| 1. |
- 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. ; 169:4, 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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| 2. |
- 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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| 3. |
- Odqvist, Lina, et al.
(författare)
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Genetic variations in A20 DUB domain provide a genetic link to citrullination and neutrophil extracellular traps in systemic lupus erythematosus
- 2019
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 78:10, s. 1363-1370
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Genetic variations in TNFAIP3 (A20) de-ubiquitinase (DUB) domain increase the risk of systemic lupus erythematosus (SLE) and rheumatoid arthritis. A20 is a negative regulator of NF-κB but the role of its DUB domain and related genetic variants remain unclear. We aimed to study the functional effects of A20 DUB-domain alterations in immune cells and understand its link to SLE pathogenesis. Methods: CRISPR/Cas9 was used to generate human U937 monocytes with A20 DUB-inactivating C103A knock-in (KI) mutation. Whole genome RNA-sequencing was used to identify differentially expressed genes between WT and C103A KI cells. Functional studies were performed in A20 C103A U937 cells and in immune cells from A20 C103A mice and genotyped healthy individuals with A20 DUB polymorphism rs2230926. Neutrophil extracellular trap (NET) formation was addressed ex vivo in neutrophils from A20 C103A mice and SLE-patients with rs2230926. Results: Genetic disruption of A20 DUB domain in human and murine myeloid cells did not give rise to enhanced NF-κB signalling. Instead, cells with C103A mutation or rs2230926 polymorphism presented an upregulated expression of PADI4, an enzyme regulating protein citrullination and NET formation, two key mechanisms in autoimmune pathology. A20 C103A cells exhibited enhanced protein citrullination and extracellular trap formation, which could be suppressed by selective PAD4 inhibition. Moreover, SLE-patients with rs2230926 showed increased NETs and increased frequency of autoantibodies to citrullinated epitopes. Conclusions: We propose that genetic alterations disrupting the A20 DUB domain mediate increased susceptibility to SLE through the upregulation of PADI4 with resultant protein citrullination and extracellular trap formation.
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| 4. |
- Runslätt, Edward, 1984, et al.
(författare)
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Statistical Evaluation of Groutability Using Data from Hydraulic Tests and Fracture Mapping Case Studies from Sweden
- 2017
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Ingår i: Geotechnical Special Publication. - Reston, VA : American Society of Civil Engineers. - 0895-0563. ; 0:288, s. 185-195
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Konferensbidrag (refereegranskat)abstract
- Sweden has a long history of research within the field of rock fissure grouting in hard crystalline rock mass due to strict environmental requirements regarding allowable ground water draw down. These requirements normally implies that fractures down to aperture size between 50 to 100 μm needs to be sealed and within these ranges the size of the particles for cementitious grouting agents becomes a limiting factor. For a grouting design it is therefore of importance to consider the aperture size distribution of the rock mass in order to predict the groutability for both cementitious and non-cementitious grouting agents. Transmissivity data from hydraulic tests (water pressure tests) and number of fractures along a borehole can be assessed from core logging for further use as input for a statistical interpretation of fracture data to simulate an aperture size distribution. A methodology developed at Chalmers University of Technology in Gothenburg, Sweden, is proposed. The method is a statistical evaluation of groutability (SEG) and is based on the Pareto distribution. A computational design tool has been developed to simplify the use of the statistical evaluation and to make the research more accessible to end users, designers, in the grouting industry. The aim of this article is to present two case studies where the statistical interpretation of fracture data is performed by using the computational design tool and how the outcome can be of great use in finding a more accurate grouting design. The case studies include fracture data sets from two large infrastructure rock tunnel projects in Sweden; a road tunnel in Stockholm and a railroad tunnel in Gothenburg.
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| 5. |
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| 6. |
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| 7. |
- Thörn, Johan, 1986, et al.
(författare)
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Calculation tool for hydraulic characterization during grouting design
- 2016
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Ingår i: 8th Nordic Grouting Symposium. - 9788282080507 ; , s. 28-40
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Konferensbidrag (refereegranskat)abstract
- An understanding of the fracture aperture distribution facilitates design of grouting measures in crystalline rock masses, this since both the penetrability (ability of grout to enter the fractures) and penetration length is linked to the aperture. This is considered in a design process for rock grouting that has been developed at Chalmers University of Technology. The process suggests that fracture aperture distribution can be estimated based on transmissivity data from hydraulic tests combined with fracture data from boreholes. However, hydraulic tests seldom contain information that can be linked to individual fractures and measurement data need to be further processed using probability distributions. To resemble a rock mass where few fractures dominate the flow Fransson suggested the use of a Pareto distribution and combinatorics to estimate transmissivity of individual fractures. A freely available computational tool for the statistical analyses based on this concept with Pareto distributed fractures was developed previously. The purpose of the tool is to process field data and create probability distributions that can be used as input to grouting design and approximate tunnel leakage estimates. The methodology has been developed with tunnel data, which sofar has been the main application. For dam and open cut grouting, with higher proportions of surficial rock the validity of the connectivity assumptions may need to be investigated. This paper briefly present the design process and calculation tool in its context using real datasets from a Swedish tunneling project, to provide advice on usage and to give examples of pitfalls in data collection.
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| 8. |
- Thörn, Johan, 1986, et al.
(författare)
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Hydraulic and Hydromechanical Laboratory Testing of Large Crystalline Rock Cores
- 2015
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Ingår i: Rock Mechanics and Rock Engineering. - : Springer Science and Business Media LLC. - 1434-453X .- 0723-2632. ; 48:1, s. 61-73
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, fracture stiffness in rock samples is determined by means of hydromechanical (HM) laboratory testing. The aim is threefold: to develop a procedure for sampling, to update testing equipment and to relate fracture stiffness to the geological history (e.g. stress history and fracture infillings). The hydraulic properties of twenty rock cores (diameter 190 mm, c. 100 mm high) from the Äspö Hard Rock Laboratory (HRL) were tested in a permeameter cell under different isotropic pressures up to 2.5 MPa. The flow rate through individual fracture samples was recorded. Four of the samples were re-tested in the permeameter cell using an updated hydromechanical procedure with deformation measurement across the fracture. Four load cycles of gradually increasing cell pressure were applied, resulting in a clearly observed hysteresis effect in the first and second cycles. Hydraulic aperture changes calculated using the cubic law were compared with their mechanical equivalents. The aperture changes followed similar trends, although these differed between the samples. Fracture stiffness was determined from the tests and the stiffness to hydraulic aperture relationship was found to follow previously published patterns linked to the storativity of fractures. Differences in stiffness are explained in the context of the geological history of individual samples, particularly their stress history. The paper presents a conceptualisation of the stiffness behaviour, which includes flow properties, geometric properties and the geological stress history of the tested samples.
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| 9. |
- Thörn, Johan, 1986
(författare)
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The Impact of Fracture Geometry on the Hydromechanical Behaviour of Crystalline Rock
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Effective construction of tunnels in fractured crystalline rock requires a unified approach for handling rock mechanics and hydrogeological issues. Traditionally, rock mechanics and hydrogeology not only use different nomenclature, they also measure parameters such as e.g. aperture differently. A description of fractures that includes both fracture surface- and void geometry could be used as a basis for a conceptual model that allows complexity to be added to the descriptions of hydraulic and mechanical behaviour without contradictions. In this work, hydromechanically coupled experimental setups and methods were developed and used to improve a conceptual model of hydromechanical (HM) fracture behaviour at low compressive stress. Key aspects of the model are hydraulic aperture, fracture normal stiffness, the number of contacts between the surfaces, and the aspect ratio, i.e. the relationship between contact point distance and aperture, thus describing the voids between the surfaces. The experimental setups that were developed comprised equipment for in situ measurements of mechanical deformation due to stepwise hydraulic injection of fractures close to a tunnel, and a laboratory HM permeameter used in conjunction with fracture topography and aperture scanning. The latter produced high-resolution aperture maps of samples at 1.0 MPa, which were related to the flow rates, estimated hydraulic aperture and stiffness from the HM permeameter tests of the samples. Aiming at a common aperture-stiffness relationship for laboratory and in situ tests at different scales, the results were compared to a previously suggested relationship linking hydraulic aperture and normal stiffness. A relationship that has been devised from in situ hydraulic interference tests and is assumed to be valid for low comp-ressional stress across fractures with limited prior deformation. The few laboratory samples tested and the in situ tests performed show agreement with the aperture-stiffness relationship. A relationship and a conceptual model that have potential to provide support to future studies on hydromechanical behaviour of crystalline rock.
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