| 1. |
- 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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| 2. |
- Draganović, Almir, et al.
(författare)
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Bleeding and bleeding measurement of cement-based grout
- 2012
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Ingår i: Grouting and deep mixing 2012. - Reston, VA : American Society of Civil Engineers (ASCE). - 9780784412350 ; , s. 1681-1690
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Konferensbidrag (refereegranskat)abstract
- Grouting is a common method of sealing rock in various geotechnical projects, and the bleeding of cement-based grout is an often-discussed issue. Current cylinder measuring methods for the estimation of the bleeding of cement-based grouts originate from the measurement of the bleeding of cement pastes used in ordinary building practices. Whether bleeding measured with these methods is relevant to bleeding in small fractures in rocks is one of the main questions in this study. This study showed that the bleeding process is very complex and is governed by different physical and chemical processes like sedimentation, consolidation, flocculation and hydration. It also showed that consolidation has little influence on bleeding in fractures. Bleeding in fractures is mainly the result of sedimentation. In addition, the study showed that the results measured using cylinder methods are not relevant for the bleeding of grout in fractures and that voids in the fractures caused by bleeding can be refilled during grouting. The bleeding should occur to a considerably lower extent in rock fractures, if it occurs at all.
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| 3. |
- Fransson, Åsa, 1971, et al.
(författare)
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A swedish grouting design concept: Hydraulic testing and selection of grout
- 2012
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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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| 4. |
- Funehag, Johan, 1975, et al.
(författare)
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New frontier in post-grouting of tunnels 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. 846-856
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Konferensbidrag (refereegranskat)abstract
- Post-grouting is a difficult task. It is often coupled with high costs and a result that is difficult to quantify. An infrastructure tunnel in an urban city in southern Sweden was used to develop and implement design methodology for post-grouting. The water inflow measured in weirs prior to post-grouting was about 3.8 l/min/100 m. The task of sealing low water inflows to achieve even lower ones takes a lot of effort and determination. The tunnel was built in the 1970s using the traditional drill-and blast method. During the pre-investigations of the project the analysis showed very good pre-grouting, giving a sealed zone of almost 10 meters. The tunnel had a large, sealed zone with a smaller hydraulic gradient and only narrow fractures were left unsealed. The grout chosen was the newly developed silica sol for the presumed narrow fractures and a robust cement grout if large inflows were hit by the grout holes. The tunnel is small, roughly 12 m2 and heavily congested with cables and heating pipes, making it difficult to use traditional machinery. The tunnel section, 90 m in length, was divided into three different sub-sections, each with specific goals. The result showed that the strategy developed worked well and production was more rapid than presumed. The targeted water inflow rate of 1 l/min was met. © 2012 American Society of Civil Engineers.
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| 5. |
- Hernqvist, Lisa, 1968, et al.
(författare)
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A Swedish Grouting Design Concept: Decision Method for Hard Rock Tunneling
- 2012
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Ingår i: Geotechnical Special Publication. - Reston, VA : American Society of Civil Engineers. - 0895-0563. - 9780784412350 ; :228 GSP, s. 816-825
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Konferensbidrag (refereegranskat)abstract
- Efficient grouting of hard rock requires adequate knowledge of the water-bearing fracture system in the rock mass. The observational method approach involves identifying different possible scenarios and relating them to predefined strategies for grouting design. Parameters useful in preparing a relevant description of the rock mass are presented, as well as a method for choosing a conceptual model. The implications of different fracture systems for the grouting design are discussed. A method is presented for deciding whether grouting is needed in order to ensure a high degree of probability that tunnel leakage will remain below the inflow requirements. The methods presented are applied to data from a real tunnel to illustrate the procedures.
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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. |
- Yaghoobi Rafi, Jalaleddin, et al.
(författare)
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Applying Real Time Grouting Control Method in Sedimentary Rock
- 2012
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Ingår i: Grouting and deep mixing. - Reston, VA : American Society of Civil Engineers (ASCE). - 9780784412350 ; , s. 1450-1459
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Konferensbidrag (refereegranskat)abstract
- We report on preliminary studies of low (14 at.%) and high (53at.%) concentration Mn doped MgO films deposited by co-sputtering from metallic Mn and Mg targets. The structural, surface morphologies and magnetic properties of the films of different thickness were studied. All the as grown films are found to be amorphous and film surfaces are found to be flawless and homogeneous. We observe at room temperature robust ferromagnetic loops with a saturation magnetization value that is a function of film thickness reaching a maximum of ≃38.5 emu/cm3 in the Mn0.53Mg0.47O film at a thickness of ≃92 nm. In thicker films room-temperature ferromagnetic ordering is suppressed and eventually at a thickness around 120nm the expected diamagnetism of the bulk appears. The origin of ferromagnetism may be attributed to cation defects at the Mg-site.
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