The primary object of the investigation reported in this paper was to obtain information that would aid in the design of a more efficient diffuser for FTU's tunnel, and thus increase the run time. Presently FTU's four inch supersonic wind tunnel uses a constant area, normal shock, diffuser to recover the fluid pressure after the test section. Also, FTU's tunnel is of the intermittent blowdown type, which provides only a relatively short test time before the storage pressure decreases to a limiting value at which flow in the test section ceases to be supersonic. The use of a constant area diffuser and normal shock pressure recovery has the disadvantage of always entailing a large loss in stagnation pressure. These losses increase as the test section Mach number increases. Since a diffuser employing a system of oblique shocks should have a better pressure recovery than one with a single normal shock, efforts were made to improve FTU's wind tunnel along these lines. Variable area diffusers whose throats can be closed after flow has been established were of interest in this report because of their higher pressure recovery. The maximum run time of FTU's wind tunnel is limited by the overall operating pressure ratio required to maintain supersonic flow in the test section area. If one can reduce the losses in the tunnel, the operating pressure ratio can be reduced. The reduction in operation pressure can result in an increase in run time. In FTU's tunnel, the majority of losses occurs in the second throat area or the supersonic diffuser. Tunnel run time improvement may be required to conduct heat transfer studies or to conduct force, moment and pressure tests. The results of the one-dimensional analyses of a variable geometry supersonic diffuser are very promising in that they show a longer run time can be obtained for FTU's tunnel. By using a variable geometry diffuser, an intermittent blowdown wind tunnel run time can be increased two to three times that of a constant are diffuser at high Mach numbers. At the design Mach number of 4.0, the theoretical run time can be increased 321 percent over the run time of a constant area diffuser. The references cited made it possible to geometrically design a relatively simple, yet efficient contractible wall (convergent-constant area-divergent) type diffuser. Three flagellates were chosen to form the side walls of the adjustable diffuser. The length of the plates were a compromise between mechanical construction requirements and the need to keep the wall convergent angle relatively small for the Mach number range of FTU's tunnel and to minimize energy losses. The first adjustable diffuser plate has an overall length of 14.5 inches. The angle of convergent for design was chosen to be 7 degrees at the design Mach number of 4.0. The second diffuser plate that forms the constant area passage has an overall length of 12 inches. The third diffuser plate that forms the divergent section has an overall length of 13.5 inches.

No description available.

The purpose of this thesis project was to design, construct and evaluate the performance of a high temperature continuous-run electric arc wind tunnel. A pilot model of such a facility was designed assuming that equilibrium air was the working gas. The pilot model facility was constructed and consisted of the following components; arc chamber, stagnation chamber, nozzle section, test and diffusor sections. In the arc chamber, the air passes through the positive column of an electric arc there-by raising its stagnation temperature before entering the stagnation chamber. Also included in the design and construction were water cooling and waste disposal systems, air supply and vacuum systems, and electric arc power supply system and control. An examination of tests performed in the electric-arc facility showed that a low density supersonic flow with a stagnation temperature of approximately 10,000 F could be produced. The power level for this flow was 36 kw; however, with an expected increase of power to 72 kw the stagnation temperature should be raised to 15,000 F. Since no valid technique for measuring temperatures of this magnitude has been perfected to the author's knowledge, these temperatures were calculated according to a method as outlined in the present thesis. The present facility will present an opportunity for study in such topic areas as (1) Aerodynamic Ablation, (2) Magnetoaerodynamic studies and (3) Qualitative studies of chemically reacting gas flows. / Master of Science

The theory used to develop curved flow as a method of obtaining dynamic stability derivatives is presented including an analysis of the flows involved in the curved flow wind tunnel and in curved flight. Equations for the forces and moments for each of these flows are presented and then used to develop equations for the corrections to the forces and moments obtained in curved flow wind tunnel tests. An example of the physical setup and of the testing procedure for curved flow testing is also presented with some of the results from a typical test. The principles involved in several other methods of testing that are also used to obtain the dynamic stability derivatives are discussed so that a comparison may be made with the curved flow method. / Master of Science

La déformation due au fluage d'un massif rocheux autour d'un tunnel a été rencontrée fréquemment. Ce phénomène est évident où il y a des tunnels creusés dans la roche tendre, des masses rocheuses faible et fortement cisaillées, ou des massifs rocheux soumis à des contraintes in-situ élevées. La déformation due au fluage se produit fréquemment au moment d’excavation des tunnels longs où il y a des failles et des zones fracturées et cisaillées. Ce phénomène peut causer différents dommages sur des systèmes de soutènement en raison de la déformation excessive et des effondrements. La déformation excessive impose une ré-excavation de la section du tunnel, qui monte le coût supplémentaire, la durée de la réalisation du projet et le risque de la sécurité sur le projet. En plus, comme la stabilité de terrain est dans un état critique durant la ré-excavation, une petite négligence peut conduire à une grande caverne. Bien que la déformation de fluage est commune dans un massif rocheux à une faible résistance dans un tunnel très profond, mais ce phénomène a été observé dans des tunnels peu profonds. Une bonne compréhension des déformations causées par une excavation souterraine requiert la connaissance de l'interaction roche-support et l'interprétation des données de terrain. Auparavant, l’objet principal de la surveillance effectuée durant la construction du tunnel était des mesures de la pression au terrain imposé sur le revêtement du tunnel. Mais aujourd’hui, les méthodes modernes de construction de tunnel se concentrent sur la surveillance des déplacements pendant et après la construction. Afin de déterminer des déformations dans les tunnels, Panet et Sulem ont supposé que "Le tunnel a une section transversale circulaire et le milieu est homogène et isotrope, aussi le tunnel est suffisamment profond pour considérer que la distribution des contraintes est homogène". Mais dans le cas quasi réel, la distribution de la contrainte autour du tunnel est hétérogène et anisotrope. Dans cette étude, pour la modification des équations Panet et Sulem, certaines équations sont proposées en cas de matériau hétérogène et anisotrope pour généraliser le problème. La galerie de force motrice Seymareh a été considérée comme l’étude de cas. Celle-ci est une partie du conduit d’eau dans le projet de centrale électrique du barrage Seymareh. Ce projet est situé à l'ouest de l'Iran. Les données de surveillance de la galerie de force motrice sont collectées au moment de l’excavation du tunnel, et sont comparées avec les résultats de la modélisation numérique et de la solution analytique. Cette comparaison montre que les résultats des données expérimentales obtenues par la surveillance sont très proches des résultats de la solution analytique, mais il y a une différence entre les deux et la modélisation numérique. Il était prévisible, car l’effet d’autres activités comme l’excavation des tunnels verticaux n’est pas prise en compte dans l’analyse numérique et aussi dans la solution analytique. Il est évident que les autres activités comme l’excavation des tunnels verticaux et l'excavation du tunnel principal vers deux directions opposées, peuvent affecter sur les résultats de la surveillance. D'autre part, les données initiales utilisées dans l'analyse numérique et la solution analytique ne sont pas tout à fait exactes, car elles sont obtenues en tant que représentatives du massif rocheux de la région, mais pas pour une section particulière. Toutefois, le but de cette étude est le développement d'une solution analytique de la déformation dans les tunnels sur les conditions générales et la poursuite de cette étude pourra être plus développée. / The creep deformation of a rock mass around a tunnel has been encountered frequently. It is particularly common in tunnels excavated in soft rock, heavily sheared weak rock masses or rock masses subjected to high in-situ stresses. Creep deformation in fault and shear fractured zones are one of the frequently encountered difficulties in long tunnel construction, which tend to cause failure of supporting systems due to excessive deformation and cavern. Excessive deformation would necessitate re-mining of the tunnel cross section, thus imposing impacts such as extra cost, extended time schedule and safety risk on the project. Furthermore, as the ground stability is in critical condition during re-mining, the slightest negligence would lead to major cavern. Although creep deformation is common to extremely poor rock mass under high overburden in a tunnel alignment, but however this phenomenon is not limited to tunnels with high overburden. A good understanding of the deformations caused by an underground excavation requires simultaneously knowledge of the rock-support interaction and interpretation of field data. Formerly, the main purpose of the monitoring carried out during tunnel construction was to measure the ground pressures acting on the tunnel lining. Modern tunneling practice emphasizes the monitoring of the displacements occurring during and after the construction. Panet and Sulem for determining of deformations in tunnels have assumed that "The tunnel has a circular cross section and around the tunnel, the rock is homogeneous and isotropic and also the tunnel is deep enough to consider that the stress distribution is homogenous". But in almost real cases, the stresses distribution around the tunnel is not homogeneous and isotropic. In this study, for modification of the Panet and Sulem equations, some equations are proposed in case of nonhomogeneous and anisotropic for generalizing of the problem. Seymareh power tunnel which is considered as a case study is a part of the powerhouse waterways system of the Seymareh dam and hydroelectric power plant project. The project is located in west of Iran. The monitoring data of power tunnel which are collected during excavation of tunnel is compared with the results of numerical modelling and analytical solution results as well as. The results obtained from comparison show although the field data, which are collected through the monitoring, are very close to the analytical solution results (approximately), but there is a significant difference between both of them and numerical modelling results. It was predictable; because the influence of the other activities such as excavation of shaft and surge tank in the numerical analysis and also analytical solution are not considered. It is obvious that other activities such as excavation of shaft and surge tank and also excavation of mean tunnel from other direction which were under operation at the same time can effect on the results of monitoring. On the other hand, the initial data which are used in numerical analysis and analytical solution are not quite accurate; because they are extracted as a representative of the rock mass of region, not for a particular section. However the goal of this study is development of analytical solution of deformation in tunnels on general conditions and pursuit of the study could be leaded to more development in this field.

Titre de l'écran-titre (visionné le 26 février 2024) / Les activités minières étant appelées à se développer à de plus en plus grande profondeur, l'intensité des réponses sismiques aux sautages de segments de galerie de développement devrait augmenter et conséquemment présenter un aléa plus important. Cette sismicité induite représente divers risques sismiques qui pourraient affecter la sécurité du personnel minier, les opérations et la rentabilité de la mine. Les réponses sismiques sont d'intensité variable et leurs facteurs d'influence ne sont pas bien compris. Habituellement, la gestion de l'aléa sismique aux réponses sismiques aux sautages de développement est liée à des règles conservatrices de type règles générales. Ces règles sont parfois ajustées selon l'expérience du personnel de la mine, non quantifiable et difficile à transmettre, ou l'historique sismique. Ces règles n'intègrent pas ou peu les connaissances de terrain. Cette thèse présente une méthodologie pour intégrer quantitativement l'influence de propriétés géologiques, structurales et mécaniques du massif rocheux dans la compréhension et l'anticipation des risques sismiques associés aux sautages de développement de galerie. La méthodologie développée est adaptable à différents contextes et peut être mise à jour par la considération de variables supplémentaires, selon les données disponibles et les conditions du site minier. Cela est possible par la quantification systématique de caractéristiques structurales, géologiques et liées au massif rocheux à chaque segment de galerie de développement. Pour démontrer l'applicabilité de la méthodologie développée, des sautages de développement de la mine LaRonde ont été étudiés. Ces sautages couvrent trois niveaux à 3 km de profondeur et pour une période s'étendant sur 17 mois. La réponse sismique au sautage de 379 segments de galerie de développement a été délimitée et quantifiée. L'acceptabilité des données collectées géologiques, structurales et liées au massif rocheux a été établie pour interpréter 32 variables pour chaque segment de galerie. Puis, des analyses statistiques bivariées et multivariées ont permis de quantifier l'influence des variables géologiques et structurales définies sur les réponses sismiques. Une approche par analyses factorielles de données mixtes (AFDM) a permis une évaluation quantitative de l'impact des variables géologiques et structurales sur les réponses sismiques, ce qui était auparavant difficile à obtenir. Cela permet de mieux évaluer le risque et planifier en conséquence. Cela peut être inestimable pour les opérations minières lors du développement minier dans une zone sismiquement active, qui demande une planification importance à court et à long terme. Les résultats d'AFDM ont montré, pour le secteur à l'étude, que quatorze variables géologiques et structurales, interprétées à chaque segment de galerie influencent significativement l'intensité des réponses sismiques au sautage de développement. Des modèles prédictifs ont été développés afin d'améliorer la compréhension et l'anticipation de la variation de l'intensité des réponses sismiques au sautage de développement. Des modèles d'analyses statistiques multivariées prédictifs d'arbre de régression d'inférence conditionnelle et de forêts aléatoires ont été développés avec 75 % des 379 segments de galeries. Les 100 segments restants ont été utilisés pour valider la performance des modèles. La stratégie d'utilisation des modèles prédictifs de forêts aléatoires proposée fournit des données quantitatives sur la variabilité des aléas sismiques associés au sautage de développement sur lesquelles les gestionnaires peuvent se baser. Les modèles prédictifs développés peuvent être utilisés pour comprendre, gérer et communiquer l'aléa sismique lié au sautage des segments de galerie de développement. Ils fournissent une évaluation quantitative de l'aléa sismique permettant aux décideurs de sélectionner des seuils de critères de performance jugés acceptables, selon leur tolérance au risque. La combinaison de l'approche proposée avec les protocoles sismiques actuels utilisés sur différents sites miniers permet d'améliorer la gestion du risque sismique associé au sautage de développement. En effet, l'utilisation du modèle prédictif pour le secteur et la période étudiés a permis d'augmenter l'exactitude, la sensibilité et la précision pour anticiper une réponse sismique d'intensité élevée à un sautage de développement. / As mining activities are expected to develop at greater depth, the intensity of seismic responses to blasting of development drift should increase and consequently present a greater hazard. This induced seismicity represents various seismic hazards that could affect the safety of mining personnel, operations, and mines' profitability. Seismic responses intensity varies and the influencing factors causing that variability are not well understood. Usually, the management of seismic hazard to seismic responses to development blasting is linked to conservative blanket rules. These rules are sometimes adjusted according to the experience of mine personnel, which is unquantifiable and difficult to communicate, or the seismic history. These rules do not consider field knowledge or at a minimum. This thesis presents a methodology to quantitatively integrate the influence of the rock mass's geological, structural, and mechanical properties in understanding and anticipating seismic risks associated with development blasting. The developed methodology is adaptable to different contexts and can be updated to consider additional variables, depending on available data and mining site conditions. This is possible by the systematic quantification of structural, geological, and rock mass-related characteristics at each segment of development drift. To demonstrate the applicability of the developed methodology, development blasts from the LaRonde mine were studied. These blasts cover three levels at a depth of 3 km and for a 17 months-period. The seismic response to the blasting of 379 segments of development drift was delineated and quantified. The collected geological, structural, and rock mass data acceptability was established to interpret 32 variables for each drift segment. Then, bivariate, and multivariate statistical analyzes made it possible to quantify the influence of the defined geological and structural variables on the seismic responses. A factor analysis of mixed data (FAMD) approach allowed a quantitative assessment of the impact of geological and structural variables on seismic responses, which was previously difficult to obtain. This allows to better assess risk and plan accordingly. This is invaluable to mining operations when mining in a seismically active area, which requires significant short- and long-term planning. For the studied sector, the FAMD results showed that 14 geological and structural variables, interpreted at each drift segment, significantly influence the intensity of seismic responses to development blasting. Predictive models have been developed to improve the understanding and anticipation of variations in the intensity of seismic responses to development blasting. Predictive multivariate statistical analysis models of conditional inference regression trees and random forests were developed with 75% of the 379 drift segments. The remaining 100 segments were used to validate the performance of the models. The proposed strategy for using predictive random forest models provides quantitative data on the variability of seismic hazards associated with development blasting that managers can rely on. The developed predictive models can be used to understand, manage, and communicate the seismic hazards associated with development blasting. They provide a quantitative seismic hazard assessment, allowing decision-makers to select acceptable performance criteria thresholds, according to their risk tolerance. Combining the proposed approach with current seismic protocols used on different mining sites makes it possible to improve seismic risk management associated with development blasting. Indeed, the use of the predictive model for the sector and period studied made it possible to increase the accuracy, sensitivity, and precision to anticipate a high-intensity seismic response to a development blast.

Various sources of error can cause discrepancies among flight test results, experimental measurements and numerical predictions in the transonic regime. For unsteady flow, the effects of wind tunnel walls or a finite computational domain are the least understood and perhaps the most important. Although various techniques can be used in steady wind tunnel testing to minimize wall reflections, e.g., using slotted walls with ventilation, wind tunnel wall effects remain in unsteady wind tunnel testing even when they have been essentially eliminated from the steady flow. Even when the walls are ten chord lengths or more from the airfoil being tested, they can have a substantial effect on the unsteady aerodynamic response of the airfoil. In this study we compare numerical computations of two- and three-dimensional unsteady transonic flow with one another, and with experimental measurements, to isolate and examine the effects of tunnel walls. An extension of the time-linearized code developed by Fung, Yu and Seebass (1978) is used to obtain numerical results in two dimensions for comparison with one another and with the experimental measurments of Davis and Malcolm (1980). The steady flow which is perturbed by small unsteady airfoil motions is found numerically by specifying the pressure distribution rather than the airfoil coordinates using the procedure provided by Fung and Chung (1982). This provides results that are nearly free from effects caused by the small perturbation approximation; it also simulates the viscous effects present in the experimental measurements. A similar algorithm, developed especially for this study, is used for the related investigations in three dimensions. Different wall conditions are simulated numerically. Aside from a shift of frequency due to nonlinear effects, our numerical predictions of resonance conditions in two dimensions agree very well with those of linear acoustic theory. A substantial discrepancy between unconfined computations and wind tunnel experiments is observed in the low frequency range. This discrepancy highlights the importance of wall interference and wind tunnel measurements of unsteady transonic flows and delineates the conditions required to suppress them satisfactorily.

Thesis (MEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Segmentally lined tunnels are increasingly being built to transfer water from one water scheme to another. The segments that line such tunnels are often in the form of pre-cast concrete sections, which are placed around the perimeter of the tunnel. As these tunnels are very expensive to construct, it is imperative that their hydraulic capacities can be calculated accurately. Even a slight variation in the design diameter has a significant effect on the cost of the tunnel. Due to the construction method involved, alternative segments are not always properly aligned. This creates roughness elements in the tunnel commonly known as steps. These steps occur randomly and vary in size. Since the steps lead to increased roughness and thus decrease the hydraulic capacity of the tunnel, it is essential that this effect be allowed for in the design of the tunnel. A hydraulic model was used to determine the contribution of steps to the hydraulic roughness, according to step size and frequency of steps. / AFRIKAANSE OPSOMMING: Tonnels word al hoe meer gebou om water tussen waterskemas te vervoer. Die voering van sulke tunnels word dikwels saamgestel uit voorafvervaardigde beton panele wat geplaas word om 'n huls langs die omtrek van die tonnel te vorm. Aangesien hierdie tonnels geweldig duur is om te bou, is dit uiters noodsaaklik dat die hidrouliese kapasiteit van 'n tonnel akkuraat bereken kan word. 'n Klein variasie in die diameter van die tonnel het 'n betekenisvolle effek op die koste daarvan. Die konstruksiemetode van sulke tonnels veroorsaak dat opeenvolgende panele nie altyd presies oplyn nie. Sulke afwykings in die belyning van die tonnelpanele veroorsaak klein trappies, wat bydra tot die ruheid in die tonne I en sodoende die kapasiteit daarvan laat afneem. Die afwykings varieer in grootte en kom in geen spesifieke patroon voor nie. 'n Modelstudie is uitgevoer om die bydrae wat die afwykings in the belyning van die opeenvolgende ringe tot die hidrouliese weerstand maak, te bepaal.

The aim of the study is to develop new analytical fragility curves for the vulnerability assessment of tunnels based on actual damage data of tunnels obtained from past earthquakes. For this purpose, additional important damage data belonging to Bolu Tunnels, Turkey was utilized as a case study. Bolu Tunnels constitute a very interesting case from the earthquake hazard point of view, since two major earthquakes, 17 August 1999 Marmara and 12 November 1999 D&uuml / zce, occurred during the construction of the tunnels. The August 17, 1999 earthquake was reported to have had minimal impact on the Bolu Tunnels. However, the November 12, 1999 earthquake caused some sections of both tunnels to collapse. The remaining sections of the tunnels survived with various damage states which were subsequently documented in detail. This valuable damage data was thoroughly utilized in this study. To develop analytical fragility curves, the methodology described by Argyroudis et al. (2007) was followed. Seismic response of the Tunnels was assessed using analytical, pseudo-static and full-dynamic approaches. In this way, it was possible to make comparisons regarding the dynamic analysis methods of tunnels to predict the seismically induced damage. Compared to the pseudo-static and full-dynamic methods, the predictive capability of the analytical method is found to be relatively low due to limitations inherent to this method. The pseudo-static and full-dynamic solution results attained appear to be closer to each other and better represented the recorded damage states in general. Still, however, the predictive capability of the pseudo-static approach was observed to be limited for particular cases with reference to the full-dynamic method, especially for the sections with increasingly difficult ground conditions. The final goal of this study is the improvement of damage indexes corresponding to the defined damage states which were proposed by Argyroudis et al. (2005) based on the previous experience of damages in tunnels and engineering judgment. These damage indexes were modified in accordance with the findings from the dynamic analyses and actual damage data documented from Bolu Tunnels following the D&uuml / zce earthquake. Three damage states were utilized to quantify the damage in this study.

A completed part of the Bolu Tunnel at Elmalik side collapsed during the 1999 D&uuml / zce earthquake. In order to by-pass the collapsed section, a new tunnel route was determined. 474 meters of the new route, including two portals and double tubing, crossed through the weak to very weak rock units with intersecting fault gouge, excavated from Elmalik side. In this study, the characteristics of the rock masses and support classes are determined for new route of the Elmalik Side. Then, during the tunnel excavation, the deformations of temporary and permanent support systems were precisely measured and recorded. The support system properties as determined from NATM were analyzed by two dimensional convergence confinement method using the numerical RocSupport software. As a result of this study, for weak ground tunneling, duration of primary support installation should be kept at minimum. Besides that, temporary support measures such as forepoling, face sealing and temporary invert have an important role in controlling deformations before the primary support installation. With the application of temporary supports, loading on the permanent support, and hence the final deformation of the excavation, was found to be reduced significantly. Application of rigid lining was found to be necessary in order to prevent long-term deformations in weak ground tunnels, even though it is contradictory to the NATM philosophy.