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Concrete dams in cold regions are designed to resist static loads from the ice sheet forming on the reservoir. Current guidelines suggest design ice loads of 50-250 kN/m based solely on geographical location, overlooking site-specific conditions. For many dams, this constitutes a considerable part of the total horizontal load and could theoretically cause problems with stability, especially for lower dams. However, the knowledge about the actual magnitude of ice loads remains limited, and no stability failure initiated by ice loads has been reported. This paper presents results from ice load measurements using a 1 X 3 m2 load panel installed at two dams in Sweden. The results from ice load measurements are presented alongside external factors such as water level, ambient temperatures, precipitation, and ice thickness, offering a more comprehensive understanding of the variables affecting ice loads on concrete dams., QC 20241211, Forecasting of ice-loads on concrete dams

IMPORTANCE: The Targeted Hypothermia vs Targeted Normothermia After Out-of-Hospital Cardiac Arrest (TTM2) trial reported no difference in mortality or poor functional outcome at 6 months after out-of-hospital cardiac arrest (OHCA). This predefined exploratory analysis provides more detailed estimation of brain dysfunction for the comparison of the 2 intervention regimens. OBJECTIVES: To investigate the effects of targeted hypothermia vs targeted normothermia on functional outcome with focus on societal participation and cognitive function in survivors 6 months after OHCA. DESIGN, SETTING, AND PARTICIPANTS: This study is a predefined analysis of an international multicenter, randomized clinical trial that took place from November 2017 to January 2020 and included participants at 61 hospitals in 14 countries. A structured follow-up for survivors performed at 6 months was by masked outcome assessors. The last follow-up took place in October 2020. Participants included 1861 adult (older than 18 years) patients with OHCA who were comatose at hospital admission. At 6 months, 939 of 1861 were alive and invited to a follow-up, of which 103 of 939 declined or were missing. INTERVENTIONS: Randomization 1:1 to temperature control with targeted hypothermia at 33 °C or targeted normothermia and early treatment of fever (37.8 °C or higher). MAIN OUTCOMES AND MEASURES: Functional outcome focusing on societal participation assessed by the Glasgow Outcome Scale Extended ([GOSE] 1 to 8) and cognitive function assessed by the Montreal Cognitive Assessment ([MoCA] 0 to 30) and the Symbol Digit Modalities Test ([SDMT] z scores). Higher scores represent better outcomes. RESULTS: At 6 months, 836 of 939 survivors with a mean age of 60 (SD, 13) (range, 18 to 88) years (700 of 836 male [84%]) participated in the follow-up. There were no differences between the 2 intervention groups in functional outcome focusing on societal participation (GOSE score, odds ratio, 0.91; 95% CI, 0.71-1.17; P =

BACKGROUND: Low level of physical activity is a risk factor for new cardiac events in out-of-hospital cardiac arrest (OHCA) survivors. Physical activity can be assessed by self-reporting or objectively by accelerometery. AIM: To investigate the agreement between self-reported and objectively assessed physical activity among OHCA survivors HYPOTHESIS: Self-reported levels of physical activity will show moderate agreement with objectively assessed levels of physical activity. METHOD: Cross-sectional study including OHCA survivors in Sweden, Denmark, and the United Kingdom. Two questions about moderate and vigorous intensity physical activity during the last week were used as self-reports. Moderate and vigorous intensity physical activity were objectively assessed with accelerometers (ActiGraph GT3X-BT) worn upon the right hip for 7 consecutive days. RESULTS: Forty-nine of 106 OHCA survivors answered the two questions for self-reporting and had 7 valid days of accelerometer assessment. More physically active days were registered by self-report compared with accelerometery for both moderate intensity (median 5 [3:7] vs. 3 [0:5] days; p < 0.001) and vigorous intensity (1 [0:3] vs. 0 [0:0] days; p < 0.001). Correlations between self-reported and accelerometer assessed physical activity were sufficient (moderate intensity: rs = 0.336, p = 0.018; vigorous intensity: rs = 0.375, p = 0.008), and agreements were fair and none to slight (moderate intensity: k = 0.269, p = 0.001; vigorous intensity: k = 0.148, p = 0.015). The categorization of self-reported versus objectively assessed physical activity showed that 26% versus 65% had a low level of physical activity. CONCLUSION: OHCA survivors reported more physically active days compared with the results of the accelerometer assessment and correlated sufficiently and agreed fairly and none to slightly.

Dammhaverier är mycket ovanliga och därför är kunskapen om brottförloppet vid ett potentiellt dammbrott begränsad. Uppstår brottet utan förvarning, eller finns tidiga tecken på allvarliga problem? Hur utvecklas brottsbräschen under brottförloppet? Detta är frågor som blivit än mer aktuella efter tre internationella dammhaverier under 2023. För att söka svar har en serie skalmodellförsök utförts där haverier av betongdammar simuleras. En viktig parameter vid säkerhetsbedömningen av en betongdamm består i att utvärdera dess stabilitet. Förenklat görs dettag enom att jämföra om dammkroppens vikt är tillräcklig för att stå emot lasten från vattnets tryck. Traditionellt beaktas enbart en mindre del av en betongdamm när dess stabilitet utvärderas men de nya försöken indikerar att det vore eftersträvansvärt att undersöka hela dammen samtidigt eftersom lasten fördelas mellan konstruktionsdelarna. Många betongdammars tillstånd övervakas idag genom automatiska mätningarav till exempel vattenstånd, förskjutningar och grundvattentryck. Dock finns det ingen standardiserad metod för att definiera larmgränser,vilket detta projekt syftar till att utveckla i framtiden., QC 20240118

QC 20240115

Research on embankment dam monitoring was recently carried out at a test site in Sweden, with the objectives of: testing geophysical meth-ods of locating defects in the structure; and, using geotechnical instruments to check the behaviour of the dam during first impounding, and subsequently during fluctuations of the reservoir level. The main purpose was to investigate if conventional geophysical methods can be used to detect embedded faults at a rockfill embankment dam in a blind test. Initially, a number of scientists with different specializations in geophysical methods were invited to perform a synthetic pre-simulation assessement to determine if their non-destructive methods would reveal the defects. The test facility is described, the embankment dam constructed for the study and some highlights of the results., QC 20231212

Large volumes of steel fibre reinforced shotcrete (sprayed concrete) and steel bolts are commonly used to support tunnels in hard rock. This generates a high CO2-footprint which must be reduced in order to decelerate the continuously increasing average temperature worldwide caused by the emissions of greenhouse gases. Thus, alternative design methods and the possibility to use other materials than steel are currently investigated. Work is ongoing on testing the load-bearing capacity of shotcrete reinforced with fibres of steel, basalt and synthetic materials. This also includes a comparison between tests using Round Determinate Panels (RDP) and four-point bending of beams. Moreover, the practical use of RDP testing as a quality control methodology is also investigated in situ. Here, the goal is to identify several shotcrete mixes suitable for use in tunnelling so that the right material and fibre volume can be used in the right place., QC 20231023

Although the failure of a concrete dam is a complex and highly dynamic process, the current safety assessments of concrete gravity and buttress dams rely on a simplified 2D stability analysis, which neglects the load redistribution due to 3D monolith interactions and the valley shape. In addition, the estimation of breach parameters in concrete dams is based on assumptions rather than analyses, and better prediction methods are needed. Model tests have been conducted to increase the understanding of the failure behavior of concrete dams. A scale model buttress dam, with a scale of 1:15, consisting of 5 monoliths that were 1.2 m in height and 4 m in width, was constructed and loaded to failure using water pressure. The model dam had detachable abutment supports and shear keys to permit variations in the 3D behavior. The results showed that the shear transfer was large between the monoliths and that the failure of a single dam monolith is unlikely. A greater lateral restraint gives not only a higher failure load but also a better indication of impending failure. These findings suggest that the entire dam, including its boundary conditions, should be considered during a stability assessment. The results also suggest that the common assumption in dam safety codes that a single monolith fails during flooding analysis is not conservative. The dataset obtained provides a foundation for the future development of dam-monitoring alarm limits and for predictive models of dam-breaching processes., QC 20231017

Dam failures may have catastrophic consequences, including the release of largeamounts of water, significant property damage, and loss of life. However, safety assessments ofconcrete gravity and buttress dams often rely on simplified methods that do not consider the interactionbetween monoliths, the shape of the foundation or the presence of stiff abutments. Numericalmodeling can be a valuable tool for analyzing the stability of these dams, but it can bedifficult to validate these models due to a lack of documented dam failures. This paper presentsthe results of a numerical study examining the ability of dynamic finite element analyses to simulatedam failures. The study used the results from a series of physical model tests as a case studyfor validation. It was found that the numerical model was able to accurately reproduce the failuremode and breach development observed in the physical model tests and capture the effect of theloading rate on the failure mode and time for the failure to develop. Simulations were also performedin prototype scale to verify that the model tests were representative of a real dam failure.Further research is needed to determine the reliability of the numerical models under differentloading conditions and in realistic geological settings. However, these findings suggest that numericalmodeling can be a valuable tool for analyzing the stability of concrete gravity and buttressdams and predicting the development of failures., QC 20231017

Fibre-reinforced shotcrete (sprayed concrete) is one of the major components in the support system for tunnels in hard rock. Several empirical design methodologies have been developed over the years due to the complexity and many uncertainties involved in rock support design. Therefore, this paper aims to highlight how the choice of design methodology and fibre type impacts the structural capacity of the lining and the emission of greenhouse gases (GHG). The paper starts with a review of different design methods. Then, an experimental campaign is presented in which the structural performance of shotcrete reinforced with various dosages of fibres made of steel, synthetic and basalt was compared. A case study is presented in which the permanent rock support is designed based on the presented design methods. Here, only the structural requirements were considered, and suitable dosages of fibres were selected based on the experimental results. The emission of GHG was calculated for all design options based on environmental product declarations for each fibre type. The result in this paper indicates that synthetic fibres have the greatest potential to lower the emissions of GHG in the design phase. Moreover, the choice of design method has a significant impact on the required dosage of fibres., QC 20230307

Drönare är ett växande fenomen i dagens samhälle och deras användningsområdenhar snabbt ökat de senaste åren. För att underlätta utvecklingen av drönarteknologi kansimuleringar tillämpas då de möjliggör testning i en kontrollerad och riskfri miljö. I dettaprojekt visualiseras simuleringar av drönare i ett försök att skapa värde för denna utveckling. Visualiseringen skedde med hjälp av Unreal Engine 5. Under projektets gång studerades arbetsmetoderna som nyttjades och hur en systemanatomi kan bidra till utvecklingen iett småskaligt mjukvaruprojekt. Största värdet som producerades för kunden var kommunikationsmodulen. Kommunikationen uppnåddes med hjälp av två JSON-filer som visualiseringen respektive simuleringen skrev till för att kommunicera med varandra. Värdeti denna modul ligger i att kunden sökte en modulär lösning för att kommunicera mellanen 3D-visualisering och en simulering. En erfarenhet som uppmärksammades angåendearbetsmetoderna är vikten av en fungerande gruppdynamik. Bidragande faktorer till detvar agila arbetsmetoder, goda kommunikationsvägar och en väl planerad användning avGit. Systemanatomier upplevdes ge begränsat värde till projektet.

Embankment dams may be damaged by internal erosion, which ultimately may lead to a failure. During internal erosion, finer soil particles from the core soil are being washed out. To restore the core function, injection grouting may be undertaken. Grouting the core of an embankment dam should be performed with a grout with similar characteristics as the original core soil. This grout type is commonly used in compaction grouting, e.g., a low mobility grout. The grout is similar to a fine-grained moraine core soil, but given its stiffness, it is difficult to permeate a damaged core soil. A modified low mobility grout containing sand, limestone filler, bentonite, plasticizer, air release agent and water has been tested in the laboratory with focus on permeation. Grouting was done in different sized aggregates. Impact of paste-to-aggregate ratio, grout consistency, maximum grain size of grout, coarseness of grouted material, and grouting methodology was tested. Higher paste-to aggregate ratios and lower viscosity/yield strength in/of the grout improved the permeation. Initially pressurized grouting compared to only hydrostatic pressures followed by stepwise pressure increased grouting was furthermore identified as a factor to improve the permeation., Validerad;2024;Nivå 2;2024-03-15 (hanlid);Funder: Svenskt Vattenkraftcentrum (SVC);Full text license: CC BY

In recent decades, many cities have become densely populated due to increased urbanization, and the transportation infrastructure system has been heavily used. The downtime of important parts of the infrastructure, such as tunnels and bridges, seriously affects the transportation system’s efficiency. For this reason, a safe and reliable infrastructure network is necessary for the economic growth and functionality of cities. At the same time, the infrastructure is ageing in many countries, and continuous inspection and maintenance are necessary. Nowadays, detailed inspections of large infrastructure are almost exclusively performed by inspectors on site, which is both time-consuming and subject to human errors. However, the recent technological advancements in computer vision, artificial intelligence (AI), and robotics have opened up the possibilities of automated inspections. Today, semiautomatic systems such as drones and other mobile mapping systems are available to collect data and reconstruct 3D digital models of infrastructure. This significantly decreases the downtime of the infrastructure, but both damage detection and assessments of the structural condition are still manually performed, with a high impact on the efficiency and accuracy of the procedure. Ongoing research has shown that deep-learning methods, especially convolutional neural networks (CNNs) combined with other image processing techniques, can automatically detect cracks on concrete surfaces and measure their metrics (e.g., length and width). However, these techniques are still under investigation. Additionally, to use these data for automatically assessing the structure, a clear link between the metrics of the cracks and the structural condition must be established. This paper presents a review of the damage of tunnel concrete lining that is detectable with optical instruments. Thereafter, state-of-the-art autonomous tunnel inspection methods are presented with a focus on innovative mobile mapp, QC 20230426, TACK -Tunnel Automatic CracK Detection

Dam safety measures on the Vattenfall hydropower facility Lilla Edet, in Sweden are, ongoing by replacing parts of the old spillway dam from the 1920s to increase discharge capacity. A climate enhanced concrete without needs for any post-cooling to avoid thermal cracking has been developed for the project. A series of tests from initial laboratory tests via development of a production mix and a full-scale mock-up preceded the construction works on site. Increase of the maximum aggregate sizes from today’s commonly used 27 mm up to 45 mm was introduced to reduce the cement content. Basic tests to verify fresh properties, air void content, strength development, shrinkage etc. was done for a series of different supplementary cementitious materials before selecting fly ash from combustion of pulverized hard coal (PFA) as cement replacement. Examination of the durability aspects like freeze-thaw and carbonation resistance by accelerated test showed no or limited impact on the properties. Development and optimization of the production mix, with use of locally available materials, was done in cooperation with the concrete supplier. The mock-up tests included two large size beams, one with reference concrete and one with the developed concept concrete. Representative reinforcement (dimensions and spacing) was installed, a full-scale concrete pump used and workers from the project executed the casting. The outcome was successful without blockage during pumping, no honeycombing and happy workers. By using installed gauges and optic fibers, early age behavior in terms of temperature and strain development was measured to be able to estimate the risk for thermal cracking. The concept concrete showed to give a substantially reduced riskfor early age thermal cracks in comparison to the reference concrete. With support from the investigations, a decision to deviate from accepted levels of cement replacement in standards was taken. This was possible since the concrete concept prove, Part of ISBN 978-91-527-8078-7QC 20231204

The Lilla Edet hydropower dam, inaugurated in 1926, is located north of Gothenburg along the river Göta älv, in Sweden. It was originally designed to supply power for the main railway line between Stockholm and Gothenburg. The need for dam safety improvements, including the capability of discharging a flood with a return period of 1:10000 years, prompted the partial reconstruction of the spillway dam. This paper describes the design decisions that have been taken regarding hydrology, hydraulic design, geological conditions, and the development of a low GHG with a reduced CO2 footprint, which does not require post-cooling., QC 20230825

Hydro power facilities in Sweden are in general exposed to large temperature variations betweensummer and winter, high moisture levels and high hydrostatic pressure on water retaining structures.In concrete structures with insufficient properties these factors co-operate and can result indegradation by e.g., frost action, erosion, leaching and stresses that can aggravate leakage of waterand further degradation or cracking of the concrete material. In concrete dams and hydro power plants different kind of joints are installed. Cold joints anddilatation joints are two common types. Dilatation joints must be designed and constructed sothey are both water retaining and flexible enough to follow thermal movements of the concretewithout rupturing. A joint that is not well constructed with a good performance can jeopardize thedam safety for a hydro power facility with uncontrolled leakage, ice-formation, degradation orproblematic erosion on the down-stream side. A laboratory study of concrete from an dilatation joint has been performed in this project. Thestudied materials are taken from a larger concrete slab of a spillway sill of a concrete dam. Thescope of the project has been to study the characteristics of the concrete around the water stop anddilatation joint. The goal was to learn more about the mechanisms behind the degradation andleaking of expansion joints., Part of ISBN 978-91-527-8078-7QC 20231208

The core of dam safety is to safely store and discharge water and thereby prevent uncontrolled release of water. Excess water, e.g. in a flooding situation, is commonly discharged via different types of spillways (gated, weirs, surface, bottom outlets etc.). The turbine discharge is typically not included in the capacity as flooding scenarios could cause a grid blackout rendering the turbine incapable of operating. This paper describes a project that has tested island operation of a hydropower unit equipped with a developed dump-load device. The dump-load device allows the unit operating even during a black-out without risk for failure of the unit and thus assure the discharge capacity via the waterways connected to the unit. Stable operation of the dump-load verified in the tests together with high reliability opens for the turbine discharge to be included inthe total discharge capacity of a facility. A cost-benefit analysis of the suggested solution and a brief description of the past and planned development of the device is given. In addition to the extra discharge capacity, the new system can also be used to reduce the risk for surge during start and stop sequences. Implementation of the system in two different facilities, with different purpose, is planned and details on the coming installations and the technical solutions around them is given. A cost comparison between conventional spillway gates and dump-load indicates a factor of ten less for dump-load for a given increase in discharge capacity. The safety analyses shows that the turbine discharge should be included in the total discharge capacity of a facility if a dump load device is present., QC 20230825

ImportanceThe Targeted Hypothermia vs Targeted Normothermia After Out-of-Hospital Cardiac Arrest (TTM2) trial reported no difference in mortality or poor functional outcome at 6 months after out-of-hospital cardiac arrest (OHCA). This predefined exploratory analysis provides more detailed estimation of brain dysfunction for the comparison of the 2 intervention regimens.ObjectivesTo investigate the effects of targeted hypothermia vs targeted normothermia on functional outcome with focus on societal participation and cognitive function in survivors 6 months after OHCA.Design, Setting, and ParticipantsThis study is a predefined analysis of an international multicenter, randomized clinical trial that took place from November 2017 to January 2020 and included participants at 61 hospitals in 14 countries. A structured follow-up for survivors performed at 6 months was by masked outcome assessors. The last follow-up took place in October 2020. Participants included 1861 adult (older than 18 years) patients with OHCA who were comatose at hospital admission. At 6 months, 939 of 1861 were alive and invited to a follow-up, of which 103 of 939 declined or were missing.InterventionsRandomization 1:1 to temperature control with targeted hypothermia at 33 °C or targeted normothermia and early treatment of fever (37.8 °C or higher).Main outcomes and measuresFunctional outcome focusing on societal participation assessed by the Glasgow Outcome Scale Extended ([GOSE] 1 to 8) and cognitive function assessed by the Montreal Cognitive Assessment ([MoCA] 0 to 30) and the Symbol Digit Modalities Test ([SDMT] z scores). Higher scores represent better outcomes.ResultsAt 6 months, 836 of 939 survivors with a mean age of 60 (SD, 13) (range, 18 to 88) years (700 of 836 male [84%]) participated in the follow-up. There were no differences between the 2 intervention groups in functional outcome focusing on societal participation (GOSE score, odds ratio, 0.91; 95% CI, 0.71-1.17; P = .46) or in cogni