Control de asentamientos en terraplenes construidos sobre suelo fino por medio de métodos de mejoramiento de suelos basados en vibro-sustitución
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Fecha
2017
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es
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Universidad Andrés Bello
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Licencia CC
Licencia CC
Resumen
Los suelos de grano fino se caracterizan en general, por presentar una elevada compresibilidad y ser altamente sensibles a los cambios de humedad. Por ello, uno de los aspectos críticos para el diseño y construcción de las estructuras que deben apoyarse sobre este tipo de materiales tiene que ver con el control de asentamientos. Cuando el suelo es particularmente compresible y la potencia de los estratos de material fino impide considerar el reemplazo de suelos como una solución factible, se puede recurrir a los denominados métodos de mejoramiento de suelo.
La técnica de vibro-sustitución, que resulta particularmente efectiva en suelos finos, consiste en la introducción de una sonda que puede penetrar en el material a grandes profundidades. Así, por medio de la adición de agregado grueso vibrado y compactado por capas (típicamente grava), se consigue una serie de columnas discretas que permiten reducir la compresibilidad y darle mayor rigidez y resistencia al corte al terreno.
En este trabajo se busca evaluar cómo el uso del método de vibro-sustitución con columnas de grava puede ayudar al control de asentamientos en terraplenes construidos sobre depósitos de suelo fino. Se estudian diferentes escenarios, utilizando tanto métodos simplificados como modelos numéricos de elementos finitos, para cuantificar la influencia de parámetros tales como diámetro y rigidez de las columnas, propiedades de la grava, y distribución en planta del arreglo de columnas.
Finalmente, se busca establecer relaciones entre las características de la solución adoptada y la reducción de asentamientos esperada en el terreno, medida como fracción del asentamiento que se produciría en el suelo sin considerar mejoramiento alguno.
In general, fine-grained soils are highly compressible and sensitive to changes in moisture content. Therefore, one of the critical aspects for both design and construction of structures on this type of materials has to do with the control of induced settlements. When the soil is particularly compressible and the thickness of fine soil materials does not allow to consider soil replacement as a feasible solution, the so-called ground improvement methods can be utilized. The vibro-replacement technique, which is particularly effective in fine-grained soils, consist on a probe that can be introduced deeply into the soil. Thus, by adding coarse aggregate in incremental lifts using both vibration and compaction (typically, gravel), a series of discrete columns (called stone columns) that reduce compressibility and provide increased resistance and stiffness to the soil are generated. The main goal of this work is to evaluate how the use of the vibro-replacement method can help controlling induced settlements in embankments built on soft soils. Different scenarios, using both simplified methods and numerical finite-element models, are utilized to analyze the influence of several parameters such as diameter and stiffness of columns, properties of the gravel material, and plan distribution of columns, on the results obtained. Finally, the idea is to establish relationships between the characteristics of the improvement solution and the reduction of the expected settlements in soil, measured as a fraction of those that could be induced without any improvement.
In general, fine-grained soils are highly compressible and sensitive to changes in moisture content. Therefore, one of the critical aspects for both design and construction of structures on this type of materials has to do with the control of induced settlements. When the soil is particularly compressible and the thickness of fine soil materials does not allow to consider soil replacement as a feasible solution, the so-called ground improvement methods can be utilized. The vibro-replacement technique, which is particularly effective in fine-grained soils, consist on a probe that can be introduced deeply into the soil. Thus, by adding coarse aggregate in incremental lifts using both vibration and compaction (typically, gravel), a series of discrete columns (called stone columns) that reduce compressibility and provide increased resistance and stiffness to the soil are generated. The main goal of this work is to evaluate how the use of the vibro-replacement method can help controlling induced settlements in embankments built on soft soils. Different scenarios, using both simplified methods and numerical finite-element models, are utilized to analyze the influence of several parameters such as diameter and stiffness of columns, properties of the gravel material, and plan distribution of columns, on the results obtained. Finally, the idea is to establish relationships between the characteristics of the improvement solution and the reduction of the expected settlements in soil, measured as a fraction of those that could be induced without any improvement.
Notas
Tesis (Ingeniero Civil)
Palabras clave
Terraplenes, Diseño y Construcción