the epidermis formed from the cells bound to the spheres was not as thick as the epidermis on wounds covered with split-thickness skin grafts, but significantly thicker than on wounds to which single-cell suspensions, spheres alone or no transplant at all was applied. Furthermore, fluorescence in situ hybridisation revealed that the transplanted keratinocytes, both those adherent to gelatin spheres and those in single-cell suspension, were components of the newly formed epidermis. These findings indicate that application of biodegradable macroporous spheres may prove to be of considerable value in designing cell-based therapies for the treatment of acute and persistent wounds.
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| 48. |
- Gustafson, Gunnar, 1945, et al.
(författare)
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A new stochastic model for fracture transmissivity assessment
- 2008
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Ingår i: Water Resources Research. - 0043-1397 .- 1944-7973. ; 44
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Tidskriftsartikel (refereegranskat)abstract
- A new stochastic model is proposed for fracture counts and transmissivities in a borehole interval. This new model incorporates several empirical observations, including: (i) Clustering of fractures; (ii) Exponential fracture spacings; (iii) Transmissivities extending over several orders of magnitude; (iv) Power law probability tail for transmissivities at finer scales; (v) Log-normal transmissivities at larger scales; and (vi) Dependence between fracture counts and transmissivities. Several example applications are provided using borehole data from Sweden
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| 49. |
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| 50. |
- Gustafson, Gunnar, 1945, et al.
(författare)
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Characterisation of the hydraulic properties of fractured rock from grouting data
- 2008
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Ingår i: Toyama, Japan-IAH 2008 Toyoma: Integrating Groundwater Science and Human Well-Being.
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Konferensbidrag (refereegranskat)abstract
- Pre-grouting of tunnels produces a large amount of data that so far has been of little use to analyse and characterize the properties of the rock. A fan of grouting boreholes is drilled ahead of the tunnel to excavate. In the boreholes water pressure tests (WPT) are made before grouting. After grouting control holes are drilled where new WPTs are performed. These data can give new information on the hydraulic structure of a fractured crystalline rock. The methods and findings are demonstrated for a test segment of a newly constructed railway tunnel, the Nygård tunnel. The paper shows also how the WPT data can be used to assess the characteristic size of the conductive fractures and channels from the WPTs before and after grouting. The interpretation is that there is a system of conductive fractures, which are relatively easy to fill with grout. They are connected by a network of less pervious channels, which make up low permeability connections between the conductive fractures. They are difficult to intersect by a borehole and are thus difficult to grout. Finally the findings support a conceptual model of the rock as a system of sparse conductive two-dimensional fractures connected by much less conductive one-dimensional channels.
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