Grouting has long been implemented as a ground improvement technique to reduce the seepage through the rock mass. Grout curtains are usually constructed under dams as a barrier to prevent leakage from the reservoir. So far, the grout curtains under dams have mainly been designed by using an empirical design approach. However, the empirical approach has its limitations. Generally, the usage of “rules of thumbs” makes the design highly dependent on the experience of the designers. Lack of experience can result in insufficient or over-conservative grout curtains. For example, the stop criteria for the grouting process adopted by the empirical approach can lead to long grouting time and thus becomes inefficient. In addition, high grouting pressure may cause unexpected deformations of the rock and open up new leakage paths. To deal with these limitations, a theory-based design methodology has been developed. Theories on rock grouting developed in recent decades are used to build up the design methodology. In the theory-based design methodology, the grout curtain is treated as a structural component in the dam foundation. The geometry and location of the grout curtain is first designed with respect to three requirements: (i) the hydraulic conductivity reduction, (ii) prevention of erosion of fracture infillings and (iii) optimization of uplift reduction. Grouting work is then designed to obtain the designed geometry of the grout curtain. In the design of the grouting work, analytical calculations are implemented to determine the grouting pressure, grouting time and grout hole layout. The stop criteria are based on the grouting time, which is believed to obtain better efficiency. The principles of the observational method are implemented to deal with the uncertainties involved in the grouting process.  One of the main limitations with the proposed methodology is the limited research on the erosion process of fracture infilling materials in flowing water. To study this issue, coupled numerical analyses are performed to better understand the initiation of erosion of fracture infillings. The results show that the Hjulström and Shields diagram are not appropriate to be used to estimate the incipient motion of fracture infilling materials. Instead, a previous equation derived under laminar flows shows better agreement with the results. / Injektering har länge använts som en metod för att förstärka grunden och reducera vattenflödet i en bergmassa. Injekteringsridåer uppförs ofta under dammar som en barriär med syfte att förhindra läckage av magasinets vatten. Hittills har injekteringsridåerna i huvudsak dimensionerats baserat på empiriska metoder. De empiriska metoderna har emellertid sina begränsningar. Användandet av olika tumregler resulterar i att dimensioneringen i hög utsträckning är beroende av ingenjörens erfarenhet. Brist på erfarenhet kan resultera i en ineffektiv, eller en för konservativ, utformning av injekteringsridåerna. Till exempel kan de stoppkriterier som tillämpas i det empiriska tillvägagångssättet leda till en för lång injekteringstid och därmed bli ineffektiv. Utöver detta kan höga injekteringstryck leda till oväntade deformationer i bergmassan och nya läckagevägar.  För att hantera dessa typer av begränsningar har en teoribaserad dimensioneringsmetodik utvecklats. Teorier för berginjektering som utvecklats under de senaste decennierna används för att bygga upp metodiken. I metodiken utformas injekteringsridån som en strukturell komponent i berggrunden under dammen. Den geometriska utformningen och läget för injekteringsridån bestäms med hänsyn till tre kriterier: (i) erforderlig reduktion av den hydrauliska konduktiviteten, (ii) förhindrande av erosion av sprickfyllnadsmaterial, och (iii) optimering av reduktionen i upptryck under dammen. Injekteringsarbetet utformas därefter i syfte att eftersträva den erforderliga utformningen. I utformningen av injekteringsarbetet används analytiska beräkningar för att bestämma injekteringstryck, injekteringstid och hålavstånd. Stoppkriterier baseras på erforderlig injekteringstid, vilket bedöms uppnå en mer effektiv injektering. Principerna för observationsmetoden används för att hantera de osäkerheter som kvarstår. En av de huvudsakliga begränsningarna med den föreslagna metodiken är den begränsade kunskapen som idag finns om erosion av sprickfyllnadsmaterial vid flödande vatten. För att studera denna fråga genomfördes kopplade numeriska analyser för att bättre förstå processen kring initiering av erosion av sprickfyllnadsmaterial. Resultaten visar att Hjulströms och Shields diagram inte är lämpliga att använda. Istället visar en tidigare framtagen ekvation för laminära förhållanden en bättre överensstämmelse. / <p>QC 210512</p>

No description available.

Introduction Inflammatory bowel disease (IBD) and its complications have been well-established. The literature shows an association between IBD and decreased bone mineral density in the adult population. However, most studies have reported an association between IBD and osteoporosis, while the risk of fractures has not been well-studied. The aim of this meta-analysis is to summarize the best available evidence regarding IBS and osteoporotic fractures. Methods A review of the literature using the MEDLINE and EMBASE databases was performed during November 2017. We included cross-sectional and cohort studies that reported the relative risks, odds ratios, and hazard ratios comparing the risk of developing osteoporotic fractures among patients with IBD patients, both ulcerative colitis (UC) and Crohn's disease (CD), versus patients without IBD as controls. The pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using the generic inverse-variance method. Results After a review of the literature, seven studies fulfilled the eligibility criteria established during the analysis. A significant association was found between IBD and osteoporosis, with a pooled OR of 1.32 (95% CI, 1.2 - 1.4). Low heterogeneity among the studies was found, I=42.3. No publication bias was found using the Egger regression test p=0.18. Sensitivity analysis showed that the inclusion of data on children by Kappelman et al. (2007) did not change the results. Conclusion A significant association between IBD and the risk of developing osteoporotic fractures was observed in this study. There is a 32% increased risk, which is consistent with different cohort studies previously done.

No description available.

Fractures and fracture networks govern the mechanical and fluid flow behavior of rock masses. Tunneling and other rock mechanics applications therefore require the characterization of rock fractures based on geological data. Field investigations produce only a limited amount of data from boreholes, outcrops, cut slopes, and geophysical surveys. In tunneling, the process of excavation creates a priceless opportunity to gather more data during construction. Typically, however, these data are not utilized due to the impedance of sampling and analysis on the flow of construction, and safety concerns with sampling within unlined tunnel sections. However, the use of this additional data would increase the overall safety, quality, and cost savings of tunneling. This study deals with several aspects of the above, with the goal of creating methods and tools to allow engineers and geologists to gather and analysis fracture data in tunnels without interrupting the excavation and without compromising safety. Distribution-independent trace density and mean trace length estimators are developed using principles of stereology. An optimization technique is developed utilizing Differential Evolution to infer fracture size and shape from trace data obtained on two or more nonparallel sampling planes. A method of producing nearly bias free empirical trace length CDF's is also introduced. These new methods and tools were validated using Monte Carlo simulations. A field study was conducted in an existing tunnel allowing the above methods and tools to be further validated and tested. A relational database was developed to aid in storage, retrieval, and analysis of field data. Fracture models were built and updated using fracture data from within the tunnel. Utilization of state of the art imaging techniques allowed for remote sampling and analysis, which were enhanced by the use of 3d visualization techniques. / Ph. D.

<p>Pod pojmom politraume se podrazumeva te&scaron;ka istovremena povreda najmanje dve regije tela sa anatomskom težinom povrede AIS koja je jednaka ili veća od tri kao i ukupna izračunata anatomska težina povreda izražena ISS zbirom mora da bude veća od 15. Cilj istraživanja je da se primenom upitnika (SF36, PTSD&ndash;testa i Glazgov skale ishoda) proceni kvalitet života između politraumatizovanih pacijenata sa prelomomima dugih kostiju i politraumatizovanih bez preloma duge kosti kao i da se uoče rani pokazatelji lo&scaron;e prognoze kvaliteta života nakon zavr&scaron;etka lečenja. Istraživanje je prospektivnog karaktera i obuhvatilo je 202 politraumatizovana pacijenta koji su bili povređeni u periodu 2010-2014 godine i bili lečeni u Urgentnom Centu Kliničkog Centra Vojvodine. Od 202 politraumatizovana pacijenta na kontrolne preglede se odazvalo ukupno 72 pacijenta, 37 sa prelomima dugih kostiju - ispitivana grupa i 35 politraumatizovanih pacijenata bez preloma duge kosti koji su činili kontrolnu gupu. Godinu dana nakon zavr&scaron;etka hospitalizacije svaki ispitanik je popunjavao upitnik( SF36, PTSD test i Glazgov skala ishoda ), načinjen je klinički pregled i standardna radiografija predela preloma duge kosti. Rezultati ukazuju da ukupni kvalitet života nakon zavr&scaron;etka lečenja se ne razlikuje značajno između ispitivanih grupa, iako politraumatizovani sa prelomima dugih kostiju imaju niži kvalitet života, odnosno značajno lo&scaron;ije fizički funkcioni&scaron;u i imaju značajno če&scaron;će psihičke poremećaje (postraumatski stresni poremećaj, depresija) u odnosu na kontrolnu grupu. Tip preloma duge kosti nije uticao na krajnji kvalitet života politraumatizovanih, dok su oni sa dva i vi&scaron;e preloma imali značajno lo&scaron;iji kvalitet života. Na osnovu dobijenih rezultata konstatovali smo da veću &scaron;ansu za bolji kvalitet života imaju pacijenti mlađi od 44 godine, ukoliko su inicjalno imali vrednost ISS skora manji od 30,5 bodova, vrednosti sistolnog i dijastolnog arterijskog pritiska u referentnim vrednostima, kao i broja eritrocita i trombocita, i ukoliko su primili manje od 4 jedinica transfuzije krvi u prva 24 časa.</p> / <p>The term of polytrauma means, a patient with multiple severe injuries in at least two regions of the body with anatomical severity of trauma AIS equal or greater than three and the total calculated weight anatomical injuries expressed by ISS score must be greater than 15. The aim of our study is early estimate of quality of life in polytrauma patients with multiple fractures of the long bones and polytrauma patients without fractures of long bones as well as to detect early indicators of poor prognosis of quality of life after treatment, using questionnaires (SF 36, PTSD test and Glasgow Outcome Scale). This was prospective study and included 202 polytrauma patients who were injured during the period 2010-2014 and were treated in the Emergency Center of Clinical Center of Vojvodina. From 202 polytrauma patients, on control examinations responded 72 patients, 37 with fractures of long bones - study group and 35 polytrauma patients without fractures of long bones and they were control group. One year after the end of hospitalization each patient filled out a questionnaire (SF36, PTSD test and Glasgow Outcome Scale), made a clinical examination and standard X-rays of long bone fractures. Our results indicate that the overall quality of life after treatment is not significantly different between the groups, although polytraumatized patients with fractures have a lower quality of life and significantly worse physical functioning and have significantly more mental disorders (post-traumatic stress disorder, depression) compared to the control group. Type of long bone fractures did not affect on the final quality of life, while those patients with two or more fractures had a significantly poorer quality of life. Based on these results we concluded that greater chance for a better quality of life have patients younger than 44 years, unless they had initially ISS score less than 30.5 points, systolic and diastolic blood pressure in the reference values as well as the number of red blood cells and platelets, and if they received less than 4 units of blood transfusions in the first 24 hours.</p>

Η παρούσα διατριβή αποσκοπεί στη διερεύνηση της βέλτιστης μεθόδου θεραπείας για τα ασταθή κατάγματα κάτω πέρατος κερκίδας. Προς τούτο, μετά από μια σύντομη εισαγωγή, στο γενικό της μέρος η διατριβή παρουσιάζει στοιχεία ανατομικής και κινηματικής της πηχεοκαρπικής και της κάτω κερκιδοωλενικής. Στη συνέχεια γίνεται αναφορά στα κατάγματα του κάτω πέρατος της κερκίδος, τα προβλήματα που προκύπτουν κατά τη θεραπεία τους και το ρόλο των κυκλοτερών συστημάτων εξωτερικής οστεοσύνθεσης (Ilizarov). Στο ειδικό μέρος της διατριβής παρουσιάζεται η κλινική μελέτη που έγινε στην Ορθοπαιδική Κλινική του Πανεπιστημίου Πατρών και αφορούσε σε ασθενείς με κατάγματα κάτω πέρατος κερκίδος που αντιμετωπίστηκαν με κυκλοτερές σύστημα εξωτερικής οστεοσύνθεσης. / Unstable distal radius fractures remain a challenge for the treating orthopaedic surgeon. We present a retrospective follow-up study (mean follow-up 12.5 months) of 20 patients with 21 unstable distal radius fractures that were reduced in a closed manner and stabilized with a nonbridging Ilizarov external fixator. Subsequent insertion of olive wires for interfragmentary compression was performed in cases with intra-articular fractures. According to the overall evaluation proposed by Gartland and Werley scoring system 12 wrists were classified as excellent, 6 as good, 2 as fair and 1 as poor. Grade II pin-tract infection in distal fracture fragment was detected in 3 wires from a total of 78 (3.8%) and in 4 half pins out of a total of 9 (44.4%). Pronation was the most frequently impaired movement. This was restricted in 4 patients (19%) in whom a radioulnar transfixing wire was applied. Symptoms of irritation of superficial sensory branch of the radial nerve occurred in 3 patients with an olive wire applied in a closed manner in the distal fragment. Ilizarov method yields functional results comparable to that of other methods whilst it avoids wrist immobilization, open reduction and reoperation for implant removal. The method is associated with a low rate of major complication and satisfactory functional outcome.

Hydraulic fracturing is essential for producing gas and oil at an economic rate from low permeability sands. Most fracturing treatments use water and polymers with a gelling agent as a fracturing fluid. The water is held in the small pore spaces by capillary pressure and is not recovered when drawdown pressures are low. The un-recovered water leaves a water saturated zone around the fracture face that stops the flow of gas into the fracture. This is a particularly acute problem in low permeability formations where capillary pressures are high. Depletion (lower reservoir pressures) causes a limitation on the drawdown pressure that can be applied. A hydraulic fracturing process can be energized by the addition of a compressible, sometimes soluble, gas phase into the treatment fluid. When the well is produced, the energized fluid expands and gas comes out of solution. Energizing the fluid creates high gas saturation in the invaded zone, thereby facilitating gas flowback. A new compositional hydraulic fracturing model has been created (EFRAC). This is the first model to include changes in composition, temperature, and phase behavior of the fluid inside the fracture. An equation of state is used to evaluate the phase behavior of the fluid. These compositional effects are coupled with the fluid rheology, proppant transport, and mechanics of fracture growth to create a general model for fracture creation when energized fluids are used. In addition to the fracture propagation model, we have also introduced another new model for hydraulically fractured well productivity. This is the first and only model that takes into account both finite fracture conductivity and damage in the invaded zone in a simple analytical way. EFRAC was successfully used to simulate several fracture treatments in a gas field in South Texas. Based on production estimates, energized fluids may be required when drawdown pressures are smaller than the capillary forces in the formation. For this field, the minimum CO2 gas quality (volume % of gas) recommended is 30% for moderate differences between fracture and reservoir pressures (2900 psi reservoir, 5300 psi fracture). The minimum quality is reduced to 20% when the difference between pressures is larger, resulting in additional gas expansion in the invaded zone. Inlet fluid temperature, flowrate, and base viscosity did not have a large impact on fracture production. Finally, every stage of the fracturing treatment should be energized with a gas component to ensure high gas saturation in the invaded zone. A second, more general, sensitivity study was conducted. Simulations show that CO2 outperforms N2 as a fluid component because it has higher solubility in water at fracturing temperatures and pressures. In fact, all gas components with higher solubility in water will increase the fluid’s ability to reduce damage in the invaded zone. Adding methanol to the fracturing solution can increase the solubility of CO2. N2 should only be used if the gas leaks-off either during the creation of the fracture or during closure, resulting in gas going into the invaded zone. Experimental data is needed to determine if the gas phase leaks-off during the creation of the fracture. Simulations show that the bubbles in a fluid traveling across the face of a porous medium are not likely to attach to the surface of the rock, the filter cake, or penetrate far into the porous medium. In summary, this research has created the first compositional fracturing simulator, a useful tool to aid in energized fracture design. We have made several important and original conclusions about the best practices when using energized fluids in tight gas sands. The models and tools presented here may be used in the future to predict behavior of any multi-phase or multi-component fracturing fluid system. / text

Diagenetic and structural aspects of tight gas sandstones must be addressed concurrently in order to fully understand low-permeability sandstones and to better predict their reservoir quality attributes that arise from a combination of pore-scale and fracture distribution characteristics. This dissertation focuses on aspects of rock evolution that are germane to concurrent structural and diagenetic evolution, such as loading and thermal history, rock mechanical property evolution, and fracture timing. I tested the hypothesis that the cement precipitation step, governed by thermal exposure and grain surface attributes, governs how sandstone attributes evolve using observations from the Late Cretaceous Williams Fork sandstones from the Piceance Basin, Colorado. My research shows that essential information for predicting and understanding fracture patterns in sandstone can be obtained by unraveling cement precipitation (diagenetic) history. Fractures depend on the mechanical properties existing during fracture growth. I show that key rock mechanical properties (subcritical crack index, Young's modulus and Poisson's ratio), petrophysical behavior, and reservoir quality depend in a systematic way on time-temperature history and the intrinsic grain surface attributes of these sandstones. I classified the Williams Fork lithofacies petrographically and correlated those with log responses to create a model that can be used to predict reservoir quality and diagenesis directly from well logs. I determined rock mechanical characteristics by measuring the subcritical crack index (SCI), a mechanical property that influences fracture distribution characteristics, and by examining log-derived bulk mechanical properties. To quantify the influence of quartz cementation on the SCI and to determine the range of SCI values for sandstone of given framework composition at different diagenetic stages, I measured SCI on Williams Fork core samples and their outcrop equivalents. Diagenetic modeling is applied to determine the sandstone characteristics during fracturing. / text

<p>Impact craters are formed when a large meteorite or comethits the Earth. At the impact a shock wave is released causingabundant fracturing in the surrounding bedrock. This type offracturing is intense and occurs throughout a very large volume(>100 km³) of the bedrock. Fractures of this type have beenobserved in deep drilling, to 5 km depth, in thePuchezh-Katunki Impact Crater. At theses depths the ambienttemperature is high. Thus impact structures are candidates forpotential heat-exchange sources for extraction of geothermalenergy.</p><p>There is a relation between fracture intensity and electricresistivity in bedrock predominated by impact-generatedfractures. In crystalline bedrock changes in electricresistivity is mainly due to fracturing which is the mainsource of porosity in these rocks. Electric resistivity methodsare highly sensitivity to porosity. Furthermore highfracture-intensities have generally been associated with lowelectric resistivity. Electro-magnetic methods like Very LowFrequency Resistivity (VLF-R) and Magnetotellurics (MT) canindirectly measure electric resistivity to relatively largedepths in the bedrock.</p><p>This study will quantify the relationship between fractureintensity and electric resistivity which can be used as aprospecting tool for geothermal energy resources at largedepth.</p><p>To meet that end, a method for fracture mapping on outcropsin Swedish terrain and a method to calculate thethree-dimensional fracture frequency from two-dimensionalfracture data has been developed. The fracture traces measuredin two dimensions on outcrops are assumed to represent avertical surface and must be converted to a three-dimensionalmeasure of the fracture frequency per unit volume. Spacing, dipand trace length of fractures have been accounted for. Thebiases associated with the mapping method have also beenaccounted for (II).</p><p>The correlation between impact-induced fracturing andelectric resistivity in crystalline rocks in the Lockne Areashows that the extent of impact fracturing in crystalline rockscan be measured with electro-magnetic or electric techniques.In addition the electric resistivity of crystalline basementand impact generated Tandsby Breccia from the Lockne Craterwere determined (I).</p><p>The relation between fracture frequency and electricresistivity in fresh water conditions using the VLF-R method isestablished from data collected from both two drill holes andfrom numerous outcrops in the Björkö region. Apreliminary quantification of the fracture frequency has beenmade. The MT resistivity models, related to the two drillholes, show that porosity and mineral-conductivity variationsof the bedrock affect this relation more than the salinityvariations in the bore-hole fluid. Further research is neededto establish a firm relation between fracture frequency,salinity of rock fluid, conductivity and porosity in order tovalidate the MT resistivity models (III).</p><p><b>Keywords:</b>Electric resistivity, Fracture frequency,Impact generated fractures, Electro-magnetic techniques, VLF-Rmethod, MT method, Window-mapping technique, Three-dimensionalfracture calculations, heat-exchange structure, geothermalenergy.</p>