| 1. |
- Mathern, Alexandre, 1986, et al.
(författare)
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Experimental study of time-dependent properties of a low-pH concrete for deposition tunnels
- 2018
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Ingår i: fib Symposium. - 2617-4820. ; , s. 1726-1735
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Konferensbidrag (refereegranskat)abstract
- The Swedish Nuclear Fuel and Waste Management Company developed a method for the final disposal of canisters for spent nuclear fuel in tunnels at depths of about 500 meters. The concept for closure of the deposition tunnels is based on a bentonite seal supported by a spherical concrete dome structure. In order to fulfil the requirements specific to the repository concept, a special mix of low-pH self-compacting concrete was developed. A series of large-scale castings and laboratory tests were conducted to gain experience on this low-pH concrete mix, in conjunction with the full-scale demonstration test of an unreinforced concrete dome plug in the underground hard rock laboratory in Äspö, Sweden. The laboratory tests aimed at studying the creep properties under high sustained compressive stresses of the low-pH concrete mix, its shrinkage properties and the properties of the rock-concrete interface. This paper provides an overview of these tests and analyses the latest results of the recently completed creep tests, which include 6 years of measurements. These results allow to improve understanding of the structural behaviour of the concrete plug and to assess the effects of the very high pressure acting on the plug on its deformations, cracking and water tightness.
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| 2. |
- Garmabaki, Amir H. Soleimani, et al.
(författare)
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A Survey on Underground Pipelines and Railway Infrastructure at Cross-Sections
- 2019
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Ingår i: Proceedings of the 29th European Safety and Reliability Conference (ESREL 2019). - Singapore : Research Publishing Services. ; , s. 1094-1101
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Konferensbidrag (refereegranskat)abstract
- Underground pipelines are an essential part of the transportation infrastructure. The structural deterioration of pipelines crossing railways and their subsequent failures are critical for society and industry resulting in direct and indirect costs for all the related stakeholders. Pipeline failures are complex processes, which are affected by many factors, both static (e.g., pipe material, size, age, and soil type) and dynamic (e.g., traffic load, pressure zone changes, and environmental impacts). These failures have serious impacts on public due to safety, disruption of traffic, inconvenience to society, environmental impacts and shortage of resources. Therefore, continuous and accurate condition assessment is critical for the effective management and maintenance of pipeline networks within transportation infrastructure. The aim of this study is to identify failure modes and consequences related to the crossing of pipelines in railway corridors. Expert opinion have been collected through two set of questionnaires which have been distributed to the 291 municipalities in the whole Sweden. The failure analysis revealed that pipe deformation has higher impact followed by pipe rupture at cross-section with railway infrastructure. For underground pipeline under railway infrastructure, aging and external load gets higher ranks among different potential failure causes to the pipeline.
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| 3. |
- Iupikov, Oleg, 1983, et al.
(författare)
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The Hybrid Chamber for OTA measurements: Plane Wave Spectrum Quality Vs. Dynamic Range Trade-off
- 2022
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Ingår i: 2022 16th European Conference on Antennas and Propagation, EuCAP 2022.
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Konferensbidrag (refereegranskat)abstract
- In this paper, the trade-off between the quality of the plane wave spectrum synthesized in the test zone of the hybrid over-the-air (OTA) chamber and factors affecting the dynamic range of this measurement system is investigated. The hybrid chamber performance is compared to a plane wave generator (PWG) in free space. The performance evaluation is focused on the field radiated into the test zone (TZ) while maintaining its quality according to 3GPP specification. It is demonstrated that a good quality can be achieved for the synthesized plane wave spectrum.
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| 4. |
- Norrman, Jenny, 1971, et al.
(författare)
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The significance of planning and management of the subsurface to achieve sustainable cities
- 2020
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: The subsurface is the foundation upon which all cities rest. But the subsurface is not only a construction basis which provide physical space for infrastructure and the possibility to create a better surface living environment: the subsurface is a multifunctional natural resource. Apart from physical space, it provides water, energy, materials, habitats for ecosystems, support for surface life, and a repository for cultural heritage and geological archives. Currently, the subsurface is often utilised according to the “first-come-first-served” principle, which hinders possibilities to take strategic decisions on prioritisation and optimisation of competing subsurface uses, as well as fair inter- and intragenerational distribution of limited natural resources. A great disadvantage is the invisibility of the subsurface and consequently a lack of understanding of it as a multifunctional resource: the recently launched concept of geosystem services could help mitigate its underrating. Methods: In order to better acknowledge and lift forward the significance of the subsurface in achieving a sustainable future, the 17 SDGs are scrutinized in relation to the resources of subsurface, and specifically how better planning and management of the subsurface can contribute in achieving the goals. Results: Subsurface planning and management is relevant to at least seven (3, 6, 7, 9, 11, 12, 13) out of seventeen SDGs. Although the subsurface is not explicitly mentioned in the SDGs (except for aquifers), the subsurface can significantly contribute in achieving several of these goals. Conclusions: Sound planning and management of the subsurface can support the achievement of the mapped SDGs in various ways. The subsurface must be recognised as a precious and multifunctional resource which require careful planning and sensitive management in accordance with its potential and its value to society. Grant support: Swedish Research Council Formas (942-2016-50), Swedish Rock Engineering Research Foundation (BeFo 385), Swedish Institute Visby Programme (23887/2017).
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| 5. |
- Hazarika, Amrita, 1993, et al.
(författare)
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Reactivity of Mixed Layer Clays – The Effect of Polycarboxylate Based Superplasticizers on Effective Particle Size Distributions
- 2023
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Ingår i: RILEM Bookseries. - 2211-0844 .- 2211-0852. ; 44, s. 300-310
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Konferensbidrag (refereegranskat)abstract
- The declining availability of promising supplementary cementitious materials (SCMs) in the recent past, such as fly ash and ggbfs, has opened new recesses in the domain of alternative binders. It is therefore imperative and urgent to develop more lasting and consistent alternatives, for addressing the need to diminish the carbon footprint of cement production. The potentialities of utilizing mixed layer excavated clays that are obtained as by-products of repair and construction activities, as possible SCMs have been well established in past literature. However, understanding the relationship between particle deagglomeration and pozzolanic properties via non-energy-intensive methods, is still an open niche yet to be fully explored. This study is an attempt at understanding the use of dispersive mechanisms such as super-plasticizers and storage in suspension to possibly impact surface charges of clay agglomerates and eventually, their reactivity. It is found that dispersive agents added to ground clay particles can enhance pozzolanicity of mixed layer clay particles and thereby reduce dependence on energy intensive methods such as grinding for activation.
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| 6. |
- Merisalu, Johanna, 1990, et al.
(författare)
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Hydrogeological reference conditions for assessment of environmental impact and for grouting design
- 2018
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Ingår i: ISRM International Symposium - 10th Asian Rock Mechanics Symposium, ARMS 2018.
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Konferensbidrag (refereegranskat)abstract
- Dewatering of groundwater resources induced by leakage into underground constructions can cause land subsidence, damage to constructions and their foundations and disturbances of groundwater dependent ecosystems. To reduce the environmental impacts, safety measures, e.g. sealing fractures by grouting to reduce inflow of groundwater or artificial recharge to maintain groundwater levels, must be implemented. Site investigations of the total geological and hydrogeological conditions at a site before construction is, due to financial aspects, most often not possible. To handle these uncertainties in the design- and construction process, it is suitable to use the observational method, which include the idea of identification, confirmation or rejection, and revision of the most probable and unfavorable conditions, and predefined technical design solutions for conditions that can reasonable be anticipated or foreseen. To assess the geological and hydrogeological conditions at an early stage of a project we suggest that geological and related hydrogeological reference conditions are used. Fundamental to our approach using reference conditions is the grouping of materials with similar geological and hydrogeological conditions and engineering characteristics. In this paper, we present conceptualizations of five reference conditions common in western Sweden and two examples of reference conditions in Singapore. The conceptualization of reference conditions includes a description of: the geological material; the hydrogeological properties and behavior within the environment; and the engineering characteristics related to water control and grouting. Examples of technical design solutions used to adopt to project specific requirements for inflow and drawdown for underground constructions constructed in environments representing one of the suggested reference conditions in western Sweden are also presented to exemplify the application of reference conditions for technical design.
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| 7. |
- Tornborg, Johannes, 1984, et al.
(författare)
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Benchmarking of a contemporary soil model for simulation of deep excavations in soft clay
- 2019
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Ingår i: Proceedings of the XVII European Conference on Soil Mechanics and Geotechnical Engineering. - 9789935943613
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Konferensbidrag (refereegranskat)abstract
- Measurement data from previous excavation works in soft clay deposits are revisited to benchmark a contemporary constitutive soil model, referred to as the Creep-SCLAY1S. The research is motivated by the planned deep excavations for the West Link tunnel in Gothenburg that require analyses of both short- and long-term performance. Unique data on prior excavation works, which were instrumented and monitored during the construction period, will be utilised. In contrast to previous studies, that focused on the construction period, also the long-term performance will be assessed using satellite data. The analyses are carried out using a contemporary rate-dependent model, considering the on-going (background) creep deformations in the clay deposit. The study shows that while the recent model developments result in improved predictions, additional features need to be further developed: most notably, the formulations for the rate-dependent small strain stiffness in loading and unloading stress paths requires attention. Also, it is evident that modelling details, such as installation effects (sheet pile wall and pre-cast concrete displacement piles) are important for prediction of the subsequent response.
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| 8. |
- Frischknecht, Rolf, et al.
(författare)
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Comparative Life Cycle Assessment of Geosyhnthetics versus Conventional filter layer
- 2013
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Ingår i: Proceedings of the 18th International Conference on Soil Mechanics and Geotechnical Engineering. - 9782859784744 ; 4, s. 3203-3206
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Konferensbidrag (refereegranskat)abstract
- Geosynthetics made from plastics can replace filter layers made of gravel. In this article goal and scope, basic data and the results of a comparative life cycle assessment of gravel and geosynthetics based filter layers are described. The filter layers of a road made of 30 cm gravel and a filter geosynthetic, respectively, form the basis for the comparison. The filter layers have the same technical performance and the same life time of 30 years. The product system includes the supply of the raw materials, the manufacture of the geotextiles and the extraction of mineral resources, the construction of the road filter, its use and its end of life phase. The life cycle assessment reveals that the geosynthetics based filter layer causes lower environmental impacts per square metre. The cumulative greenhouse gas emissions amount to 7.8 kg CO2-eq (mineral filter) and to 0.81 kg CO2-eq (geosynthetic filter). The variation of the thickness of the gravel based filter layer confirms the lower environmental impacts of a geosynthetics based filter layer. Environmental impacts of the geosynthetic production are dominated by the raw material provision (plastic granulate) and electricity consumption during manufacturing.
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| 9. |
- Hector, Johanna, et al.
(författare)
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Environmental emission impact from transport during soil remediation
- 2012
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Ingår i: Urban Environment. - 9789400725393 ; 19, s. 439-448
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Konferensbidrag (refereegranskat)abstract
- The Swedish Environmental Protection Agency has identified more than 80 000 potentially contaminated sites in Sweden. One of these is the “former Hexion site” in Mölndal, south of Gothenburg. The property was bought by the construction company NCC in order to build a new housing area. On the site industrial production has been performed for almost 200 years. The products have been chemicals, e g binders for the coatings industry and plastics additives like phthalates. Measured concentrations of pollutants exceed the EPA’s general guidelines on “sensitive land use” and a remediation is necessary.The aim of the present study has been to perform a life cycle assessment of the environmental impact caused by excavation, transports and purification in the remediation, comparing three remediation strategies: Insitu, Exsitu and Exsitu in combination with onsite. Four different options for transportation and receiver/treatment have been analyzed.Exsitu methods were found to cause a much larger environmental load than the insitu. Emissions from the remediation may be reduced by reducing the volume of contaminated soil before transport to landfill. This can be done by pre-treating the soil onsite with sifting or soil washing. Sea transport leads to a high environmental impact. Future reduction of emissions from shipping will make shipping a more competitive choice.
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| 10. |
- Wikby, Pierre, 1995, et al.
(författare)
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The influence of parameter variability on subsidence
- 2023
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Ingår i: 10th European Conference on Numerical Methods in Geotechnical Engineering. ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Leakage into rock tunnels covered by thick soft clay deposits may cause a pore water pressure drop over large areas through underdrainage, resulting in settlement problems and potential damage to structures. In urban areas, heterogeneity in soil properties can be substantial. In this paper, a case study with a systematic sensitivity analysis combined with coupled hydro-mechanical finite element analyses was performed for three key parameters (overconsolidation ratio, vertical hydraulic conductivity and hydraulic anisotropy) considering one scenario of underdrainage. The results show that both the magnitude and uncertainty of settlements are strongly stratigraphy-dependent. The overconsolidation ratio contributed the most to the settlement uncertainty and the effect of vertical hydraulic conductivity was also found to be significant, while the changes in hydraulic anisotropy had negligible influence.
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