This research provides an insight into the quality of a soil sample during the penetration of a soil sampler. The investigation of the mechanical disturbances in a clay soil is conducted by using an updated Lagrangian finite element formulation with the 2nd Piola-Kirchhoff stress rate (the Truesdell stress increment) to account for the large deformation behavior near the sampling tube. The penetration of the sampler is simulated by spliting a group of nodes ahead of the penetration route up to a sufficient depth and applying incremental deformation to match the geometric configuration of the sampling tube. Consolidation effect is included to account for the rate of penetration. Thin-layer elements are added into the inside wall of the sampling tube to model the soil-sampler interface. The modified Cam-clay model is used to simulate the behavior of the soils. An experimental study was conducted to study the variations of stresses and pore water pressures at the soil-sampler interface. The numerical results show that (1) soil samples are subjected to three distinct stages of vertical strain history, compression-extension-recompression. The first stage of compression, in particular, causes irrecoverable changes in the virgin soil properties of the soil; (2) the undrained shear strength of a disturbed sample reconsolidated to the in situ stress condition is larger than the virgin soil for normally consolidated soils but it is smaller for over consolidated soils; (3) the sampling disturbances due to friction at the soil-sampler interface increase as the sampler penetrates the soil. As a result, long samples will be seriously degraded; (4) the increase of the rate of penetration can reduce the degree of disturbances; (5) the piston sampler induces much larger disturbances than the open-drive sampler.

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Ingeniero Civil / El presente trabajo de título analiza el método de consolidación por vacío y su aplicabilidad para el mejoramiento de un relave integral. El estudio se basa en la comparación de resultados obtenidos a partir de un modelo experimental, modelaciones numéricas de elementos finitos y soluciones analíticas recopiladas de la literatura técnica. El modelo experimental aplica succión generada por una bomba de vacío sobre una columna de relave integral saturado y monitorea la evolución temporal de la deformación vertical, simulando la aplicación de esta técnica en suelos depositados en la cubeta de un tranque de relaves. Además, se realizan simulaciones numéricas de elementos finitos con el software Abaqus para reproducir las condiciones del modelo experimental y poder capturar las mediciones de laboratorio. El comportamiento elasto-plástico del material se simula con el modelo constitutivo Cam-Clay Modificado (MCCM). La calibración de los parámetros de compresibilidad y de conductividad hidráulica del material se realiza con ensayos de laboratorio considerando dos estados de depositación y otros parámetros se adoptan de los trabajos de Cifuentes y Verdugo (2007) y Conejera (2016). La aplicación de -80 kPa de vacío induce deformaciones verticales en la columna de relave integral que son equivalentes a las inducidas por la aplicación de 3,5 - 4 metros de material de relleno. El fenómeno de consolidación de vacíos se puede simular numéricamente con un software de elementos finitos y el uso de un modelo constitutivo elasto-plástico, como Cam-Clay Modificado (MCCM). Los parámetros críticos para modelar apropiadamente el fenómeno son los parámetros de compresibilidad y la conductividad hidráulica del material. Si bien estos parámetros se pueden estimar con ensayos estándares de laboratorio, se requieren algunos ajustes para estimar el asentamiento máximo y el tiempo de consolidación.

M.Tech. (Industrial Design) / The research project entitled: The Analysis of Clay Materials for use in a Ceramic Studio was undertaken in order to give a quantitative base to the understanding of clay materials and their role in clay bodies. The project consists of analysing the clay materials as they are supplied, using technically sophisticated equipment. A set of data for each of the nine chosen clays was assembled and then correlated for easier comparison. The clay materials were then mixed into clay bodies using a set proportion in order that a comparison of the nine clay bodies could be made and related to the data assembled for the clay materials. The data collected, as well as the ceramic calculations used in the research project were entered into the "Insight" Ceramic software programme for use in the studio. This data base will be the foundation for ongoing research into ceramic materials.

The major concern of this study is an attempt to analyze the attitudes.of Henry Clay, United States Congressman and Senator from Kentucky, 1807-1852, and three time presidential candidate, concerning the institution of slavery by examining its effects upon his political career from 1798 to 1850. The major conclusions of this study are that early in his life Clay made an intellectual commitment that slavery was wrong and maintained this abstract view of the institution until his death. However, Clay never took an active stand against slavery for three reasons: he believed that an antislavery stand would destroy his political career; he realized the explosiveness of the slavery issue as early as 1799, and his misguided love for the Union forced him to attempt to suppress the issue; and Clay was a racist who did not wish to see the United States populated with a sizable number of free blacks.