Water ingress into rock tunnels is a problematic phenomenon – especially in urban areas – as a lowered groundwater table may cause harmful settlements. Furthermore, too much ingress can be an incentive for the environmental court to halt the tunnel process, in order to protect the nature as part of a national interest.Water ingress is normally lowered by injecting a water and cement mixture into boreholes in the rock mass – a process called rock grouting – thus sealing the rock fractures. Very little information and research has been on the subject of how the rock fracture orientation interact with the orientation and geometry of the grouting holes. The purpose of this thesis is to investigate whether or not it is possible and feasible to select a grout fan geometry that will have the most intersections with the rock fractures, based on fracture information gained in an early pre-investigation stage. The suitability of different grout fan geometries will be determined by analyzing the amount of fracture intersections that each geometry has in a discrete fracture network, generated based on data obtained from rock cores in the Stockholm Bypass project. The assumption is that more fracture intersections means a higher chance of sealing the rock mass. The results show that there is no clear difference in number of intersections between the analyzed grout fan geometries, indicating that focus should not be on analyzing the grout fans as whole units, but rather on the scale of individual grouting holes and fractures. This thesis also highlights the importance of monitoring according to the observational method. / Vatteninläckage i bergtunnlar är ett problem, speciellt inom tätbebyggda områden, eftersom en sänkt grundvattennivå kan orsaka sättningar i jordlagren och följaktligen skada infrastruktur. Dessutom kan ett för högt vatteninläckage vara ett incitament för miljödomstolen att stoppa tunneldrivningen i ett försök att skydda den allmänna miljön i dennas roll som ett nationalintresse.Vatteninträngning i tunnlar minskas normalt genom att injicera en blandning av vatten och mikrocement i borrhål lokaliserade i bergmassan – en process som kallas för sprickinjektering – och genom detta täta bergmassan. Idag finns mycket lite information tillgänglig om hur sprickors och injekteringshålens orienteringar interagerar med varandra.Syftet med denna uppsats är att undersöka huruvida det är genomförbart att i ett tidigt förundersökningsskede bestämma en skärmgeometri som kommer ha så många sprickskärningar som möjligt. Olika skärmgeometriers lämplighet bedömdes genom att analysera mängden sprickskärningar som varje geometri hade i ett diskret spricknätverk, baserat på indata från utvalda kärnborrningar från Förbifart Stockholm. Analysen utfördes under antagandet att fler sprickskärningar ger en större chans att täta berget.Resultaten visar att det inte finns en klar skillnad i antalen skärningar olika skärmgeometrier emellan, vilket indikerar att framtida fokus inte bör läggas på att analysera skärmgeometrier som enheter, utan snarare att analysen bör utföras på individuella injekteringshål och sprickor. Denna uppsats markerar också vikten av observationer under utförandet av berguttag och sprickinjektering i enlighet med observationsmetoden.

<p>One of many applications of geohydraulic modelling is assessing the suitability of a site to host a nuclear waste repository. This modelling task is complicated by scale-dependent heterogeneity and coupled thermo-hydro-mechanical (THM) processes. The objective here was to develop methods for (i) upscaling flow and transport in fractured media from detailed-scale data and (ii) accounting for THM-induced effects on regional-scale transport. An example field data set was used for demonstration.</p><p>A systematic framework was developed where equivalent properties of flow, transport, and stress-effects were estimated with discrete fracture network (DFN) modelling, at some block scale, and then transferred to a regional-scale stochastic continuum (SC) model. The selected block scale allowed a continuum approximation of flow, but not of transport. Instead, block-scale transport was quantified by transit time distributions and modelled with a particle random walk method at the regional scale.</p><p>An enhanced SC-upscaling approach was developed to reproduce the DFN flow results more simply. This required: (i) weighting of the input well-test data by their conductivity-dependent test volumes and (ii) conductivity-dependent correlation structure. Interestingly, the best-fitting correlation structure resembled the density function of DFN transmissivities. </p><p>Channelized transport, over distances exceeding the block scale, was modelled with a transport persistence length. A linear relationship was found between this persistence length and the macroscale dispersion coefficient, with a slope equal to a representative mean block-scale dispersion coefficient.</p><p>A method was also developed to combine well-test data and rock-mechanical data in estimating fracture transmissivities, and its application was demonstrated.</p><p>Finally, an overall sequential THM analysis was introduced allowing the estimation of the significance of waste-related thermo-mechanical (TM) effects on regional transport; here TM effects are calculated separately and their impact on fracture transmissivities were incorporated into the hybrid framework. For the particular case, their effects on regional-scale transport were small.</p>

In this thesis, fractured rock masses are treated asequivalent continua for large-scale analyses of rockengineering projects. Systematic developments are made for thedetermination of equivalent mechanical and hydraulic propertiesof fractured rock masses using a hybrid discrete fracturenetwork - distinct element method (DFN-DEM) approach. Thedetermined equivalent properties are then used for a far-fieldfinite element analysis of the thermo-mechanical impacts on thestress, deformation and permeability of fractured rockssurrounding a hypothetical geological repository of nuclearwaste. The geological data were extracted from the results ofan extensive site investigation programme at Sellafield, UK,conducted by Nirex UK Ltd. The scale dependencies of the hydraulic and mechanicalproperties were investigated by using multiple realizations ofthe fracture system geometry with increasing model sizes untilproperly defined hydraulic and mechanical representativeelementary volumes (REVs) were reached. The validity of thesecond order permeability tensor and the fourth-ordermechanical compliance tensor were tested for continuum analysesat larger scales. The REV was determined to be around 5 m formechanical and hydraulic data in this study. Analysis of the stress-dependent mechanical and hydraulicproperties shows that the effect of rock stresses is crucial.The elastic moduli increase significantly with the increase ofstress and an empirical equation of stress-dependent elasticmodulus is suggested based on results of numerical experiments.Calculations of the Poisson's ratios suggest greater valuesthan are normally assumed in practice. Depending on the stateof stress, permeability decreases or increases with increasingcompressive stress. Stress-induced flow channeling effect iscaptured by numerical modeling for the first time and detailedmechanisms of shear dilation of fractures are provided. Basedon the numerical experiments, a set of empirical equations wassuggested for the stress-dependent permeability, consideringboth normal deformation and shear dilation of fractures. Thermo-mechanical impact on the performance of ahypothetical repository at a far-field scale (5 km by 1 km) wasinvestigated with the stress-dependent equivalent propertiesdetermined at the REV scale. This analysis shows thatmechanical responses vary significantly depending on how themechanical properties were determined. The change ofpermeability due to the thermal loading is, however, notsignificant in this particular case. The thesis provides a framework for systematic analysis oflarge-scale engineering applications in fractured rock masses,such as geological repositories of nuclear wastes. Keyword:Fractured rock masses, Equivalent Continuum,Discrete Fracture Network (DFN), Distinct Element Method (DEM),Finite Element Method (FEM), Nuclear Waste Disposal, CoupledThermo-Hydro-Mechanical Processes

One of many applications of geohydraulic modelling is assessing the suitability of a site to host a nuclear waste repository. This modelling task is complicated by scale-dependent heterogeneity and coupled thermo-hydro-mechanical (THM) processes. The objective here was to develop methods for (i) upscaling flow and transport in fractured media from detailed-scale data and (ii) accounting for THM-induced effects on regional-scale transport. An example field data set was used for demonstration. A systematic framework was developed where equivalent properties of flow, transport, and stress-effects were estimated with discrete fracture network (DFN) modelling, at some block scale, and then transferred to a regional-scale stochastic continuum (SC) model. The selected block scale allowed a continuum approximation of flow, but not of transport. Instead, block-scale transport was quantified by transit time distributions and modelled with a particle random walk method at the regional scale. An enhanced SC-upscaling approach was developed to reproduce the DFN flow results more simply. This required: (i) weighting of the input well-test data by their conductivity-dependent test volumes and (ii) conductivity-dependent correlation structure. Interestingly, the best-fitting correlation structure resembled the density function of DFN transmissivities. Channelized transport, over distances exceeding the block scale, was modelled with a transport persistence length. A linear relationship was found between this persistence length and the macroscale dispersion coefficient, with a slope equal to a representative mean block-scale dispersion coefficient. A method was also developed to combine well-test data and rock-mechanical data in estimating fracture transmissivities, and its application was demonstrated. Finally, an overall sequential THM analysis was introduced allowing the estimation of the significance of waste-related thermo-mechanical (TM) effects on regional transport; here TM effects are calculated separately and their impact on fracture transmissivities were incorporated into the hybrid framework. For the particular case, their effects on regional-scale transport were small.

In this thesis, the effects of size and stress on permeability, deformability and strength of fractured rock masses are investigated. A comparison study was carried out to examine the effects of considering, or not considering, the correlation between distributions of fracture apertures and fracture trace lengths on the hydro-mechanical behavior of fractured rocks. The basic concepts used are the fundamental principles of the general theory of elasticity, Representative Elementary Volume (REV), the tensor of equivalent permeability, and the strength criteria of the fractured rocks. Due to the size and stress dependence of the hydro-mechanical properties of rock fractures, the overall effective (or equivalent) hydro-mechanical properties of the fractured rocks are also size and stress-dependent. However, such dependence cannot be readily investigated in laboratory using small samples, and so numerical modeling becomes a necessary tool for estimating their impacts. In this study, a closed-form relation is established for representing the correlation between a truncated lognormal distribution of fracture apertures and a truncated power law distribution of trace lengths, as obtained from field mapping. Furthermore, a new nonlinear algorithm is developed for predicting the relationship between normal stress and normal displacement of fractures, based on the Bandis model and the correlation between aperture and length. A large number of stochastic Discrete Fracture Network (DFN) models of varying sizes were extracted from some generated large-sized parent realizations based on a realistic fracture system description from a site investigation programme at Sellafield, UK, for calculating the REV of hydro-mechanical properties of fractured rocks. Rotated DFN models were also generated and used for evaluation of the distributions of directional permeabilities, such that tensors of equivalent permeability could be established based on stochastically established REVs. The stress-dependence of the permeability and the stress-displacement behaviour were then investigated using models of REV sizes. The Discrete Element Method (DEM) was used for numerical simulation of the fluid flow, deformability properties and mechanical strength behavior of fractured rocks. The results show significant scale-dependency of rock permeability, deformability and strength, and its variation when the correlation between aperture and trace length of fractures are concerned, with the overall permeability and deformability more controlled by dominating fractures with larger apertures and higher transmissivity and deformability, compared with fracture network models having uniform aperture. As the second moment of aperture distribution increases, a fractured rock mass shows more discrete behavior and an REV is established in smaller value of second moment with much larger model size, compared with the models with uniform fracture aperture. When the fracture aperture pattern is more scattered, the overall permeability, Young’s modulus and mechanical strength change significantly. The effect of stress on permeability and fluid flow patterns in fractured rock is significant and can lead to the existence or non-existence of a permeability tensor. Stress changes the fluid flow patterns and can cause significant channeling and the permeability tensor, and REV may be destroyed or re-established at different applied stress conditions. With an increase in the confining stress on the DEM models, the strength is increased. Compared with the Hoek-Brown criterion, the Mohr-Coulomb strength envelope provides a better fit to the results of numerical biaxial compression tests, with significant changes of the strength characteristic parameters occurring when the second moment of the aperture distribution is increased. / QC 20100702

<p>In this thesis, fractured rock masses are treated asequivalent continua for large-scale analyses of rockengineering projects. Systematic developments are made for thedetermination of equivalent mechanical and hydraulic propertiesof fractured rock masses using a hybrid discrete fracturenetwork - distinct element method (DFN-DEM) approach. Thedetermined equivalent properties are then used for a far-fieldfinite element analysis of the thermo-mechanical impacts on thestress, deformation and permeability of fractured rockssurrounding a hypothetical geological repository of nuclearwaste. The geological data were extracted from the results ofan extensive site investigation programme at Sellafield, UK,conducted by Nirex UK Ltd.</p><p>The scale dependencies of the hydraulic and mechanicalproperties were investigated by using multiple realizations ofthe fracture system geometry with increasing model sizes untilproperly defined hydraulic and mechanical representativeelementary volumes (REVs) were reached. The validity of thesecond order permeability tensor and the fourth-ordermechanical compliance tensor were tested for continuum analysesat larger scales. The REV was determined to be around 5 m formechanical and hydraulic data in this study.</p><p>Analysis of the stress-dependent mechanical and hydraulicproperties shows that the effect of rock stresses is crucial.The elastic moduli increase significantly with the increase ofstress and an empirical equation of stress-dependent elasticmodulus is suggested based on results of numerical experiments.Calculations of the Poisson's ratios suggest greater valuesthan are normally assumed in practice. Depending on the stateof stress, permeability decreases or increases with increasingcompressive stress. Stress-induced flow channeling effect iscaptured by numerical modeling for the first time and detailedmechanisms of shear dilation of fractures are provided. Basedon the numerical experiments, a set of empirical equations wassuggested for the stress-dependent permeability, consideringboth normal deformation and shear dilation of fractures.</p><p>Thermo-mechanical impact on the performance of ahypothetical repository at a far-field scale (5 km by 1 km) wasinvestigated with the stress-dependent equivalent propertiesdetermined at the REV scale. This analysis shows thatmechanical responses vary significantly depending on how themechanical properties were determined. The change ofpermeability due to the thermal loading is, however, notsignificant in this particular case.</p><p>The thesis provides a framework for systematic analysis oflarge-scale engineering applications in fractured rock masses,such as geological repositories of nuclear wastes.</p><p><b>Keyword:</b>Fractured rock masses, Equivalent Continuum,Discrete Fracture Network (DFN), Distinct Element Method (DEM),Finite Element Method (FEM), Nuclear Waste Disposal, CoupledThermo-Hydro-Mechanical Processes</p>

This thesis presents a systematic numerical modeling framework to simulate the stress-deformation and coupled stress-deformation-flow processes by performing uniaxial and biaxial compressive tests on fractured rock models with considering the effects of different loading conditions, different loading directions (anisotropy), and coupled hydro-mechanical processes for evaluating strength and deformability behavior of fractured rocks. By using code UDEC of discrete element method (DEM), a series of numerical experiments were conducted on discrete fracture network models (DFN) at an established representative elementary volume (REV), based on realistic geometrical and mechanical data of fracture systems from field mapping at Sellafield, UK. The results were used to estimate the equivalent Young’s modulus and Poisson’s ratio and to fit the Mohr-Coulomb and Hoek-Brown failure criteria, represented by equivalent material properties defining these two criteria. The results demonstrate that strength and deformation parameters of fractured rocks are dependent on confining pressures, loading directions, water pressure, and mechanical and hydraulic boundary conditions. Fractured rocks behave nonlinearly, represented by their elasto-plastic behavior with a strain hardening trend. Fluid flow analysis in fractured rocks under hydro-mechanical loading conditions show an important impact of water pressure on the strength and deformability parameters of fractured rocks, due to the effective stress phenomenon, but the values of stress and strength reduction may or may not equal to the magnitude of water pressure, due to the influence of fracture system complexity. Stochastic analysis indicates that the strength and deformation properties of fractured rocks have ranges of values instead of fixed values, hence such analyses should be considered especially in cases where there is significant scatter in the rock and fracture parameters. These scientific achievements can improve our understanding of fractured rocks’ hydro-mechanical behavior and are useful for the design of large-scale in-situ experiments with large volumes of fractured rocks, considering coupled stress-deformation-flow processes in engineering practice. / <p>QC 20141111</p>

Les méthodes stochastiques de modélisation discrète de réseaux de fractures reposent principalement sur la reproduction de la géométrie du réseau de fractures naturelles décrit par des lois de distributions statistiques. Classiquement, la géométrie de chaque objet est simulée en déterminant la position, l'orientation et la géométrie d'objets planaires représentant une fracture. Cependant, l'organisation générale du réseau est émergente d'un processus stochastique et stationnaire. Cette thèse explore une approche stochastique pseudo-génétique définissant des règles d'implantation et de propagation d'objets non planaires qui permet de contraindre l'émergence d'une organisation fractale particulière. La simulation mime le processus de fracturation naturelle en contraignant le positionnement et la géométrie de chaque fracture par la zone d'accumulation des contraintes et la zone d'ombre définie autour de chaque fracture déjà simulée. Nous étudierons l'impact de la méthode proposée sur la dimension fractale du réseau de fractures discret. De même, nous mènerons une étude quantifiant l'impact de notre méthode de simulation sur la connectivité des modèles et leur seuil de percolation. La validation des approches stochastiques se base sur le réalisme de la géométrie et du comportement des modèles produits. L'approche précédemment décrite contraint les géométries locale et globale des réseaux de fractures discrets par des lois statistiques et des concepts issus de la mécanique de la fracturation. L'imagerie des discontinuités mécaniques peut aussi passer par l'interprétation de données indirectes évaluant le comportement physique et/ou dynamique du volume de roche fracturé. Nous proposons une approche efficace pour intégrer à la simulation stochastique des considérations relatives à des tests de traceurs et à la microsismicité. Nous intégrerons ces considérations à la simulation directe des objets sans passer par une optimisation qui pourrait être couteuse en temps de calcul et corrompre l'organisation fractale du réseau de fracture discret / The stochastic simulation of discrete fracture network is based on the sampling of distribution law that describes the geometry of natural fracture networks. It generally simulates each fracture by selecting the position, the geometry and the dimensions of a planar object. The general organization of the discrete fracture network emerges from this stationary and stochastic process. This thesis explores a pseudo genetic and stochastic approach using rules that drive the seeding and the propagation of non planar objects, and allow the emergence of a fractal organization. The simulation mimics the natural fracturing process by considering the constraint accumulation zone and the shadow zone associated to each fracture already simulated in the fracture seeding, growth and linkage. We explore the impact of the method on the fractal dimension of discrete fracture network models, and we quantify its impact on both the connectivity and the percolation threshold. The validation of the stochastic approach is based on the realism of models both in terms of geometry and impact on its physical behavior. Our approach constrains the geometry of discrete fracture networks at fracture and at fracture network scales using statistic distribution laws and mechanical concepts. Mechanical discontinuities can also be described by indirect data that quantify the response of the fractured rock volume to dynamic or mechanical stimulation. We propose an efficient way to take into account flow information recorded from tracer tests and microseismic events that trigger after a hydraulic stimulation. The method is integrated during the stochastic simulation in order to remove the need of an optimization process that may be time consuming or may impact the fractal organization of the network

[pt] Esta dissertação teve por objetivo expor os principais diferenciais entre um software comercial de projeto de fraturamento hidráulico (FH) com desenvolvimento de rede de fraturas discretas tridimensional e softwares de projeto de fraturamento convencional, apresentando uma análise dos efeitos da variação dos principais parâmetros que influenciam os resultados da simulação em cima de um caso real (Coeficiente de Filtrado Total e Espaçamento entre Planos de Fratura). Como esclarecimento do principal cenário de fraturamento não convencional foram apresentadas a descrição e principais propriedades de shale gas/oil (gás de folhelho e óleo de folhelho), expondo em seguida as teorias das geometrias ortogonais e a importância das fraturas naturais que embasam as doutrinas do DFN. Enquanto no fraturamento convencional adota-se um modelo de fratura planar com duas asas simétricas em relação ao poço, no fraturamento em shale gas/oil o modelo atualmente aceito é o de criação/ativação de uma fratura dominante e uma rede de fraturas paralelas e fraturas ortogonais à dominante. Foram apresentados as premissas da modelagem, as equações adicionais em relação ao FH convencional, os critérios adotados para a solução destas equações e os dados de entrada adicionais relativos à rede de fraturas. Para ilustrar os diferenciais de modelagem convencional e com rede de fraturas discretas foram apresentadas as equações governantes de um simulador pseudotridimensional convencional (P3D) e as equações governantes do simulador com criação de rede de fraturas estudado (MShale). Uma vez que os dados de entrada adicionais são o maior desafio para os projetistas de FH, apresentou-se um capítulo sobre os mesmos, com um exemplo de entrada de dados real comentado e um capítulo descrevendo as formas de saída de dados do simulador. Concluiu-se que o coeficiente de filtrado total tem grande impacto na geometria e condutividade da fratura dominante e rede de fraturas secundárias, influenciando também as concentrações de agente de sustentação, como também ficou provado que a interação entre fraturas responde pela variação do espaçamento assumido entre os planos de fratura. Verificou-se que não se deve usar softwares de projeto de fraturamento convencional em cenários de reservatórios não convencionais, pois os resultados são irrealistas. Apontou-se deficiências do software de projeto de fraturamento hidráulico com rede de fraturas analisado, como a falta de opção de se considerar, para cada fluido utilizado, o seu respectivo coeficiente de filtrado total. Espera-se que esta dissertação seja útil aos projetistas de fraturamento hidráulico ao lidar com reservatórios não convencionais como shale gas/oil e que estimule o interesse da academia por este tema. / [en] This dissertation aimed to present the main differences between commercial software for hydraulic fracturing with the development of a three - dimensional discrete fracture network and conventional fracture design software, presenting an analysis of the effects of the variation of the main parameters that influence the simulation results on a real case (Total Leakoff Coefficient and Spacing between Fracture Plans). As a clarification of the main unconventional fracturing scenario, the description and main properties of shale gas/oil were presented. Following the theories of the orthogonal geometries and the importance of the natural fractures that support the doctrines of the DFN. While in the conventional fracture, a planar fracture model with two symmetrical wings is used in relation to the well, in the shale gas/oil fracturing, the currently accepted model is the creation/activation of a dominant fracture and a network of parallel fractures and fractures orthogonal to the dominant. The modeling assumptions, the additional equations in relation to the conventional hydraulic fracture, the criteria adopted for the solution of these equations and the additional input data related to the fracture network were presented. To illustrate the conventional modeling differences and discrete fracture network, we have presented the governing equations of a conventional pseudo-three-dimensional simulator (P3D) and the governing equations of the simulator with the creation of a fracture network studied (MShale). Since additional input data is the biggest challenge for hydraulic fracturing designers, a chapter on them has been presented, with an example of actual commented data input and a chapter describing the simulator data output. It was concluded that the total filtration coefficient has a great impact on the geometry and conductivity of the dominant fracture and the network of secondary fractures, also influencing the concentrations of proppant, as it was also proved that the interaction between fractures corresponds to the variation of the assumed spacing between the fracture planes. It was verified that conventional fracture design software should not be used in scenarios of non-conventional reservoirs, because the results are unrealistic. It was pointed out deficiencies of the software of hydraulic fracturing with analyzed network of fractures, as the consideration of constant coefficient of filtration throughout the operation. It is hoped that this dissertation will be useful to hydraulic fracturing designers when dealing with unconventional reservoirs such as shale gas / oil and to stimulate the interest of the academy on this subject.

Drinking water contamination is a big concern in Sweden and is commonly traced back to being waste from former manufacturing industrial sites. Pollutants in the topsoil can be remediated by several techniques, such as decontamination or excavation but the toxins already enclosed in the bedrock cannot be treated the same and is harder to track possible contaminant pathways. To gain knowledge of modelling fluid flow and solute transport in the bedrock is therefore highly crucial to detect any safety risks. Not only for drinking water safety but also to understand possible reservoir storage or to store disposals from radioactive waste.  For this study, high levels of chlorinated solvents have been measured at a former industrial plant manufacturing electronic products, where the prominent chemicals are PCE and its degradation products. The soil will be remediated from the site, but the remaining question is if the contaminants can be further transported in the bedrock fractures to a drinking water source for the municipality. The lake is located approximately 4km from the site and will take too much time and computational effort to run the model. Instead, this study will focus on a small-scale model estimating a suitable distance from the source where additional boreholes can be placed. The model will have a size of 455 x 436 x 38m and the study will be divided into three main tasks; improve understanding of the fracture geometry by statistical analyses of the measured fractures in the study area, build and run a groundwater flow model representing the study area, investigate possible pathways of contaminant transport in the fracture networks and analyze the impact of geological features.  The methodology is divided into several parts. First, statistical analyses of the fractures will be done using the software FracMan version 8.0, which will act as a foundation of the DFN model. Next part includes calibration of the model and generation of fracture network based on the statistical analysis. The last part includes flow and transport simulations using the application Pflotran within FracMan version 8.1.  The results shows that large fracture zones affect the flow to a great extent and therefore also control the transport of contaminants in the bedrock. Because of uncertainties regarding size of the zones, additional boreholes should be placed upon their respective orientations close to the already existing boreholes to investigate their characteristics. It is also necessary to place additional boreholes randomly within the study model to detect other fracture zones and possible dominant fracture sets. The additional boreholes should be deeper than the existing ones to detect possible fracture networks further down in the bedrock. Contaminant pathways are hard to establish because of the deterministic zones that determines the flow. The scenario where no zones were included, two dominant pathways are visible, one on the upper part and one in the lower part of the model. The scenario where zones were included, one dominant pathway is visible, following the large fracture zone reaching from one borehole towards the outlet boundary. In conclusion, these results highlight the importance of doing more measurements to strengthen the basis for evaluation of pollutant transport to the nearby lake. Because of the risk of poisoning the drinking water, it is extremely important to be able to make a realistic model for contaminant transport. Since the results of flow simulations differs between different input transmissivities, next step should be to do hydraulic tests in the already existing boreholes to establish the local transmissivity for the fractures. After that, additional boreholes in the field, both on top of the measured zones close to the existing boreholes as well as boreholes randomly throughout the study area should be placed. / Rent dricksvatten är en angelägenhet för alla i Sverige och för att säkerhetsställa rent dricksvatten krävs förebyggande åtgärder som kan förhindra att föroreningar tar sig till dricksvattenkällor. Dessa åtgärder kan bland annat innehålla mätningar för att spåra föroreningens ursprung och transportvägar. Ursprungen kan oftast kopplas till avfall från gamla tillverkningsindustrier. Föroreningar som spåras till matjorden kan åtgärdas genom sanering eller schaktning medan föroreningar som tagit sig ner i berggrunden inte kan behandlas på samma sätt. Föroreningars transport genom sprickor är svåra att spåra och lokalisera på grund av oförutsägbara förhållanden med olika bergarter, kvalitéer, sprickstorlek etcetera. På grund av detta är det viktigt att kunna modellera flöden och transport av lösa ämnen för att förhindra hälso-och säkerhetsrisker. Modellering av spricksystem är även viktigt för att undersöka framtidens energiextraktion från geotermisk aktivitet, eller att kunna lagra avfall från radioaktiva ämnen.  Denna studie görs då det har mätts upp höga nivåer av klorerade lösningsmedel från en gammal fabrik som tillverkat elektronikprodukter, främst kemikalierna PCE och dess nedbrytningsprodukter. Mätningar har gjorts på platsen i form av tre borrningar och bergkartering. Föroreningar i jordmånen kommer att åtgärdas men den kvarstående funderingen är om de föroreningarna som redan tagit sig ner i berggrunden, kan transporteras genom spricknätverket fram till en sjö som kommunen använder som dricksvattenkälla. Sjön är lokaliserad ungefär fyra kilometer från den gamla anläggningen och på grund av den långa distansen kommer det krävas mycket lagring och beräkningskraft av den använda datorn. För att undvika detta, kommer denna studie i stället fokusera på en småskalig modell med den ungefärliga storleken 455 x 436 x 38m där syftet är att uppskatta var nya borrningar kan göras för att få fram mer information angående potentiella föroreningar och dess flyktvägar. Denna studie kommer vara uppdelad i tre huvudsakliga syften; göra statistiska analyser av data som samlats in från fält, bygga upp och köra en grundvattenmodell som representerar studieområdet, undersöka potentiella vägar för transport av föroreningar i spricksystemet samt analysera dess påverkan av geologiska egenskaper.  För denna studie har metoden delats upp i flera steg. Det första steget innehåller statistiska analyser av sprickorna i området som kommer utgöra grundinformationen för spricknätverket. Detta görs i programmet FracMan version 8.0. Nästa del innehåller kalibrering av modellen samt flödes- och transportsimuleringar genom applikationen Pflotran som är installerat i FracMan version 8.1.  Resultatet av flödes- och transportsimuleringarna visar att stora sprickzoner påverkar flödet i stor utsträckning och kontrollerar därför transporten av föroreningar. Storleken av sprickzonerna är svåra att bedöma då det inte finns någon mer information än det som mätts i borrhålet, där den minsta storleken är av borrhålets radie. På grund av detta lades zonerna in deterministiskt med en radie lika stor som modellen. Detta medför att resultaten över transporteringsvägar är högst bestämmande av zonerna där zonen som går mot utflödesgränsen agerar som en motorväg för föroreningar medan zonen som går mot en gräns utan utflöde agerar likt en sjö, vilket gör att partiklarna som hamnar i zonen stannar där och kan inte ta sig därifrån och fortsätta transporten. På grund av denna osäkerhet kring storleken för zonerna bör det placeras ytligare borrhål längs med orienteringen av sprickorna max 10 meter från de existerande borrhålen för att se om zonerna fortsätter eller blivit avkapade. Eftersom inga hydrauliska tester gjorts i borrhålen är det ett viktigt nästa steg för att bestämma rätt transmissivitet i sprickorna. Det är möjligt att det finns fler zoner inom området som kan bestämma flödesvägar, därför är det också viktigt att placera ut fler borrhål slumpmässigt inom området för att upptäcka fler zoner eller andra dominerande sprickorienteringar än de som hittills mätts. Alla nya borrhål bör även gå djupare än de som redan finns för att kunna upptäcka andra eventuella spricknätverk djupare ner i berggrunden. På grund av risken att kontaminera dricksvattnet är det otroligt viktigt att kunna göra en realistisk modell som representerar transporten av föroreningar. Fortsatt arbete bör därför prioritera hydrauliska tester för att bestämma transmissiviteten i spricknätverket, därefter utföra fler och djupare borrhål i området för att undersöka andra potentiella deformationer.