Print Email Facebook Twitter Micro-scale effects of stylolite orientation on the motion of tensile failure Title Micro-scale effects of stylolite orientation on the motion of tensile failure: A study analyzing strain fields of stylolite limestones using Particle Image Velocimetry Author Versluis, Barry (TU Delft Civil Engineering and Geosciences) Contributor Pluymakers, Anne (mentor) Barnhoorn, Auke (graduation committee) Degree granting institution Delft University of Technology Programme Applied Earth Sciences Date 2020-07-01 Abstract Many laboratory tests of samples where the rock fractures are based onmeso-scale (cm) characterization of effective ‘intact’ strength parameters neglecting the microstructure effects. Understanding fracturing processes atmicro-scale (mm) will require models with microstructure data. However,data is lacking on micro-scale.Stylolites are natural rock-rock interlocked interfaces which form by a localizeddissolution process and their interface contains minerals and materialdifferent from that in the surrounding host rock. Microstructures such asstylolites influence the tensile stress behaviour in a rock formation. We areinterested in stylolites because they can act as drains or as barriers to flow.Therefore, we introduce a study where we investigate on micro-scale failuremechanisms of limestone samples with stylolites in diverse orientations.In preceding study (Pluymakers et al., pers. comm.) a series of BrazilianDisc Tests was performed on eleven samples all including stylolites of microscalecarbonate samples from the ”Treuchtlinger Marmor” formation fromthe Molasse Basin (Munich, Germany). All experiments were filmed using aDSLR camera.In this study we aim to develop the use of the Particle Image Velocimetrymethod to analyze such type of movies. We use the developed Particle ImageVelocimetry method to analyze three of the movies of the preceding study,which contained samples where the stylolite is at different angles to thehorizontal axis of the sample, so to s3. Two samples has an angle of 90°between the stylolite and s3 and one with an angle of 40°.In this open-source software the pixel displacement is analyzed in frames(i.e. consecutive images, ’before’ and ’after’ image) and it calculates the velocitydistribution within the framepairs, but it is also used to derive, displayand export multiple parameters of the flow pattern. In this study we derivedand displayed the strain rate on the image pairs.The results show that the strain field of the two limestone samples of a 90°stylolite behaves identical in the two major stress drops (i.e. DStress) fromthe stress-displacement curve. However, the sample with a stylolite of 40° behaves differently. For the two 90° oriented stylolites random extension andcompression takes place at the first highest negative stress drop and symmetricextension takes place at the second highest negative stress drop fromthe stress-displacement curve. However, for the 40° oriented stylolites asymmetric extension takes place at the first highest negative stress drop fromthe stress-displacement curve. And random extension at the second drop.Another result of this study is that the strain rate obtained from PIVlab, thestrain rate per stress drop (MPa) (i.e. in the stress displacement-curve) inboth the two 90 ° stylolite samples and the 40 ° sample were different.To put this work in the broader context of the energy transition, we considerthe rapid development of the geothermal sector. Nowadays geothermalenergy is considered as one of many alternative sources of energy usingthe hot water in the Earth’s surface to generate electricity and power heating/cooling systems. The Dinantian carbonates in the Netherlands and the”Treuchtlinger Marmor” carbonates from Germany are of interest for UltraDeep Geothermal wells, because of their high geothermal potential. To enhancethe porosity/permeability in a formation where hot water needs to beextracted hydraulic fracturing can be an option and this study gives insightabout how the rock formations on micro-scale behave when tensile failureoccurs. Tensile is one of the most important properties to be evaluated forany textile material (i.e. rocks). Tensile failure is important because it occurswhen the stress on a component exceeds the strength of the material thus itdetermines the strength of a rock and consequently is influenced by singleplane of weakness such as stylolites. Subject Micro-Scale analysisGeothermal EnergyStylolitesLimestonespermeabilityStrain rateParticle Image Velocimetry (PIV)MATLABStrainBrazilian Disc TestTensile strengthTensile testsTensile failureDisplacementRock Fractures Behavior To reference this document use: http://resolver.tudelft.nl/uuid:3796ebec-7a17-41ce-b629-eb0416237e30 Coordinates 47.768889, 10.140278 Part of collection Student theses Document type bachelor thesis Rights © 2020 Barry Versluis Files PDF Bachelor_Thesis_TUDelft_A ... _Final.pdf 44.65 MB Close viewer /islandora/object/uuid:3796ebec-7a17-41ce-b629-eb0416237e30/datastream/OBJ/view