A method to estimate blast-induced damage in rock considering both stress waves and gas expansion phases is presented. The method was developed by assuming a strong correlation between blast-induced damage and stress wave amplitudes, and also by adapting a 2D numerical method to estimate damage in a 3D real case. The numerical method is used to determine stress wave damage and provides an indication of zones prone to suffer greater damage by gas expansion. The specific steps carried out in this study are: i) extensive blast monitoring in hard rock at surface and underground test sites; ii) analysis of seismic waveforms in terms of amplitude and frequency and their azimuthal distribution with respect to borehole axis, iii) measurement of blast-induced damage from single-hole blasts; iv) assessment and implementation of method to utilize 2D numerical model to predict blast damage in 3D situation; v) use of experimental and numerical results to estimate relative contribution of stress waves and gas penetration to damage, and vi) monitoring and modeling of full-scale production blasts to apply developed method to estimate blast-induced damage from stress waves. The main findings in this study are: i) both P and S-waves are generated and show comparable amplitudes by blasting in boreholes; ii) amplitude and frequency of seismic waves are strongly dependent on initiation mode and direction of propagation of explosive reaction in borehole; iii) in-situ measurements indicate strongly non-symmetrical damage dependent on confinement conditions and initiation mode, and existing rock structure, and iv) gas penetration seems to be mainly responsible for damage (significant damage extension 2-4 borehole diameters from stress waves; > 22 from gas expansion). The method has the potential for application in regular production blasts for control of over-breaks and dilution in operating mines. The main areas proposed for future work are: i) verification of seismic velocity changes in rock by blast-induced damage from controlled experiments; ii) incorporation of gas expansion phase into numerical models; iii) use of 3D numerical model and verification of crack distribution prediction; iv) further studies on strain rate dependency of material strength parameters, and v) accurate measurements of in-hole pressure function considering various confinement conditions.

A method to estimate blast-induced damage in rock considering both stress waves and gas expansion phases is presented. The method was developed by assuming a strong correlation between blast-induced damage and stress wave amplitudes, and also by adapting a 2D numerical method to estimate damage in a 3D real case. The numerical method is used to determine stress wave damage and provides an indication of zones prone to suffer greater damage by gas expansion. The specific steps carried out in this study are: i) extensive blast monitoring in hard rock at surface and underground test sites; ii) analysis of seismic waveforms in terms of amplitude and frequency and their azimuthal distribution with respect to borehole axis, iii) measurement of blast-induced damage from single-hole blasts; iv) assessment and implementation of method to utilize 2D numerical model to predict blast damage in 3D situation; v) use of experimental and numerical results to estimate relative contribution of stress waves and gas penetration to damage, and vi) monitoring and modeling of full-scale production blasts to apply developed method to estimate blast-induced damage from stress waves. The main findings in this study are: i) both P and S-waves are generated and show comparable amplitudes by blasting in boreholes; ii) amplitude and frequency of seismic waves are strongly dependent on initiation mode and direction of propagation of explosive reaction in borehole; iii) in-situ measurements indicate strongly non-symmetrical damage dependent on confinement conditions and initiation mode, and existing rock structure, and iv) gas penetration seems to be mainly responsible for damage (significant damage extension 2-4 borehole diameters from stress waves; > 22 from gas expansion). The method has the potential for application in regular production blasts for control of over-breaks and dilution in operating mines. The main areas proposed for future work are: i) verification of seismic velocity changes in rock by blast-induced damage from controlled experiments; ii) incorporation of gas expansion phase into numerical models; iii) use of 3D numerical model and verification of crack distribution prediction; iv) further studies on strain rate dependency of material strength parameters, and v) accurate measurements of in-hole pressure function considering various confinement conditions.

The UK government’s Carbon Plan-2011 aims for 80% carbon emission reduction by 2050, and the 2009 UK National Renewable Energy Action Plan has set a target of delivering 15% of total energy demand by renewable energy sources by 2020. Ground Source Heat Pump (GSHP) systems can play a critical role in reaching these goals within the building sector. Achieving such benefits relies on proper design, integration, installation, commissioning, and operation of these systems. This work seeks to provide evidence to improve the practices in design, installation and operations of large GSHP systems. This evidence has been based on collection and analysis of data from an operational large-scale GSHP system providing heating and cooling to a university building. The data set is of significance in that it is collected from a large-scale system incorporating fifty-six borehole heat exchangers and four heat pumps. The data has been collected at high frequency since the start of operation and for a period of three years. The borehole heat exchanger data is intended to form a reference data set for use by other workers in model validation studies. The ground thermal properties at the site have been estimated using a novel combination of numerical model and parameter estimation methods. The utility of the reference data set has been demonstrated through application in a validation study of a numerical borehole heat exchanger model. The system heat balances and power consumption data have firstly been analysed to derive a range of performance metrics such as Seasonal Performance Factors. Analysis has been carried out at the system and individual heat pump level. Annual performance has been found satisfactory overall. A series of analyses have been carried out to investigate the roles of circulating pump energy, control system operation and dynamic behaviour. Monitoring data from one of the heat pumps has also been analysed in further detail to make comparisons with manufacturer’s steady-state performance data and with consideration to variations in fluid properties. Some modest degradation from stated performance has been identified. The most significant operational factors accounting for degradation of overall system performance have been excessive pump energy demands and short cycling behaviour. Some faults in operation of the system during the monitoring period have also been identified. A series of recommendations are made as to ways to improve the design and operation of large-scale GSHP systems based on this evidence. These recommendations are chiefly concerned with better design for part-load operation, reduction in pump energy demands and more robust control systems.

The study compared four different cooling systems and analyzed the competitiveness in those systems regarding electricity consumption, environmental impact and life cycle cost analysis. The assignment was given from the consultant company Ramböll who believed in these systems design as a solution to minimize the energy consumption in cooling systems. The purpose of the study was to facilitate the selection of cooling system by finding a key ratio for profitability in terms of energy consumption. This makes it easier to select one of these systems in project planning. A representative building model was built in the energy simulation program IDA ICE. From these result an energy profile was achieved.   The energy profile was then used in another simulation program called Polysun were detailed system regulations could be made. By programing the controllers to regulate the distribution in an efficient way the energy consumption was minimized and matches the building cooling demand. The simulation was done for one full year and the obtained total energy consumption for each system, it was then used to calculate the operational cost. The life cycle cost analysis is a tool that compare each system costs during its lifetime. A depth analysis was also done regarding the sensitivity of changes in the profitability for the systems, by applying different electrical price and cost of capital.   The study shows that the systems with different borehole storage solutions proves to be effective systems for covering the building cooling demand with a significant lower electricity consumption, compared to the system with a chiller. The different borehole storage systems also contribute to cover some parts of the heat demand, since the stored heat needs to be used in order to make the borehole storage functional. By analyzing the cooling systems in a comparative perspective, the most effective solution is identified from an economic and environmental point of view. The cooling system that only contained a borehole storage was the solution that distinguished the most regarding total electricity consumption and environmental impact. This system resulted in being the most profitable cooling system between the compared systems. The combined system with a borehole storage system and a heat pump solution was also proven to be an effective cooling system, additionally with an advantage of providing parts of the hot water demand in the building.

Utilisée depuis des milliers d’années sous ses manifestations naturelles par l’Homme, cette ressource fait l’objet d’une exploitation commerciale depuis seulement le XXe siècle, à destination du chauffage de bâtiments, de certains usages industriels ainsi que de la production d’électricité. La France compte parmi les pionniers concernant l’usage direct de la chaleur alors qu’aucune filière industrielle n’est véritablement effective pour la production d’électricité d’origine géothermique. Le projet sélectionné, intitulé FONGEOSEC, a pour objectif la conception et la réalisation d’un démonstrateur innovant préindustriel d’une centrale géothermique haute enthalpie exploité par cogénération d’électricité et de chaleur. Un travail de recherche et développement, conduit par un consortium composé de partenaires industriels et scientifiques, vise au lancement de la filière industrielle géothermique haute température en France. L’objectif général des travaux de thèse porte sur une meilleure compréhension globale des comportements hydrauliques, massiques et thermiques des formations profondes en réponse à une sollicitation anthropique de longue durée. Il s’agit d’identifier les paramètres clés régissant la réponse du complexe réservoir à la suite d’une exploitation géothermique. Un point particulier sera consacré à caractériser la part de chacun des modes de transport de chaleur en milieu poreux – conduction thermique, convection libre et forcée – dans l’établissement des performances thermiques de l’ouvrage considéré. Plusieurs dispositifs techniques d’exploitation seront proposés afin de réduire les incertitudes associées au système géothermique souterrain et garantir le succès du projet FONGEOSEC. L’impact des mécanismes thermo-convectifs au voisinage des forages d’exploitation géothermique de grande profondeur reste peu documenté, a fortiori dans le cas de dispositifs déviés adoptant une complétion particulière. L’outil retenu pour l’évaluation des performances du dispositif au contact de l’encaissant est la modélisation numérique distribuée. La variabilité des propriétés physiques de l’hydrosystème, de la conception et des modalités d’exploitation du dispositif sur le comportement hydraulique et thermique de l’exploitation est envisagée selon différentes approches développées à partir de modèles numériques 3D. / Used for thousands of years under its natural manifestations, this resource has been commercially exploited since the twentieth century, for the heating of buildings, certain industrial uses and the production of electricity. France is one of the pioneers in the direct use of heat, whereas no industrial cluster is truly effective for the production of geothermal electricity. The selected project, FONGEOSEC, aims to design and produce an innovative pre-industrial demonstrator of a high enthalpy geothermal power plant operated by cogeneration of electricity and heat. A research and development project, led by a consortium of industrial and scientific partners, aims to launch the high-temperature geothermal industrial sector in France. The general objective of this thesis is to improve the understanding of the hydraulic, mass and thermal behavior of deep porous formations in response to long-term anthropogenic stress. The aim is to identify the key parameters governing the response of the reservoir complex related to geothermal operation. A particular point will be devoted to characterize the part of each mode of transport of heat in porous medium – thermal conduction, free and forced convection – in the establishment of the thermal performances of the geothermal power plant. Several technical operating devices will be proposed to reduce the uncertainties associated with the underground geothermal system and guarantee the success of the FONGEOSEC project. The impact of thermo-convective mechanisms in the vicinity of deep geothermal borehole remains poorly documented, especially in the case of deviated wells with a complex inner geometry. The evaluation of the hydraulic and thermal performances of the device, based on 3D numerical modeling, is conducted according to different approaches.

Master’s thesis deals with the theme in three parts theoretical, practical and experimental. Project deals with heating nursery school and experiment deals with capacity reduction borehole heating exchanger for ground – source heat pump.

MESMEG / Department of Mining and Environmental Geology / Many recent studies have shown that some of the greatest water needs occur in areas underlain by crystalline rocks with complex hydrogeology. Crystalline basement rocks underlie over 60% of the South African surface, and the Limpopo Province of South Africa is no exception. Previous attempts to develop the lithologies of Limpopo for groundwater abstraction without the use of sound scientific methodologies resulted in low yielding boreholes and a higher rate of borehole failure. The complexity of the lithologies in the region necessitates the use of sound scientific methodologies for the delineation of promising groundwater potential zones. Therefore, the principal objective of the present study was to delineate groundwater potential zones through an integrated approach of remote sensing, geophysics, as well as the use of ancillary datasets. The area of focus is located in the northeastern section of Limpopo province, covering an area of about 16 800km2. Geologically, it is underlain by three Lithostratigraphic domains comprised of Archean-aged basement rocks, Soutpansberg volcano-sedimentary succession and subsidiary basins of the main Karoo young sedimentary cover. In general, the groundwater potential of a region is a function of factors such as lithology, lineaments, slope, climate and land use/ land cover. Thus, the present study used parameters such as lineaments, lithologies, slope, and land use/ land cover to produce a groundwater potential zone map. The thematic layers were prepared from raw datasets, which include; LANDSAT 8 OLI, ASTER-DEM, aeromagnetic data, geological maps, and land use/land cover data, which were overlaid in a GIS environment. The resultant groundwater map revealed the presence of five distinct classes of groundwater potential zones, which were categorised into excellent, good, moderate, low and very low. Interpretation of the results shows that the study area is dominated by areas that may be regarded as moderate water potential zones, covering about 52% of the total area. On the other hand, low and good groundwater potential zones occur in almost equal proportions of 19.52 % and 24 % respectively. The results obtained were validated using GRIP borehole dataset, and a number of follow-up geophysical surveys. iii Overlaying of the boreholes dataset on the map showed positive correlation between borehole yields groundwater potential zones. On the other hand, follow-up Vertical Electrical Sounding surveys revealed the presence of conductive layers in some selected target areas. The groundwater potential zone map and validation results provided a meaningful regional assessment of groundwater distribution in the study area. Thus, the results of this study can be used as a guideline for future groundwater exploration projects. / NRF

In the context of energy transition, geothermics play an important role for the heating and cooling supply of both residential and commercial buildings. Thereby, the increasingly and intensive utilisation of shallow geothermal resources bears the risk of over-exploitation and thus poses a future challenge to ensure the sustainability and safety of such systems. Particularly, the well-established technology of borehole heat exchanger-coupled ground source heat pumps is applied for the thermal exploitation of the shallow subsurface. Due to the complexity of the involved physical processes, numerical modelling proves to be a powerful tool to enhance process understanding as well as to aid the planning and design processes. Simulations can also support the management of thermal subsurface resources, planning and decision-making on city and regional scales. In this work, the so-called dual-continuum approach was adopted and enhanced to develop a coupled numerical model considering flow and heat transport processes in both the subsurface and borehole heat exchangers as well as the heat pumps’ performance characteristics, and including the relevant phenomena influencing the underlying processes. Beside the temperature fields, the efficiency and thus the consumption of electrical energy by the heat pump is computed, allowing for the quantification of operational costs and equivalent carbon-dioxide emissions. The model is validated and applied to a number of numerical studies. First, a comprehensive sensitivity analysis on the efficiency and sustainability of such systems is performed. Second, a method for the quantification of technically extractable shallow geothermal energy is proposed. This procedure is demonstrated by means of a case study for the city of Cologne, Germany and its implications are discussed. / Im Rahmen der Energiewende nimmt die Geothermie eine besondere Rolle in der thermische Gebäudeversorgung ein. Die zunehmende, intensive Nutzung oberflächennaher geothermischer Ressourcen erhöht die Gefahr der übermäßigen thermischen Ausbeutung des Untergrundes und stellt damit eine wachsende Herausforderung für die Nachhaltigkeit und Sicherheit solcher Systeme dar. Zur Erschließung oberflächennaher geothermischer Energie wird insbesondere die etablierte Technologie Erdwärmesonden-gekoppelter Wärmepumpen eingesetzt. Aufgrund der daran beteiligten komplexen physikalischen Prozesse erweisen sich numerische Modelle als leistungsfähiges Werkzeug zur Erweiterung des Prozessverständnisses und Unterstützung des Planungs- und Auslegungsprozesses. Zudem können Simulationen zum Management thermischer Ressourcen im Untergrund sowie zur Planung und politischen Entscheidungsfindung auf städtischen und regionalen Maßstäben beitragen. Im Rahmen dieser Arbeit wurde, basierend auf dem sogenannten ”dual-continuum approach” und unter Berücksichtigung des Einflusses der Wärmepumpe, ein erweitertes gekoppeltes numerisches Modell zur Abbildung der in Erdwärmesonden und dem Untergrund stattfindenden Strömungs- und Wärmetransportprozesse entwickelt. Das Modell ist in der Lage, alle relevanten Einflussfaktoren zu berücksichtigen. Neben den Temperaturfeldern im Untergrund und der Erdwärmesonde werden die Effizienz und damit der Stromverbrauch der Wärmepumpe simuliert. Damit können sowohl die Betriebskosten als auch der äquivalente CO 2 -Ausstoß abgeschätzt werden. Das Modell wurde validiert und in einer Reihe numerischer Studien eingesetzt. Zuerst wurde eine umfassende Sensitivitätsanalyse zur Effizienz und Nachhaltigkeit entsprechender Anlagen durchgeführt. Weiterhin wird ein Verfahren zur Quantifizierung des technisch nutzbaren, oberflächennahen geothermischen Potentials vorgestellt und anhand einer Fallstudie für die Stadt Köln demonstriert, gefolgt von einer Diskussion der Ergebnisse.

In recent years, deep geothermal energy has been widely exploited through closed-loop borehole heat exchanger system for building heating. In order to precisely evaluate the sustainable heat extraction capacity and the impact of different designs and operating parameters, two heat transfer models are implemented in the open-source scientific software OpenGeoSys (OGS), with respect to the Deep Borehole Heat Exchanger (DBHE) and Enhanced U-tube Borehole Heat Exchanger (EUBHE) system. Besides, three types of boundary conditions are implemented, including the constant inflow temperature, the constant heat extraction rate, and constant building thermal power that integrates the ground source heat pump (GSHP) module. By applying the two BHE models, the influence of different designs and operating parameters on the GSHP system is evaluated. The sustainable heat extraction capacity and efficiency of a deep EUBHE system are predicted. Moreover, its performance and efficiency are further compared against the 2-DBHE array system that has the same total borehole length. It is found that the soil thermal conductivity is the most important parameter in the design of DBHE and EUBHE systems. The sustainable specific heat extraction rate of the EUBHE system is 86.5 W/m higher than an array with 2 DBHEs. Under the building thermal load of 1.225 MW, the total electricity consumed by the EUBHE system is approximately 27 % less than the 2-DBHE array over 10 years. The average Coefficient of System Performance (CSP) value of the EUBHE system is 1.66 higher over 10 heating seasons. The two numerical models implemented in the OpenGeoSys software can be used to predict and optimize the thermal characteristics of the closed-loop DBHE and EUBHE systems in real projects.

The Colossi of Memnon are a prominent feature of the constructed landscape at ancient Thebes (modern day Luxor, Egypt). They were built on the West Bank during the later years of Amenhotep III reign and they stood in front of his royal cult temple, Mansion of Millions of Years, known today colloquially as Kôm el-Hetan. There is no consensus on the purpose of the statues and it is plausible that they were meant to represent multiple things. However, what all the theories surrounding their purpose have in common is that they are all reliant on the visibility of the statues. The Theban Harbours and Waterscapes Survey led by Angus Graham (Uppsala University) discovered that the royal cult temple and colossi statues was built on top of an elevated area of what is believed to be have been a pre-existing wadi fan (Toonen et al.2018; 2019). To the east of the temple, a minor channel of the Nile river was also discovered. The aim of this thesis was to analyse the visibility and visual experience of the Colossi of Memnon during the 18thDynasty. By analysing the boreholes from the Theban Harbours and Waterscapes Survey, I have (re)constructed the geological features of the surrounding landscape in a game engine (Unity). The visual analysis was done by a combined GIS spatial analysis and a VR based phenomenological approach. I concluded that the levees of the minor channel of the Nile were not elevated high enough to create any substantial blocking of the view from the floodplain or from inside of the channel during the low season. It was only when you got up close to the levees and kneeled on the ground that you would lose sight of parts of the colossi. As the surface level of the Nile rose during its annual cyclethe, it would be easier to observe the statues from any part of the minor channel. As for the visual experience of observing the Colossi of Memnon from different parts of the model, the experience only changed slightly from viewing the statues from the view of the floodplain or the channel. What changed the experience drastically was if you approached the statues from the front of from the side. As you approached the statues from the front you had the statues standing symmetrically in front of the temple and they are in turn facing you. Being in front of the Colossi statues creates a feeling of being part of the statues’ experience. Not only where the humans meant to see the statues, I believe that the statues were meant to see us. This as the most ideal location to observe and visually experience the statues, is where we are in the view of both the Colossi of Memnon. The experience of the statues fades as you approach them from their side where you become the observer rather than the observed. The visual experience from the side also results in that you do not get to fully take part in the experience that both statues provide. This is because one of them becomes slightly blocked by the other. / <p>På grund av pandemi utfördes opponering på distans över Zoom</p>