| 1. |
- Fransson, Åsa, 1971, et al.
(författare)
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Characterization of fractured crystalline rock: two Swedish in situ field experiments
- 2014
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Ingår i: 1st International Discrete Fracture Network Engineering Conference, 20-22 oct 2014, Vancouver, Canada.
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Konferensbidrag (refereegranskat)abstract
- Construction of a nuclear waste repository requires information and an understanding of the fractured rock. The Swedish concept for nuclear waste deposition that is currently being developed by the Swedish Nuclear Fuel and Waste Management Co (SKB) includes a natural barrier in the form of crystalline rock, and engineered barriers in the form of bentonite and a copper canister. This paper aims to present two in situ field experiments: the first is the Large fractures experiment and the second is BRIE, the Bentonite Rock Interaction Experiment. Important issues include possible deformation (shearing) of fractures and deformation zones influencing the localization of canisters, and fluid flow, resulting in hydration of the bentonite. The aim of Large fractures is to further develop strategies and integrated investigation and modelling methodology for the identification and characterization of geological structures to ensure that (size) determination of large fractures or minor deformation zones to a greater extent can be based on real properties and to a lesser degree on a criterion related to the existence of a full perimeter fracture – tunnel intersection. BRIE is a field experiment which addresses the hydraulic interaction between the system components of compacted bentonite and the near-field host rock composed of hard and fractured bedrock. The above experiments are presented in terms of investigations performed to obtain discrete fracture descriptions. Grouting of fractures intersecting the investigation borehole of the Large fractures experiment was designed based on field data and a decrease in flow from above 200 liters/min to below 1 liter/min was achieved. The magnitude of the transmissivity of the fracture/deformation zone that was grouted indicates a large fracture size. This is also indicated by the ongoing integrated interpretation (geology, hydrogeology and geophysics). Results from BRIE show that hydration is uneven and is controlled by the main conductive fracture, highlighting the need for a relevant fracture description.
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| 2. |
- Fransson, Åsa, 1971, et al.
(författare)
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Swedish grouting design: hydraulic testing and grout selection
- 2016
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Ingår i: Ground Improvement. - : Thomas Telford Ltd.. - 1365-781X. ; :4, s. 275-285
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Tidskriftsartikel (refereegranskat)abstract
- © 2016, Thomas Telford Services Ltd. All rights reserved. To ensure successful sealing of rock and soil, an adequate description of the system to be grouted is required as a basis for the grouting design and the selection of the grouting material. In rock, the individual fractures and the hydraulic apertures of these fractures form the basis of the Swedish grouting design concept. The hydraulic aperture is a key parameter when describing grouting behaviour and it is used to determine the extent to which the grout can enter fractures - that is, the penetrability. The hydraulic aperture also determines the penetration length, and therefore the grout parameters (e.g. yield stress and viscosity) as well as the grouting pressure and time needed to be adopted to the hydraulic aperture. Once these parameters are chosen, a suitable grouting technique can be adopted. Simple, practical rock and grout tests are important inputs to ensure correct design and performance. The aim of this paper is to present a testing procedure and provide examples from laboratory and field experience to demonstrate that the approach also works in practice.
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| 3. |
- Funehag, Johan, 1975, et al.
(författare)
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Grundläggande egenskaper för injektering och inträngning av bruk
- 2014
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Ingår i: Bergmekanikdag 2014, Stockholm.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Injektering i hårt berg inkluderar vetenskaper som flöde av vätskor, reologi, hydrogeologi, material kännedom, geologi och annat. Att faktiskt förstå och ha en känsla för hur flöde fungerar i sprickor är viktigt. Detta kan lätt glömmas av och energi läggs allt som oftast på andra delar exempelvis på materialetkunskap. Denna artikel syftar till att beskriva hur flöde sker i sprickor och bör kunna bidra till en känsla av hur flödet av bruk faktiskt sker. Artikeln utgår från framtagna samband för spridning baserat på Binghamflöden för att beskriva hur yttre händelser som kan uppträda vid vanlig injektering kan påverka spridningen. En verifikation av inträngningslängder i en nyligen tillverkad sprickmodell används för att visa hur ett Binghamflöde beter sig. Både spridning och hur ett sambandshål påverkar spridningen visas samt hur detta kan påverka designkriterier. Filmvisning av injekteringsflöde i sprickrepliken kommer säkerligen bringa lite mer klarhet i hur teoretiska beräkningar kan användas som modeller.
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| 4. |
- Funehag, Johan, 1975, et al.
(författare)
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How the Pressure Build-Up Affects the Penetration Length of Grout-New Formulation of Radial Flow of Grout Incorporating Variable Pressure
- 2017
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Ingår i: Geotechnical Special Publication. - Reston, VA : American Society of Civil Engineers. - 0895-0563. - 9780784480793 ; :288, s. 143-151
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Konferensbidrag (refereegranskat)abstract
- For around two decades of research and development in the field of grouting in hard jointed rock, the design process has taken some leaps forward. Stille and Gustafson, 2005 and Funehag and Gustafson 2008, shows how a grouting design can be computed. A grouting design in hard rock can based on the penetration length of grout in rock fractures. The design comprises considerations of the fracture apertures in the rock mass, the type of grout and its rheological properties and how the grout is injected i.e pressure and grouting times. When knowing these parameters an optimized geometry fitting the design is made. Thörn, et al, 2014 describes a fundamental analysis with a comprehensive tool to retrieve the fracture distribution and aperture distribution of the fractures crossing a cored borehole. The data needed about the core is geological mapping and hydraulic section tests. In Gustafson, Claesson and Fransson, (2013) a full derivation of a radial Bingham flow in a slit is described for constant pressure. By optimizing with a specific pressure and an efficient grouting time (efficient time means the time when the pressure has reached the designed pressure) a prognosis a more realistic time consumption for grouting can be computed. However, the time it takes to reach a certain pressure is dependent on the capacity of the pump and the how large the fractures widths are. For poorly chosen pumps together with large fractures the time to reach the design pressure can be significant. The overall objective for this new formulation was to involve the grouting pressure as a variable rather than constant. A pressure build-up mimic more a realistic pumping scenario which enables better prognosis of grouting works. This paper brings up this new formulation of the radial Bingham flow with variable injection pressure in slit. The benefits of this new formulation is that it can easily be integrated in other computer programs. One program that uses this new formulation is a grouting simulator owned and developed by Edvirt AB. The simulator has been used to pedagogically demonstrate how a variable pressure and restrictions in grout flow (the pump capacity) affect the penetration length. Further, the results show that it can be used to predict suitable pump capacity to fit the coming grouting works.
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| 5. |
- Funehag, Johan, 1975, et al.
(författare)
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Radial penetration of cementitious grout - Laboratory verification of grout spread in a fracture model
- 2018
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier BV. - 0886-7798. ; 72, s. 228-232
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Tidskriftsartikel (refereegranskat)abstract
- During the past two decades of research and development in the field of grouting in hard jointed rock, the design process has taken a number of significant leaps forward. A grouting design in hard rock can now be based on the penetration length of grout in individual rock fractures. For cementitious grouts, the most common rheological model used is the one for a Bingham fluid. The model is a conceptualisation of grout spread where two rheological properties of the grout viscosity and yield stress govern the penetration length along with the fracture aperture and applied grouting overpressure. This paper focuses on verification of radial Bingham flow of cementitious grout using a fracture model constructed from acrylic glass. Each test conducted using the fracture model was filmed, allowing the grout spread to be analysed as penetration length over time. The measured penetration lengths were then compared with analytical solutions derived for Bingham grout in a plane parallel fracture. The results indicate that the penetration of cementitious grout in fracture apertures of 125 gm and 200 gm is verified for up to 40% of the maximum possible penetration length. This can be compared to normal grouting, where the penetration lengths achieved are around 20% of the maximum penetration length.
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| 6. |
- Thörn, Johan, 1986, et al.
(författare)
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Fracture Deformation Measurements during Grouting in Hard Rock
- 2012
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Ingår i: Geotechnical Special Publication. - Reston, VA : American Society of Civil Engineers. - 0895-0563. - 9780784412350 ; :228 GSP, s. 836-845
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Konferensbidrag (refereegranskat)abstract
- When a fracture system in crystalline rock is grouted the rock mass may deform. Such deformations may reduce the grouting efficiency since new flow paths are opened. The work presented here show that deformations occur at hydraulic tests and grouting and that deformation can be measured and evaluated as stiffness from in situ tests. Deformation measurements, hydraulic testing, and grouting was conducted in spring 2010 in the Hallandsås tunnel and hydraulic testing in a service tunnel in Gothenburg (Runslätt and Thörn, 2010). For measuring physical deformation recently developed equipment from Chalmers University of Technology was used. Deformations were measured seven times in the same borehole. Three measurements were during grouting, and the remaining four from water pressure tests. Most deformations occurred at pump pressures of 1-1.4 MPa, which is lower than the calculated normal rock stress. Stiffness has been evaluated in several ways, including a new method, (Fransson, et al., 2010). Generally the evaluated stiffness is lower in the Hallandsås tunnel than in the Gothenburg tunnel. The results show agreement with other in situ experiments.
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| 7. |
- Andersson, Patrik, 1974, et al.
(författare)
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Framtidsbilder för samhällsbyggnad
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Framtidsbilder för samhällsbyggnad 2020De kommande 15 åren står institutionen för Bygg- och miljöteknik inför stora förändringar. Därför har institutionen initierat projektet Framtidsbilder 2020 där man engagerat en framtidspanel bestående av elva yngre disputerade forskare. Arbetet inleddes med ett breddgruppsmöte där 110 personer representerande institutionens personal och studenter deltog. Vid mötet identifierades ett antal trender och osäkra utvecklingar som påverkar framtiden inom samhällsbyggnadsområdet. Deltagarna bidrog också med idéer till en önskvärd utveckling, vilket har sammanställts och utgör grunden till en gemensam önskvärd framtid/vision för institutionen. Materialet från breddgruppsmötet har bearbetats av Framtidspanelen och resulterat i fyra scenarier som beskriver hur samhällsbyggnadsområdet kan se ut år 2020. Syftet med framtidsbilderna är att de ska vara vägledande för institutionens beslut och förhållningssätt under de kommande åren.Fyra scenarierTurning TorsoSamhället präglas av en ekonomi som är på uppgång, och av ett nytänkande och öppet samhälle. Materiell status och individualism är viktigt. Detta leder till en hög arbetsbelastning samt krav på exklusiva varor av hög kvali-tet. Det finns en stor medvetenhet om miljöpåverkan och klimatförändringar och lösningarna för att klara energiförsörjningen är innovativa.Eco-metropolenDet sveper en grön våg genom dagens samhälle. Under de senaste 15 åren har vi insett att jorden skall vara en bebolig plats även åt dem som kommer efter oss. Vi söker ständigt efter nya, mer förfinade metoder att tillvarata de resurser vi har. Samhället och individen är i balans. Ekonomin är god och vi är miljömedvetna, trygga och integrerade. Nytänkande premieras och icke- materialistiska värderingar står högt i kurs. Vi tänker individuellt, men agerar mer än gärna för kollektivets bästa. Utbildning är gratis TrädgårdsstadenEtt samhälle där vi lärt oss hantera stress, men känner oss otrygga och helst umgås i slutna sociala sammanhang. Vi bor enkelt inne i stan, eller gärna på landsbygden nära storstäderna. Minskade behov av högutbildade i samhället gör att vi har svårt att rekrytera studenter till teknikutbildningar. Det traditionella tankesättet leder till kulturkrockar med företag och personer från andra länder.Gated communitiesFörsämrad ekonomi och ökad egoism har lett fram till ett stressat, otryggt och segregerat samhälle. Accelererande klimatförändringar och ökad miljö-påverkan skrämmer oss, men trots det åtgärdar vi inte problemen, utan koncentrerar oss på konsekvenserna. Arbetslöshet i samhällsbyggnadssek-torn leder till sänkt status för samhällsbyggaren. Vi har därför svårt att rekrytera studenter, och även forskningen har låg status.
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| 8. |
- 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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| 9. |
- 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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| 10. |
- 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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