| 1. |
- Mathern, Alexandre, 1986, et al.
(författare)
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Concrete Support Structures for Offshore Wind Turbines: Current Status, Challenges, and Future Trends
- 2021
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 14:7
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Forskningsöversikt (refereegranskat)abstract
- Today’s offshore wind turbine support structures market is largely dominated by steel structures, since steel monopiles account for the vast majority of installations in the last decade and new types of multi-leg steel structures have been developed in recent years. However, as wind turbines become bigger, and potential sites for offshore wind farms are located in ever deeper waters and ever further from the shore, the conditions for the design, transport, and installation of support structures are changing. In light of these facts, this paper identifies and categorizes the challenges and future trends related to the use of concrete for support structures of future offshore wind projects. To do so, recent advances and technologies still under development for both bottom-fixed and floating concrete support structures have been reviewed. It was found that these new developments meet the challenges associated with the use of concrete support structures, as they will allow the production costs to be lowered and transport and installation to be facilitated. New technologies for concrete support structures used at medium and great water depths are also being developed and are expected to become more common in future offshore wind installations. Therefore, the new developments identified in this paper show the likelihood of an increase in the use of concrete support structures in future offshore wind farms. These developments also indicate that the complexity of future support structures will increase due to the development of hybrid structures combining steel and concrete. These evolutions call for new knowledge and technical know-how in order to allow reliable structures to be built and risk-free offshore installation to be executed.
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| 2. |
- Sundell, Jonas, 1984, et al.
(författare)
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Comprehensive risk assessment of groundwater drawdown induced subsidence
- 2019
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Ingår i: Stochastic Environmental Research and Risk Assessment. - : Springer Science and Business Media LLC. - 1436-3240 .- 1436-3259. ; 33:2, s. 427-449
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Tidskriftsartikel (refereegranskat)abstract
- © 2019, The Author(s). We present a method for risk assessment of groundwater drawdown induced land subsidence when planning for sub-surface infrastructure. Since groundwater drawdown and related subsidence can occur at large distances from the points of inflow, the large spatial extent often implies heterogeneous geological conditions that cannot be described in complete detail. This calls for estimation of uncertainties in all components of the cause-effect chain with probabilistic methods. In this study, we couple four probabilistic methods into a comprehensive model for economic risk quantification: a geostatistical soil-stratification model, an inverse calibrated groundwater model, an elasto-plastic subsidence model, and a model describing the resulting damages and costs on individual buildings and constructions. Groundwater head measurements, hydraulic tests, statistical analyses of stratification and soil properties and an inventory of buildings are inputs to the models. In the coupled method, different design alternatives for risk reduction measures are evaluated. Integration of probabilities and damage costs result in an economic risk estimate for each alternative. Compared with the risk for a reference alternative, the best prior alternative is identified as the alternative with the highest expected net benefit. The results include spatial probabilistic risk estimates for each alternative where areas with significant risk are distinguished from low-risk areas. The efficiency and usefulness of this modelling approach as a tool for communication to stakeholders, decision support for prioritization of risk reducing measures, and identification of the need for further investigations and monitoring are demonstrated with a case study of a planned railway tunnel in Varberg, Sweden.
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| 3. |
- Sundell, Jonas, 1984, et al.
(författare)
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Economic valuation of hydrogeological information when managing groundwater drawdown
- 2019
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Ingår i: Hydrogeology Journal. - : Springer Science and Business Media LLC. - 1431-2174 .- 1435-0157. ; 27:4, s. 1111-1130
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Tidskriftsartikel (refereegranskat)abstract
- © 2019, The Author(s). A procedure is presented for valuation of information analysis (VOIA) to determine the need for additional information when assessing the effect of several design alternatives to manage future disturbances in hydrogeological systems. When planning for groundwater extraction and drawdown in areas where risks—such as land subsidence, wells running dry and drainage of streams and wetlands—are present, the need for risk-reducing safety measures must be carefully evaluated and managed. The heterogeneity of the subsurface calls for an assessment of trade-offs between the benefits of additional information to reduce the risk of erroneous decisions and the cost of collecting this information. A method is suggested that combines existing procedures for inverse probabilistic groundwater modelling with a novel method for VOIA. The method results in (1) a prior analysis where uncertainties regarding the efficiency of safety measures are estimated, and (2) a pre-posterior analysis, where the benefits of expected uncertainty reduction deriving from additional information are compared with the costs for obtaining this information. In comparison with existing approaches for VOIA, the method can assess multiple design alternatives, use hydrogeological parameters as proxies for failure, and produce spatially distributed VOIA maps. The method is demonstrated for a case study of a planned tunnel in Stockholm, Sweden, where additional investigations produce a low number of benefits as a result of low failure rates for the studied alternatives and a cause-effect chain where the resulting failure probability is more dependent on interactions within the whole system rather than on specific features.
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| 4. |
- van Eldert, Jeroen, 1987-, et al.
(författare)
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Application of Measurement While Drilling Technology to Predict Rock Mass Quality and Rock Support for Tunnelling
- 2020
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Ingår i: Rock Mechanics and Rock Engineering. - : Springer. - 0723-2632 .- 1434-453X. ; 53:3, s. 1349-1358
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Tidskriftsartikel (refereegranskat)abstract
- A tunnelling project is normally initiated with a site investigation to determine the in situ rock mass conditions and to generate the basis for the tunnel design and rock support. However, since site investigations often are based on limited information (surface mapping, geophysical profiles, few bore holes, etc.), the estimation of the rock mass conditions may contain inaccuracies, resulting in underestimating the required rock support. The study hypothesised that these inaccuracies could be reduced using Measurement While Drilling (MWD) technology to assist in the decision-making process. A case study of two tunnels in the Stockholm bypass found the rock mass quality was severely overestimated by the site investigation; more than 45% of the investigated sections had a lower rock mass quality than expected. MWD data were recorded in 25 m grout holes and 6 m blast holes. The MWD data were normalised so that the long grout holes with larger hole diameters and the shorter blast holes with smaller hole diameters gave similar results. With normalised MWD data, it was possible to mimic the tunnel contour mapping; results showed good correlation with mapped Q-value and installed rock support. MWD technology can improve the accuracy of forecasting the rock mass ahead of the face. It can bridge the information gap between the early, somewhat uncertain geotechnical site investigation and the geological mapping done after excavation to optimise rock support.
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| 5. |
- Löfgren, Simon
(författare)
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Set-Based Design of Frame Bridges - Development and Implementation
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The traditional design process of bridges in structural engineering is based on the design approach called Point-Based design. To minimize environmental impact and industrialize the design process, the theory of Set-Based design (SBD) has been recognized as a promising approach. Since frame bridges is one of the most common bridge types in Sweden, the main objective of this thesis is to develop and implement a SBD tool for frame bridges. To be able to evaluate the different design alternatives generated by the design tool, evaluation criteria within buildability and sustainability are identified. Buildability is a concept within building industry that aims to improve productivity and safety within on-site production while also reducing the costs of the construction process. The building industry is one of the major contributors regarding impact on its surrounding. Therefore, there is a huge potential in improving the sustainability within the building industry. Sustainability is divided in Environment, Social and Economy aspects. The design tool allows performing an automated and iterative structural preliminary design of several frame bridge alternatives specified within ranges of design parameters. The design alternatives are analyzed with Finite Element Analysis (FEA) and evaluated according to predefined evaluation criteria. By scripting the design tool in programing language Python, it is possible to control an FEA program, such as Brigade Plus, from the design tool as well as performing a preliminary design of frame bridges. The preliminary design is performed according to requirements in national building codes, Eurocode. Finally, a case study is performed to investigate how a SBD tool can be implemented in an infrastructure project containing several frame bridges. In a large infrastructure project and with a SBD tool it is possible to find one optimum bridge solution that fulfills the need of several bridges in a set of bridges. The contractor can then industrialize parts of the construction of frame bridges, hopefully leading to a more sustainable and cost-effective building of frame bridges.
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| 6. |
- 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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| 7. |
- Acuña, José, 1982-
(författare)
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Distributed thermal response tests : New insights on U-pipe and Coaxial heat exchangers in groundwater-filled boreholes
- 2013
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Konstnärligt arbete (övrigt vetenskapligt/konstnärligt)abstract
- U-pipe Borehole Heat Exchangers (BHE) are widely used today in ground source heating and cooling systems in spite of their less than optimal performance. This thesis provides a better understanding on the function of U-pipe BHEs and Investigates alternative methods to reduce the temperature difference between the circulating fluid and the borehole wall, including one thermosyphon and three different types of coaxial BHEs.Field tests are performed using distributed temperature measurements along U-pipe and coaxial heat exchangers installed in groundwater filled boreholes. The measurements are carried out during heat injection thermal response tests and during short heat extraction periods using heat pumps. Temperatures are measured inside the secondary fluid path, in the groundwater, and at the borehole wall. These type of temperature measurements were until now missing.A new method for testing borehole heat exchangers, Distributed Thermal Response Test (DTRT), has been proposed and demonstrated in U-pipe, pipe-in-pipe, and multi-pipe BHE designs. The method allows the quantification of the BHE performance at a local level.The operation of a U-pipe thermosyphon BHE consisting of an insulated down-comer and a larger riser pipe using CO2 as a secondary fluid has been demonstrated in a groundwater filled borehole, 70 m deep. It was found that the CO2 may be sub-cooled at the bottom and that it flows upwards through the riser in liquid state until about 30 m depth, where it starts to evaporate.Various power levels and different volumetric flow rates have been imposed to the tested BHEs and used to calculate local ground thermal conductivities and thermal resistances. The local ground thermal conductivities, preferably evaluated at thermal recovery conditions during DTRTs, were found to vary with depth. Local and effective borehole thermal resistances in most heat exchangers have been calculated, and their differences have been discussed in an effort to suggest better methods for interpretation of data from field tests.Large thermal shunt flow between down- and up-going flow channels was identified in all heat exchanger types, particularly at low volumetric flow rates, except in a multi-pipe BHE having an insulated central pipe where the thermal contact between down- and up-coming fluid was almost eliminated.At relatively high volumetric flow rates, U-pipe BHEs show a nearly even distribution of the heat transfer between the ground and the secondary fluid along the depth. The same applies to all coaxial BHEs as long as the flow travels downwards through the central pipe. In the opposite flow direction, an uneven power distribution was measured in multi-chamber and multi-pipe BHEs.Pipe-in-pipe and multi-pipe coaxial heat exchangers show significantly lower local borehole resistances than U-pipes, ranging in average between 0.015 and 0.040 Km/W. These heat exchangers can significantly decrease the temperature difference between the secondary fluid and the ground and may allow the use of plain water as secondary fluid, an alternative to typical antifreeze aqueous solutions. The latter was demonstrated in a pipe-in-pipe BHE having an effective resistance of about 0.030 Km/W.Forced convection in the groundwater achieved by injecting nitrogen bubbles was found to reduce the local thermal resistance in U-pipe BHEs by about 30% during heat injection conditions. The temperatures inside the groundwater are homogenized while injecting the N2, and no radial temperature gradients are then identified. The fluid to groundwater thermal resistance during forced convection was measured to be 0.036 Km/W. This resistance varied between this value and 0.072 Km/W during natural convection conditions in the groundwater, being highest during heat pump operation at temperatures close to the water density maximum.
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| 8. |
- 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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| 9. |
- 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.
-
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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| 10. |
- Norrman, Jenny, 1971, et al.
(författare)
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Integration of the subsurface and the surface sectors for a more holistic approach for sustainable redevelopment of urban brownfields
- 2016
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 563, s. 879-889
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a holistic approach to sustainable urban brownfield redevelopment where specific focus is put on the integration of a multitude of subsurface qualities in the early phases of the urban redevelopment pro- cess, i.e. in the initiative and plan phases. Achieving sustainability in brownfield redevelopment projects may be constrained by a failure of engagement between two key expert constituencies: urban planners/designers and subsurface engineers, leading to missed opportunities and unintended outcomes in the plan realisation phase. A more integrated approach delivers greater benefits. Three case studies in the Netherlands, Belgium and Sweden were used to test different sustainability assessment instruments in terms of the possibility for knowl- edge exchange between the subsurface and the surface sectors and in terms of cooperative learning among experts and stakeholders. Based on the lessons learned from the case studies, a generic decision process frame- work is suggested that supports holistic decision making. The suggested framework focuses on stakeholder involvement, communication, knowledge exchange and learning and provides an inventory of instruments that can support these processes.
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| 11. |
- Darabi, H., et al.
(författare)
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Development of a novel hybrid multi-boosting neural network model for spatial prediction of urban flood
- 2021
-
Ingår i: Geocarto International. - : Taylor and Francis Ltd.. - 1010-6049 .- 1752-0762.
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, a new hybridized machine learning algorithm for urban flood susceptibility mapping, named MultiB-MLPNN, was developed using a multi-boosting technique and MLPNN. The model was tested in Amol City, Iran, a data-scarce city in an ungauged area which is prone to severe flood inundation events and currently lacks flood prevention infrastructure. Performance of the hybridized model was compared with that of a standalone MLPNN model, random forest and boosted regression trees. Area under the curve, efficiency, true skill statistic, Matthews correlation coefficient, misclassification rate, sensitivity and specificity were used to evaluate model performance. In validation, the MultiB-MLPNN model showed the best predictive performance. The hybridized MultiB-MLPNN model is thus useful for generating realistic flood susceptibility maps for data-scarce urban areas. The maps can be used to develop risk-reduction measures to protect urban areas from devastating floods, particularly where available data are insufficient to support physically based hydrological or hydraulic models.
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| 12. |
- Javed, Saqib, 1978
(författare)
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Development of Modelling and Simulation tools for Geothermal Basements and Deep Foundations in Soft Clays
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Pile heat exchangers are fast emerging as a potentially viable alternative to the more prevalent borehole heat exchangers for the provision of space heating and cooling. In the last decade or so, the use of geothermal piles has increased sharply in many countries including Belgium, China, Japan, Switzerland, the Netherlands, United Kingdom, and United States, among others. In Sweden, however, interest in geothermal piles has been surprisingly scant. This is despite the fact that most of the infrastructure and buildings in Sweden are founded on piled foundations. Early estimates suggest that approximately 75 % of heating requirements and 90 % of cooling requirements of a typical Swedish office building could be provided by geothermal piles. Initial studies also indicate quick payback and large carbon savings. On the other hand, as several Swedish cities are founded in areas with very soft soil conditions with high groundwater tables, there are concerns that pile heat exchangers with cyclic thermal loading could trigger excessive creep deformations. Most of the Swedish research on geothermal piles and cyclic thermal loading dates back to 1980s. Today, both analysis and test methods for understanding soft clay behaviour have improved significantly. Hence, there is a need to revisit the topic of cyclic heating and cooling of Swedish soft clays to fully understand the implications of the use of geothermal piles.This project, funded by Swedish Energy Agency, has dealt with the development of mathematical models for thermal modelling of geothermal piles in Swedish soft clay conditions. The new models include a method to determine the thermal impact of the building on the underlying pile heat exchangers, and calculation methods to evaluate the thermal resistance of the pile heat exchangers. An existing borehole model has also been updated for modelling of irregular configurations of geothermal piles. The mathematical models developed in this project can be implemented in any computer code to be incorporated in existing building energy simulation software. The models can also be used to develop controllers and control schemes to maximize the performance of pile heat exchangers. The project has also demonstrated the application of driven steel and precast pile heat exchangers in Swedish soft clays and has established the importance of acquiring in-situ measurements to determine key design parameters. The results from the project have been presented in seven journal and conference proceeding papers, three research reports, and one book chapter.
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| 13. |
- Karlsson, Mats, 1974, et al.
(författare)
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Consequences of sample disturbance when predicting long-term settlements in soft clay
- 2016
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Ingår i: Canadian Geotechnical Journal. - : Canadian Science Publishing. - 1208-6010 .- 0008-3674. ; 53:12, s. 1965-1977
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Tidskriftsartikel (refereegranskat)abstract
- An approach for assessing the effects of sample quality is presented. Soil samples were taken using a 50 mm Swedish STII piston sampler and the Norwegian University of Science and Technology (NTNU) mini-block sampler from a soft clay test site. Differences in laboratory test results are identified for several stress paths, assisted by simulations made using an advanced constitutive model. Hitherto such comparisons have focused on differences in basic engineering properties such as strength and stiffness. The effect of choosing alternative model parameters from piston and block samples is demonstrated through the analysis of the long-term settlement of an embankment. The simulations show that substantially larger settlements and lateral displacements are predicted using parameters obtained from the piston samples. Furthermore, the magnitude of the differences is larger than expected. This demonstrates that for this application, relatively small differences in the assessed sample quality, using traditional laboratory data interpretation methods, are amplified when applied to a prototype boundary value problem. It is suggested that a little more care in sampling and testing can result in large cost savings as a result of the more reliable model parameters that can be extracted, particularly when the improved sampling is combined with the use of an advanced constitutive model.
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| 14. |
- Persson, Peter, et al.
(författare)
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Effect of structural design on traffic-induced building vibrations
- 2017
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Ingår i: Procedia Engineering. - : Elsevier BV. - 1877-7058. ; 199, s. 2711-2716
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Tidskriftsartikel (refereegranskat)abstract
- Population growth and urbanization results in densified cities, where new buildings are being built closer to existing vibration sources, and new transportation systems are constructed closer to existing buildings. Potential disturbing vibrations are one issue to consider in planning urban environments and densification of cities. Vibrations can be annoying for humans but also for sensitive equipment in, for example, hospitals. In determining the risk for disturbing vibrations, the distance between the source and the receiver, the ground properties, and type and size of the building are governing factors. In the paper, a study is presented aiming at investigating the influence of various parameters of the building’s structural design on vibration levels in the structure caused by ground surface loads, e.g. traffic. Parameters studied are related to the type of construction material (if it would be a light or heavy structure), and to the slab thickness. The study is limited to the structural response at frequencies near the first resonance frequency of the soil. The finite element method is employed for discretizing the building structure that is coupled to a semi-analytical model considering a layered ground.
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| 15. |
- Bin, Jiang, 1965-, et al.
(författare)
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Automatic generation of the axial lines of urban environments to capture what we perceive
- 2010
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Ingår i: International Journal of Geographical Information Science. - London : Taylor & Francis Group. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 24:4, s. 545-558
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Tidskriftsartikel (refereegranskat)abstract
- Based on the concepts of isovists and medial axes, we developed a set of algorithms that can automatically generate axial lines for representing individual linearly stretched parts of open space of an urban environment. Open space is the space between buildings, where people can freely move around. The generation of the axial lines has been a key aspect of space syntax research, conventionally relying on hand-drawn axial lines of an urban environment, often called axial map, for urban morphological analysis. Although various attempts have been made towards an automatic solution, few of them can produce the axial map that consists of the least number of longest visibility lines, and none of them really works for different urban environments. Our algorithms provide a better solution than existing ones. Throughout this paper, we have also argued and demonstrated that the axial lines constitute a true skeleton, superior to medial axes, in capturing what we perceive about the urban environment.
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| 16. |
- Bin, Jiang, 1965-, et al.
(författare)
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Computing the fewest-turn map directions based on the connectivity of natural roads
- 2011
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Ingår i: International Journal of Geographical Information Science. - London : Taylor & Francis Group. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 25:7, s. 1069-1082
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we introduced a novel approach to computing the fewest-turn map directions or routes based on the concept of natural roads. Natural roads are joined road segments that perceptually constitute good continuity. This approach relies on the connectivity of natural roads rather than that of road segments for computing routes or map directions. Because of this, the derived routes posses the fewest turns. However, what we intend to achieve are the routes that not only possess the fewest turns, but are also as short as possible. This kind of map direction is more effective and favorable by people, because they bear less cognitive burden. Furthermore, the computation of the routes is more efficient, since it is based on the graph encoding the connectivity of roads, which is significantly smaller than the graph of road segments. We made experiments applied to eight urban street networks from North America and Europe in order to illustrate the above stated advantages. The experimental results indicate that the fewest-turn routes posses fewer turns and shorter distances than the simplest paths and the routes provided by Google Maps. For example, the fewest-turn-and-shortest routes are on average 15% shorter than the routes suggested by Google Maps, while the number of turns is just half as much. This approach is a key technology behind FromToMap.org - a web mapping service using openstreetmap data.
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| 17. |
- 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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| 18. |
- 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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| 19. |
- 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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| 20. |
- Persson, Peter
(författare)
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Vibrations in a Built Environment : Prediction and Reduction
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Vibrations in a built environment can exceed the requirements for sensitive equipment in a building or can cause annoyance to residents. Hence, there is often a need for reducing such vibrations. The vibrations can originate from ambient sources such as motorway traffic, or from internal sources such as people walking inside the building. Disturbing vibrations can be reduced by reduction measures. Vibration-reduction measures can be evaluated numerically, with for instance the finite element method, to avoid construction of expensive mock-ups. In the thesis, large finite element models involving several physical domains (e.g. road, soil, bedrock, and building parts) were developed to study the effect of vibration-reduction measures.Ground vibrations can be reduced by installing a wave barrier between an external source and a receiver. As concluded in the thesis, an empty barrier (i.e. a trench) installed in the soil has the ability to reduce the ground-vibration level by approximately 60%. If the barrier contains a solid material, however, the level of reduction is reduced to approximately 30%. At long distances, at around 500 m and longer, from the vibration source, an amplification in vibration is observed. At such distances, moreover, the ground motion follows the motion of the bedrock. Another example of a wave obstacle that is studied in the thesis involves shaping the landscape surrounding a building. The topsoil that is usually transported from the construction site can be used to construct hills and valleys that constitute the shaped landscape. However, this can result in anything from an appreciable reduction to an appreciable amplification in the ground-vibration levels, depending on how the landscape is formed. If constructed properly, the reduction in the level of vibration can reach approximately 35%. Vibrations from both external and internal sources can be reduced by modifying the properties of the concrete slabs and the soil underneath. The soil properties can be improved by mixing the soil with a binder, in order to stiffen the soil. Is is shown in the thesis that by using stabilised soil underneath a concrete slab, vibrations originating from motorway traffic can be reduced by almost 60%, and up to 80% for an internal pedestrian load. By using a time-efficient numerical model developed in the thesis, the effect by using different positions for the supports of a water-pipe system on vibrations transmitted to other parts of buildings was studied. Because frequency peaks can be avoided, a marked change of vibration characteristics can be achieved. A reduction of more than 60% in the transmitted vibrations was observed. The general methods and measures presented in the thesis are exemplified by the conceptual design process of the MAX IV Laboratory, a vibration-sensitive research facility. This laboratory exhibited the phenomena needed for selecting it as a comprehensive example case.
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| 21. |
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Proceedings of the 14th ICOLD International Benchmark Workshop on Numerical Analysis of Dams
- 2017
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Proceedings (redaktörskap) (refereegranskat)abstract
- Every second year, the Technical Committee A (Computational Aspects of Dam Analysis and Design) of ICOLD organizes an international benchmark workshop on numerical analysis of dams. The purpose is to share knowledge and experience regarding numerical modelling within the fields of dam safety, planning, design, construction as well as operation and maintenance of dams. The Terms of Reference for Committee A state; ”BenchmarkWorkshops are organised to compare numerical models between one another and/or with reference solutions, including the dissemination and publication of results”. The 14th ICOLD International Benchmark Workshop on Numerical Analysis of Dams was held from the 6th to the 8th September 2017 in Stockholm, the capital of Sweden. It was organized by the Local Organizing Committee, on behalf of the Swedish National Committee of ICOLD (SwedCold) and the ICOLD Technical Committee A. It was hosted by KTH Royal Institute of Technology, Sweden’s largest technical research and learning institution and one of Europe’s leading technical universities. With respect to hydropower and dam engineering, KTH has for many years been active within of the Swedish hydropower Center (SVC), a key centre for research and educational activities in Sweden. SwedCOLD established in 1931, and is one of the oldest members of the International Commission On Large Dams, ICOLD. The development of hydro power for electricity production was initiated in the late 19th century and made the large scale industrialisation in Sweden possible. About 2000 hydropower plants are in operation in Sweden today, producing almost half of the total electricity supply. Considering the many and relatively old dams in Sweden, organizing the benchmark workshop was important to increase the knowledge regarding managing aging hydropower structures.The 14th ICOLD International Benchmark Workshop has addressed current challenges regarding design and maintenance of existing dams and improved the understanding of these by exchange of experience on the use of numerical modelling for design, performance evaluation and safety assessment of dams. On behalf of the organizing committee, I would like to express my sincere appreciation to the formulators/moderators of each theme for their outstanding work to prepare the themes, reviewing the papers and evaluating the results. I also want to thank all participants to the benchmark workshop for their contributions and their presence to this benchmark workshop. Finally, the support from the Technical Committee A and the support from the companies and organizations that sponsored this benchmark workshop is gratefully acknowledged.
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| 22. |
- Theland, Freddie, 1989-, et al.
(författare)
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Dynamic response of driven end-bearing piles and a pile group in soft clay: an experimental validation study
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents an extensive measurement campaign of the dynamic response of driven end-bearing piles and a pile group in soft clay. Results from measurements conducted on the free-top piles and and the piles joined in a concrete cap are presented. The measured frequency responses are subsequently used to obtain the impedances, characterising the dynamic stiffness and damping of the piles and the pile foundation. The piles are instrumented with accelerometers at several points along the length of the piles which allows to validate the dynamic motion of the piles atdepth due to pile head and pile cap excitation. Numerical predictions based solely on information of the small-strain soil properties obtained from extensive site investigations are compared to the experimental results. The numerical model captures the pile-soil-pile interactions and the motion of the piles within the soil well, suggesting that reliable predictions can be made for the considered soil conditions if the small-strain soil properties are well known.
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| 23. |
- 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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| 24. |
- Billberg, Ingmar, 1946-2005
(författare)
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Prestigefyllt broprojekt
- 1991
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Ingår i: Kulturmiljövård. - Stockholm : Riksantikvarieämbetet. - 1100-4800. ; [16]:2, s. 55-56
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 25. |
- 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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