The focus of this thesis is to research and develop a uniaxial tensile testing technique and methodology to attain the post-peak softening response for ultra-high performance concrete under confining pressure. This particular multi-axial behavior is valuable in improving current material models in finite element simulations for US Army applications into hardened target structures.

TITLE: AN IMPROVED ROCK MASS BEHAVIOR NUMERICAL MODEL AND ITS APPLICATIONS TO LONGWALL COAL MINING The rock mass constitutive models should include elastic moduli, strength and stiffness of intact rock as well as those of joints and geometric properties of joints. The post-failure behavior of intact rock and joints must also be specified. A direct application of the above comments is in longwall coal mining where the coal as well as the immediate roof and floor strata may undergo controlled brittle failure and associated weakening in tension and shear based on post- failure characteristics of the rock mass. In addition to controlled failure and weakening of the rock mass ahead and over the longwall face, large scale caving and compaction of caved materials occur behind the longwall face. Itasca’s Cave-Hoek three dimensional constitutive model has the ability to model longwall mining process that involve the above mentioned mechanism of rock mass failure and compaction. However, its testing to date is limited. The overall goals of research are two-fold: 1) Develop numerical modeling approaches that consider the caving behavior of jointed rock masses in design and analysis, and 2) Apply these techniques in designing stable chain-pillars and set-up rooms for longwall coal mining. Specific objectives are to: 1) Develop an improved constitutive model for prediction of post-peak behavior of rock masses typical of longwall mining in Illinois, 2) Implement the improved model for predicting gob material behavior using FLAC3D numerical code (most commercial codes do not have a built in model for gob material) and its effects on load transfer into gate entries, 3) Identify mechanisms of instability in setup rooms, 4) Develop alternate 3- and 4-entry set-up room geometries using 3-D numerical analyses, 5) Implement and field demonstrate developed geometries, and 6) Monitor performance of implemented geometries through field monitoring. An alternative method to estimate the residual strength of a rock mass is developed. A yielded rock mass and a rock fill have several common characteristics including dilation behavior under low confinement and extensive crushing of contact points under high stress, which decrease dilation. The residual strength takes on an initial value in the immediate post-peak (corresponding to near-zero porosity) condition, then degrades to an ultimate residual strength that is lower as a result of bulking, a corresponding increase in porosity, and a drop in interlock under continued shear. The following comments summarize the key findings of this research: • The model for predicting rock fill material shear strength was used as a residual strength criterion. A relationship for estimating Hoek-Brown residual parameters as a function of equivalent roughness of rock fill particles and basic friction angle was used. • Macro-level measurements around setup rooms and gate entry development areas indicated that most of the observed ground control problems may be related to subsidence movements over the setup rooms area. • Mechanisms that may be responsible for poor ground conditions in setup rooms and adjoining gate entries were identified. Collected field data and numerical analyses results tend to support the identified mechanisms. • The integrated field monitoring and numerical modeling study here assisted the cooperating coal company to plan for additional supports in development entries impacted by the fault zone and in taking appropriate safety measures while the longwall face advanced toward the fault and crossed it.

Made available in DSpace on 2014-06-11T19:27:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-21Bitstream added on 2014-06-13T20:17:01Z : No. of bitstreams: 1 vercese_f_me_botfmvz.pdf: 499084 bytes, checksum: e9070bee19e12429c7bbf0b7cc0adb1f (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Universidade Estadual Paulista (UNESP) / Com o objetivo de avaliar o efeito da temperatura sobre o desempenho e qualidade de ovos de codornas japonesas foi realizado um experimento utilizando-se 480 aves na fase de pós-pico de produção. As aves foram alojadas em uma câmara bioclimática com controle automático de temperatura, contendo duas baterias compostas de cinco andares e dez gaiolas, com capacidade para 24 aves cada gaiola, divididas em dois grupos: 240 aves no grupo controle (21°C) e 240 aves no grupo experimental, com temperaturas contínuas de 24, 27, 30, 33 e 36°C em períodos de 14 dias. O período experimental, com duração de 105 dias, foi dividido em cinco ciclos de 21 dias (um ciclo para cada temperatura), sendo 14 dias na temperatura teste e sete dias na temperatura termoneutra. No final de cada ciclo experimental foi avaliado o desempenho e a qualidade dos ovos. Para todos os tratamentos, as rações foram isonutritivas e isocalóricas. Para a avaliação do desempenho e da qualidade dos ovos utilizou-se um delineamento inteiramente casualisado com dois tratamentos (temperatura termoneutra e temperatura teste) e dez repetições de 24 aves por parcela. A elevação da temperatura piora o consumo de ração, reduz o peso dos ovos, a produção e a massa de ovos. Em temperaturas superiores a 27°C houve piora na qualidade interna e externa dos ovos. / In order to evaluate the effect of temperature on performance and egg quality of Japanese quails was conducted an experiment using 480 birds in the post-peak production. The birds were housed in a climate chamber with automatic temperature control, with two batteries composed of five floors and ten cages for up to 24 birds in each cage, divided into two groups: 240 birds in the control group (21oC) and 240 birds in the experimental group, which temperatures of 24, 27, 30, 33 and 36°C. The experiment, lasting 105 days, was divided into five 21-day cycles (one cycle for each temperature), and 14 days at test and seven days a thermoneutral. At the end of each experimental cycle was evaluated performance and egg quality. For all treatments, the diets were isocaloric and isonutritives. For the evaluation of performance and quality of eggs used a completely randomized design with two treatments (temperature and thermoneutral temperature test) and ten replicates of 24 birds per plot. Elevated temperature worsens the feed intake, egg weight, production and egg mass. At temperatures above 27°C worsened the internal and external quality of eggs.

This dissertation evaluates the behavior of Geosynthetic-Reinforced Soil (GRS) retaining structures under various soil stress states, with specific interest in the development and distribution of soil and reinforcement stresses within these structures. The stress distribution within the GRS structures is the basis of much of the industry’s current design. Unfortunately, the stress information is often not directly accessible through most of current physical testing and full-scale monitoring methods. Numerical simulations like the finite element method have provided good predictions of conservatively designed GRS structures under working stress conditions. They have provided little insight, however, into the stress information under large soil strain conditions. This is because in most soil constitutive models the post-peak behavior of soils is not well represented. Also, appropriate numerical procedures are not generally available in finite element codes, the codes used in geotechnical applications. Such procedures are crucial to properly evaluating comparatively flexible structures like GRS structures. Consequently, this study tries to integrate newly developed numerical procedures to improve the prediction of performance of GRS structures under large soil strain conditions. There are three specific objectives: 1) to develop a new softening soil model for modeling the soil’s post-peak behavior; 2) to implement a stress integration algorithm, modified forward Euler method with error control, for obtaining better stress integration results; and 3) to implement a nonlinear reinforcement model for representing the nonlinear behavior of reinforcements under large strains. The numerical implementations were made into a finite element research code, named Nonlinear Analysis of Geotechnical Problems (ANLOG). The updated finite element model was validated against actual measurement data from centrifuge testing on GRS slopes (under both working stress and failure conditions). Examined here is the soil and reinforcement stress information. This information was obtained from validated finite element simulations under various stress conditions. An understanding of the actual developed soil and reinforcement stresses offers important insights into the basis of design (e.g., examining in current design guidelines the design methods of internal stability). Such understanding also clarifies some controversial issues in current design. This dissertation specifically addresses the following issues: 1) the evolution of stresses and strains along failure surface; 2) soil strength properties (e.g., peak or residual shear strength) that govern the stability of GRS structures; 3) the mobilization of reinforcement tensions. The numerical result describes the stress response by evaluating the development of soil stress level S. This level is defined as the ratio of the current mobilized soil shear strength to the peak soil shear strength. As loading increases, areas of high stress levels are developed and propagated along the potential failure surface. After the stress levels reach unity (i.e., soil reaches its peak strength), the beginning of softening of soil strength is observed at both the top and toe of the slope. Afterward, the zones undergoing soil softening are linked, forming a band through the entire structure (i.e., a fully developed failure surface). Once the band has formed and there are a few loading increments, the system soon reaches, depending on the tensile strength of the reinforcements, instability. The numerical results also show that the failure surface corresponds to the locus of intense soil strains and the peak reinforcement strain at each reinforcement layer. What dominates the stability of GRS structures is the soil peak strength before the completed linkage of soil-softening regions. Afterward, the stability of GRS structures is mainly sustained by the soil shear strength in the post-peak region and the tensile strength of reinforcements. It was also observed that the mobilization of reinforcement tensions is disproportional to the mobilization of soil strength. Tension in the reinforcements is barely mobilized before soil along the failure surface first reaches its peak shear strength. When the average mobilization of soil shear strength along the potential failure surface exceeds approximately 95% of its peak strength, the reinforcement tensions start to be rapidly mobilized. Even so, when the average mobilization of soil strength reaches 100% of its peak shear strength, still over 30% of average reinforcement strength has not yet been mobilized. The results were used to explain important aspects of the current design methods (i.e., earth pressure method and limit equilibrium analysis) that result in conservatively designed GRS structures. / text

Resumo: Com o objetivo de avaliar o efeito da temperatura sobre o desempenho e qualidade de ovos de codornas japonesas foi realizado um experimento utilizando-se 480 aves na fase de pós-pico de produção. As aves foram alojadas em uma câmara bioclimática com controle automático de temperatura, contendo duas baterias compostas de cinco andares e dez gaiolas, com capacidade para 24 aves cada gaiola, divididas em dois grupos: 240 aves no grupo controle (21°C) e 240 aves no grupo experimental, com temperaturas contínuas de 24, 27, 30, 33 e 36°C em períodos de 14 dias. O período experimental, com duração de 105 dias, foi dividido em cinco ciclos de 21 dias (um ciclo para cada temperatura), sendo 14 dias na temperatura teste e sete dias na temperatura termoneutra. No final de cada ciclo experimental foi avaliado o desempenho e a qualidade dos ovos. Para todos os tratamentos, as rações foram isonutritivas e isocalóricas. Para a avaliação do desempenho e da qualidade dos ovos utilizou-se um delineamento inteiramente casualisado com dois tratamentos (temperatura termoneutra e temperatura teste) e dez repetições de 24 aves por parcela. A elevação da temperatura piora o consumo de ração, reduz o peso dos ovos, a produção e a massa de ovos. Em temperaturas superiores a 27°C houve piora na qualidade interna e externa dos ovos. / Abstract: In order to evaluate the effect of temperature on performance and egg quality of Japanese quails was conducted an experiment using 480 birds in the post-peak production. The birds were housed in a climate chamber with automatic temperature control, with two batteries composed of five floors and ten cages for up to 24 birds in each cage, divided into two groups: 240 birds in the control group (21oC) and 240 birds in the experimental group, which temperatures of 24, 27, 30, 33 and 36°C. The experiment, lasting 105 days, was divided into five 21-day cycles (one cycle for each temperature), and 14 days at test and seven days a thermoneutral. At the end of each experimental cycle was evaluated performance and egg quality. For all treatments, the diets were isocaloric and isonutritives. For the evaluation of performance and quality of eggs used a completely randomized design with two treatments (temperature and thermoneutral temperature test) and ten replicates of 24 birds per plot. Elevated temperature worsens the feed intake, egg weight, production and egg mass. At temperatures above 27°C worsened the internal and external quality of eggs. / Orientador: Edivaldo Antônio Garcia / Coorientador: Jose Roberto Sartori / Banca: Raphael Lúcio Andreatti Filho / Banca: Antônio Carlos de Laurentiz / Mestre

As hard rock mining progresses into higher stress mining conditions through either late stage extraction or mining at depth, the rock mass is driven not just to the peak strength, but often well into the post-peak until complete ‘failure’ occurs and easier mining conditions become evident. Limited research has been accomplished in identifying the transition of the rock mass and its behaviour into the post-peak and this research investigates this behaviour in detail. As the rock mass progressively fails, fractures are initiated through intact rock and extension and shear failure of these and pre-existing features occurs. Associated with this failure are microseismic events, which can be used to give an indication of the strength state of the rock mass. Based on an analogy to laboratory testing of intact rock and measurement of acoustic emissions, the microseismicity can be used to identify, fracture initiation, coalescence of fractures (yield), localization (peak-strength), accumulation of damage (post-peak) and ultimate failure (residual strength) leading to aseismic behaviour. The case studies presented in this thesis provide an opportunity to examine and analyse rock mass failure into the post-peak, through the regional and confined failures at the Williams and the Golden Giant mines, both in the Hemlo camp in Northern Ontario, Canada. At the Williams mine, the progressive failure of a sill pillar region into the post-peak was analysed; relating the seismic event density, combined with numerical modelling and a spatial and temporal examination of the principal components analysis (PCA), to characterize the extent, trend and state of the yielding zone, which formed a macrofracture shear structure. Observations of conventional displacement instrumentation, indicates regional dilation or shear of the rock mass occurs at or prior to the point of ‘disassociation’ (breakdown of stable PCA trends) when approaching the residual strength. At the Golden Giant mine, the complete process from initiation to aseismic behaviour is monitored in a highly stressed and confined pendent pillar. The PCA technique, numerical modelling and focal mechanism studies are used to define significant stages of the failure process, in which a similar macrofracture structure was formed. Temporal observations of key source parameters show significant changes prior to and at the point of coalescence and localization.

Ce travail comprend des études concernant lendommagement, la rupture et leurs influences sur la perméabilité du béton. Des analyses théoriques et expérimentales ont été présentées pour mettre en évidence le mécanisme dinitiation et de propagation des fissures dans le béton, ainsi que lévolution de la perméabilité de ce matériau sous laction dune charge et de la température. Une étude bibliographique est dabord réalisée. Elle constituera une base de connaissance bien utile pour les problèmes étudiés dans ce travail. Les comportements mécaniques, les modèles constitutifs du béton, notamment les modèles dendommagement et de rupture, ont été analysés en détail. Le modèle Mazars a été choisi comme le modèle de référence pour le développement de nos recherches. Lévolution de la perméabilité du béton en fonction des charges mécaniques appliquées ou de la température est également abordée dans cette étude bibliographique. Un programme dessai a été réalisé pour déterminer les paramètres de ruptures de bétons ordinaires couramment utilisés au Vietnam. Lénergie de rupture, le facteur dintensité de contrainte et la longueur caractéristique des zones de rupture ont été définis comme des fonctions de la résistance en compression et de la taille des éprouvettes dessai. Une loi deffet déchelle est aussi établie pour les différents types bétons analysés. Lapproche non-locale dans lintégration de la loi de comportement a été introduite dans le code aux éléments finis Lagamine, afin de tenir compte de la localisation de la déformation dans les zones endommagées du béton. Des exemples de simulations ont montré lavantage du modèle dendommagement non-local. Une analyse de sensibilité des résultats numériques avec les paramètres dendommagement est réalisée et permet de déterminer ces paramètres par calage pour les bétons testés. Les jeux de paramètres ainsi obtenus ont été validés par comparaison entre les réponses numériques et expérimentales sur des poutres simples en béton armé. Un deuxième programme dessai a également été effectué dans ce travail pour étudier lévolution de la perméabilité du béton sous laction de la charge mécanique et de la température. Les valeurs de la perméabilité à leau et au gaz sont mesurées simultanément et permettent dobtenir une comparaison relative. Ces résultats expérimentaux accompagnés dautres résultats expérimentaux de la littérature ont été pris comme base pour la proposition des modèles mécaniques, thermiques et thermo-mécaniques dévolution de la perméabilité du béton. Lévolution de la perméabilité est considérée non seulement comme une fonction de lendommagement diffus, mais aussi de lendommagement localisé. Afin de calculer les valeurs de la perméabilité du béton fissuré, la loi de Poiseuille a été utilisée. Une technique est alors proposée afin de pouvoir utiliser cette loi dans une approche continue. Cette loi pourrait alors être utilisée pour déterminer la perméabilité à travers un milieu fissuré. Les lois dévolution de la perméabilité proposées ont été implémentées dans le code Lagamine. Des exemples de simulation ont été réalisés pour calculer la perméabilité structurelle à travers des structures en béton dune part sous chargement et dautre part sous chargement et température simultanément / This work concerns the study of the damage, the fracture and their effects on the permeability values of concrete. Theoretical and experimental analysis have been represented to clarify the mechanism of crack initiation and crack propagation in concrete as well as the evolution of permeability values of this material under the action of mechanical load and temperature. A literature preview was carried out first to have a good background of considered problems in this work. Mechanical behaviors, constitutive models, especially damage and fracture models have been analyzed in detail. The Mazars damage model has been chosen as the base to develop further researches. The permeability of concrete was also mentioned in this study based on the published results in literature. An experimental program has been carried out to determine fracture parameters of ordinary concretes commonly used in Vietnam. Fracture energy, stress intensity factor and characteristic length of fracture process zones were represented as functions of compressive resistance and structural dimensions. The size effect law was also established for considered concretes. Nonlocal approach of integral formula was added in finite elements code Lagamine to take into account the strain localization in damaged zones of concrete. Some examples of simulation were realized to prove the advantages of nonlocal damage model. The dependence of numerical results on damage parameters was taken as a basis to carry out a calibrating process of these parameters for considered ordinary concretes. The obtained sets of damage parameters have been validated by a comparison of numerical responses beside experimental ones of simple reinforced concrete beams. A second experimental program was also realized in this work to study the evolution of permeability of concrete under the action of mechanical loading and temperature. The values of water and gas permeability are measured in the same time to have a relative comparison of these ones. These experimental results together with experimental results in literature were taken as a basis of the proposition of some mechanical, thermo-mechanical models of fluid permeability of concrete. The evolution of permeability was considered not only as a function of diffuse damage but also localized damage. In order to calculate permeability values of cracked concrete, the Poiseuille law has been used, a technique was then proposed to be able to use this law in a continuous approach that could have a good prediction of permeability through cracked media. The proposed laws of permeability were implanted in Lagaminde code. Some examples of simulation have been carried out to calculate the structural permeability through concrete structures under mechanical action and under thermo-mechanical action

As hard rock mining progresses into higher stress mining conditions through either late stage extraction or mining at depth, the rock mass is driven not just to the peak strength, but often well into the post-peak until complete ‘failure’ occurs and easier mining conditions become evident. Limited research has been accomplished in identifying the transition of the rock mass and its behaviour into the post-peak and this research investigates this behaviour in detail. As the rock mass progressively fails, fractures are initiated through intact rock and extension and shear failure of these and pre-existing features occurs. Associated with this failure are microseismic events, which can be used to give an indication of the strength state of the rock mass. Based on an analogy to laboratory testing of intact rock and measurement of acoustic emissions, the microseismicity can be used to identify, fracture initiation, coalescence of fractures (yield), localization (peak-strength), accumulation of damage (post-peak) and ultimate failure (residual strength) leading to aseismic behaviour. The case studies presented in this thesis provide an opportunity to examine and analyse rock mass failure into the post-peak, through the regional and confined failures at the Williams and the Golden Giant mines, both in the Hemlo camp in Northern Ontario, Canada. At the Williams mine, the progressive failure of a sill pillar region into the post-peak was analysed; relating the seismic event density, combined with numerical modelling and a spatial and temporal examination of the principal components analysis (PCA), to characterize the extent, trend and state of the yielding zone, which formed a macrofracture shear structure. Observations of conventional displacement instrumentation, indicates regional dilation or shear of the rock mass occurs at or prior to the point of ‘disassociation’ (breakdown of stable PCA trends) when approaching the residual strength. At the Golden Giant mine, the complete process from initiation to aseismic behaviour is monitored in a highly stressed and confined pendent pillar. The PCA technique, numerical modelling and focal mechanism studies are used to define significant stages of the failure process, in which a similar macrofracture structure was formed. Temporal observations of key source parameters show significant changes prior to and at the point of coalescence and localization.