Manual fracture mapping in tunnels, caverns, mines or other underground spaces is a time intensive and sometimes dangerous process. A system that can automate this task could minimize human exposure to rockfalls, rockbursts or instabilities and facilitate the use of new methods of data visualization such as virtual environments. This research was undertaken to develop VTtrace; a semi-automatic fracture mapping algorithm based on image processing and analysis techniques. Images of a rock exposure surface are made using a "prosumer" grade digital camera. The grayscale images are preprocessed to remove color information and any noise or distortion. The smoothed images are converted into binary images. The binary images are then thinned to extract the fracture map. The fractures are then separated and stored as different images. Fracture properties such as the length, width, orientation and large-scale roughness are determined using photogrammetric techniques. Results from test images shows the VTtrace is effective in extracting rock discontinuity traces. Additional enhancements to the program are proposed to allow feature attributes from the three-dimensional surface to be determined. / Master of Science

<p dir="ltr">Terahertz Time Domain Spectroscopy (THz-TDS) is a powerful non-destructive, non-ionizing spectroscopic technique utilized for evaluating the optical properties of materials within the terahertz frequency range, spanning from 0.1 to 10 terahertz or wavelengths of 300 micron to 3000 micron. It effectively bridges the gap between microwave and infrared regions on the electromagnetic spectrum and its high resolution which avoiding scattering can quantify small changes in dielectric properties of media. It has high transmission through visibly opaque polymers and its ability to record both magnitude and phase information makes it a strong spectroscopic technique with applications in security, chemistry, electronics and telecommunication and non-destructive evaluation methods for solid mechanics.</p><p><br></p><p dir="ltr">This work introduces a polarization-dependent analytical model employing THz-TDS for computing strain in materials. The model establishes a correlation between volumetric strain and the change in time of arrival for a THz pulse, leveraging dielectrostrictive properties, variations in doping particle density, and changes in sample thickness due to Poisson’s effects. Validation of the analytical model is achieved through strain mapping of polydimethylsiloxane doped with highly dielectrostrictive strontium titanate (STO). Two experiments, including open-hole tensile and circular edge-notch specimens, demonstrate the efficacy of the model. Additionally, the study accounts for stress relaxation behavior to ensure measurement accuracy. Comparison of THz strain mapping results with finite element model (FEM) and surface strain measurements using digital image correlation (DIC) method highlights the technique's sensitivity to material features such as particle clumping and edge effects, while showcasing strong agreement with FEM and DIC results.</p><p><br></p><p dir="ltr">This analytical model is further expanded for experimentally mapping subsurface stress and strain in the adhesive layer of a single lap shear test. This in-situ non-destructive testing method pioneers the use of THz-TDS for stress estimation in the adhesive layer. Validation through strain mapping of STO doped Araldite 2011 epoxy adhesive with the analytical formulation is presented.</p><p dir="ltr">Finally, THz-TDS is applied for fracture front mapping in a double cantilever beam test with high-density polyethylene bonded with STO doped Araldite 2011. The phase-dependent model for mapping fracture fronts in the sub-surface adhesive layer involves analyzing convoluted waves due to interface resonances in a multi-layer structure using THz-TDS in transmission mode. The technique evaluates changes in dielectrostrictive properties and degree of separation to delineate fracture fronts. THz image enhancement algorithms facilitate crack front delineation. Error analysis on measured crack thickness is conducted to evaluate signal-to-noise ratio for THz-TDS. Additionally, an approach employing THz-TDS measured fracture propagation information for determining sub-surface stress maps in the adhesive layer and computing fracture toughness (G_Ic) is proposed. This work highlights the versatility and efficacy of THz-TDS in material characterization and stress/strain mapping in solid mechanics applications.</p>

Fracture mapping of bedrock and knowledge about how fractures influence rock strength and stability is of great importance in a constructional context. These factors largely dictate where one can build and not build in rock, and to what extent reinforcements and safety measurements are needed. In a city like Stockholm where infrastructure has been forced to expand due to a rapidly growing population, this type of knowledge plays a central role to ensure continued development. Fracture mapping is traditionally executed by a geologist who manually measures fracture orientations with a compass. However, this method bears obvious risks as the geologist must physically approach a possibly unstable rock face to carry out manual measurements of fractures and structures. In some cases, the geologist is not even allowed to approach the rock face for safety reasons. The aspect of time should not be neglected either since the process of manual measurements is often time consuming. This has resulted in newer and safer technological methods being developed and tested. In 2015, The Geological Survey of Sweden (SGU) acquired photogrammetrical equipment and 3D-modelling software ShapeMetriX to ease the fracture mapping process, obtain data of higher quality and increase personnel safety in the field. In this report, the photogrammetrical system is quality tested by comparing its results with manual field measurements. The control was carried out on three different rock faces in two locations; Torsgatan, a central street in Stockholm, and Kungens kurva, a construction site southwest of central Stockholm. The study shows that the results of ShapeMetriX correspond well to the manual field measurements and that the method has several advantages as well as disadvantages compared to conventional mapping methods. / Sprickkartering av berggrund och kunskap om hur bergets hållfasthet och stabilitet påverkas av sprickor är viktigt i konstruktionssammanhang. Dessa faktorer dikterar till stor del var man kan och inte kan bygga i berg samt till vilken grad förstärkningar och säkerhetsåtgärder behövs. I en stad lik Stockholm vars infrastruktur tvingas anpassa sig efter en kraftigt växande befolkning sätts dessa kunskaper i en ännu mer central roll för att kunna säkerställa stadens fortsatta utveckling. Sprickkartering utförs traditionellt av en geolog som med hjälp av en kompass manuellt mäter sprickors orientering. Detta medför dock uppenbara risker då denna fysiskt måste befinna sig nära bergskärningen för att kunna utföra mätningar av sprickor och strukturer. I vissa fall kan geologen, av säkerhetsskäl, inte alls närma sig den berörda ytan vilket omöjliggör en detaljerad kartering. Tidsaspekten av det hela bör inte heller bortses då manuella fältmätningar ofta är tidskrävande. Detta har resulterat i att nyare och säkrare teknologiska metoder för kartering och klassificering av berg både utvecklas och prövas. Sveriges geologiska undersökning (SGU) förvärvade 2015 fotogrammetrisk karteringsutrustning och 3D-modelleringsprogrammet ShapeMetriX för att effektivisera sprickkarteringsarbetet, erhålla data med högre kvalitét och öka säkerheten för personal I fält. I denna rapport utvärderas nämnda stereofotogrammetriska karteringsmetod med tillhörande analysmjukvara genom en jämförelse av dess resultat med manuella fältmätningar. Kontrollen utfördes på tre berghällar; en belägen på Torsgatan, en central gågata strax nordväst om centrala Stockholm och de andra vid Kungens kurva, en byggarbetsplats i närheten av Skärholmen i södra Stockholm. Resultat av studien visar att ShapeMetriX mätningar väl stämmer överens med manuella fältmätningar och även att metoden har en

To analyse the influence of fractures on hydraulic andmechanical behaviour of fractured rock masses, it is essentialto characterise fracture geometry at exposed rock faces. Thisthesis describes three semi-automatic methods for measuring andquantifying geometrical parameters of fractures, and aims tooffer a novel approach to the traditional mapping methods. Three techniques, i.e. geodetic total station, close-rangephotogrammetry and 3-D laser scanner, are used in this studyfor measurement of fracture geometry. The advantages of thesetechniques compared with the traditional method are: i)fracture geometry is quantified semi-automatically in threedimensions; ii) fracture measurements are obtained withoutphysically touching the rock face; iii) the accuracy offracture measurements is improved comparing with thetraditional method; iv) both quantitative and spatial analysisof fracture geometry is possible; v) it offers a way todigitally record the rock surface in three dimensions and invisual format as a database for other applications. The common approach for fracture mapping by using the noveltechniques comprises three main steps: i) capturing 3-Dco-ordinates of target points; ii) quantifying geometricalparameters of fractures from the recorded co-ordinates; iii)documenting the results of fracture mapping. The details ofcapturing 3-D co-ordinates of target points are introduced. Anew algorithm is developed for computing orientation offracture planes. A multiple approach for documenting thefracture mapping results is presented. Application of thesetechniques for measuring and quantifying the geometricalparameters of fractures, such as orientation, trace length andsurface roughness, are demonstrated. The presented methods can greatly improve the quality offracture measurements and avoid the drawbacks inherent intraditional methods. However, it can not replace the humancapacity to filter out and interpret the large amount ofgeometrical information displayed on the rock faces. Themethods may offer an assistance to engineers or geologists inobtaining as much information as possible about the geometryand orientation of rock fractures for rock engineeringapplications. <b>Keywords:</b>3-D laser scanner, close-range photogrammetry,engineering geology, fracture geometry, fracture mapping, rockengineering, rock faces, rock mechanics, three-dimension, totalstation.

<p>To analyse the influence of fractures on hydraulic andmechanical behaviour of fractured rock masses, it is essentialto characterise fracture geometry at exposed rock faces. Thisthesis describes three semi-automatic methods for measuring andquantifying geometrical parameters of fractures, and aims tooffer a novel approach to the traditional mapping methods.</p><p>Three techniques, i.e. geodetic total station, close-rangephotogrammetry and 3-D laser scanner, are used in this studyfor measurement of fracture geometry. The advantages of thesetechniques compared with the traditional method are: i)fracture geometry is quantified semi-automatically in threedimensions; ii) fracture measurements are obtained withoutphysically touching the rock face; iii) the accuracy offracture measurements is improved comparing with thetraditional method; iv) both quantitative and spatial analysisof fracture geometry is possible; v) it offers a way todigitally record the rock surface in three dimensions and invisual format as a database for other applications.</p><p>The common approach for fracture mapping by using the noveltechniques comprises three main steps: i) capturing 3-Dco-ordinates of target points; ii) quantifying geometricalparameters of fractures from the recorded co-ordinates; iii)documenting the results of fracture mapping. The details ofcapturing 3-D co-ordinates of target points are introduced. Anew algorithm is developed for computing orientation offracture planes. A multiple approach for documenting thefracture mapping results is presented. Application of thesetechniques for measuring and quantifying the geometricalparameters of fractures, such as orientation, trace length andsurface roughness, are demonstrated.</p><p>The presented methods can greatly improve the quality offracture measurements and avoid the drawbacks inherent intraditional methods. However, it can not replace the humancapacity to filter out and interpret the large amount ofgeometrical information displayed on the rock faces. Themethods may offer an assistance to engineers or geologists inobtaining as much information as possible about the geometryand orientation of rock fractures for rock engineeringapplications.</p><p><b>Keywords:</b>3-D laser scanner, close-range photogrammetry,engineering geology, fracture geometry, fracture mapping, rockengineering, rock faces, rock mechanics, three-dimension, totalstation.</p>

Detta examensarbete är en ansats mot en förenklad metod för sprickkartering i borrkärna och utvärderar huruvida en förenklad metod är tillämpbar vid projekt som anläggs under aktiv design och tid är en kritisk faktor. Det föreliggande arbetet är en studie baserad på data från Boliden Mineral AB, från undersökningar utförda i syfte att lokalisera en lämplig, lågpermeabel bergvolym för anläggandet av ett slutförvar för miljöfarligt avfall. Vattenflöde i kristallin bergmassa, liksom den i Sverige, förmodas traditionellt påverkas mest av sprickornas karaktär så som sprickdensitet, sprickvidd, råhet, sprickfyllning etc. Vidare påverkar sprickegenskaperna bergmassans hållfasthet, varför karaktärisering av bergmassan utgör en central roll vid byggande i berg. Effektivisering av sprickkartering under aktiv design undersöktes genom att utvärdera hur väl de parametrar som används vid karaktärisering verkar för identifiering av vattenförande strukturer. Vidare utvärderades möjligheten att minska antalet sprickor att kartera och karaktärisera vid den fysiska kärnan. Resultat i denna studie visar inte några tydliga kopplingar mellan mätsektionernas hydrauliska konduktivitet (K) och de individuella karterade parametrarna. Osäkerheterna är dock stora då mätsektionerna för de hydrauliska testerna utgörs av 10 m för uppskattande av K, som dessutom påverkas av storskaliga företeelser (t.ex. grad av sammankoppling) som vidare inte är möjligt att uppskatta från borrhålsdata. Fjärrkartering av borrhålsfilm underestimerar överlag bergkvaliteten för de tre borrhål som analyserades. En förenklad metod med ett representativt urval sprickor för fysisk kartering beskriver fördelningen av parametervärden väl, vid jämförelse mot en fullständig fysisk kartering för två borrkärnor. Lerfyllda sprickor och höga Ja-värden överestimeras dock vid den förenklade karteringen vilket potentiellt kan leda till en mer konservativ förstärkningsåtgärd än nödvändigt. Fler studier behöver dock genomföras för att utvärdera huruvida den förenklade metoden kan reflektera parametervärdenas fördelning för individuella sprickgrupper. Vidare krävs ytterligare undersökningar för utvärdering av hur robusta de presenterade metoderna är vid kartering av borrkärnor med högre sprickighet än de som använts för analys i denna studie. / This master thesis is the inception of a simplified method for logging fractures in drill holes and comprises an evaluation on whether a simplified method is applicable for projects where the observational method is used and time is a critical factor. The following work is a study based on data from Boliden Mineral AB, acquired from investigations for locating a suitable, low-permeable rock mass for a repository for hazardous waste. Water flow in crystalline bedrock, such as that found in Sweden, is traditionally thought to be most influenced by fracture characteristics like fracture density, aperture, roughness, fillings etc. Moreover, these same characteristics influence the rock mass strength, which is why the characterization of fractures is fundamental for construction in rock. To improve efficiency of fracture logging in projects maintained under the observational method, an evaluation on how well the quantified fracture characteristics work for identification of large-scale water bearing structures was performed. Furthermore, the possibility of decreasing the number of fractures to log and characterize in the core was investigated.  The results show no apparent correlations between hydraulic conductivity (K) in test sections and the individually mapped parameters. However, the uncertainties are significant, mainly because of the large sections in which the hydraulic tests were conducted, but also because of largescale features influencing K (e.g. interconnectivity) which are not possible to estimate from core data.  Remote logging of borehole images generally underestimates the quality of the rock mass for the three analyzed boreholes. A simplified method with a representative selection of fractures for physical core logging was found to describe the distribution of parameter values well, when compared to a complete physical core log for two drill cores. Clayfillings and high Ja -values are however overestimated when the simplified method is applied which may lead to a more conservative reinforcement measure than necessary. However, more studies need to be carried out to evaluate whether the simplified method can reflect the distribution of parameter values for individual fracture sets. Moreover, additional studies are required to evaluate the robustness of the suggested simplified methods in drill cores from areas of more heavily fractured bedrock than those analyzed in this study.