Browsing by Author "Thenoux, Guillermo"
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Item Evaluación probabilística del agrietamiento de pavimentos asfálticos en carreteras de Chile(2013) Thenoux, Guillermo; González Vaccarezza, Álvaro; Rodríguez Moreno, M.Los modelos de comportamiento permiten predecir la condición de deterioro de un pavimento y el desarrollo de programas de mantenimiento. Normalmente cuando se evalúa el desempeño de un pavimento a través del modelo de deterioro, el pronóstico corresponde a un valor determinista. Sin embargo, los proyectos de ingeniería de pavimentos tienen un grado de incertidumbre, lo que implica que el adecuado desempeño de la solución no puede ser totalmente asegurado. El objetivo de esta investigación es el de incorporar la probabilidad en el pronóstico del modelo de agrietamiento estructural, para lo cual se utilizó el modelo de iniciación y progresión del agrietamiento del programa HDM-4 bajo diferentes escenarios, definidos según la ubicación geográfica, tránsito y capacidad estructural de carreteras chilenas. Para incorporar la probabilidad en el modelo de comportamiento, se desarrolló un simulador que reproduce el deterioro para un ciclo de veinticinco años de vida, en el cual las variables descriptivas del modelo de comportamiento se representan como variables aleatorias gracias a datos recolectados en terreno. La investigación entrega como resultado una serie de funciones de densidad de probabilidad que representan la respuesta probabilística del modelo de deterioro de catorce grupos de rutas chilenas.Item Evaluation of additional Laboratory Test for Design of Full-Depth Reclamation Mixtures Using Foamed Bitumen(2016) González, Álvaro; Paniagua, Fernando; Thenoux, Guillermo; López, Carlosnormally fix a constant active filler content, and an indirect tensile strength (ITS) test is used to determine the optimum bitumen content. However, it has been reported in the literature that for some materials the ITS test is not sufficiently sensitive to bitumen content. This lack of sensitivity is a problem for the practitioner engineer who has to validate the bitumen content adopted in the mixture design. The main objective of this work is to examine the sensitivity to bitumen content of additional laboratory tests that could complement current design methods based on ITS. The mixtures used in the study were prepared by using three recycled blends of reclaimed asphalt pavement and aggregate that were mixed with bitumen foam contents of 1.25%, 2.5%, and 3.75%. Test results confirmed the low sensitivity of the ITS test, and it was found that the indirect tensile fatigue (ITF) test was the most sensitive among all tests. To explain the higher sensitivity of the ITF test compared with the ITS test, a stress-strain diagram and a simple unidirectional mechanical model were developed. In addition, an S-N fatigue diagram was used to illustrate that at a larger number of load cycles, the effect of the foamed bitumen content is dear, as shown in the experimental work. Overall, the laboratory program and material behavior analysis indicate that when the ITS test does not provide conclusive results, the laboratory program should be complemented with ITF tests to determine the optimum foamed bitumen content with more reliability.Item Interpretation of laboratory and full-scale testing of New Zealand foamed bitumen pavements using finite-element modelling(2012) González Vaccarezza, Álvaro; Cubrinovski, Misko; Alabaster, David; Thenoux, GuillermoA large research project on foamed bitumen (FB) stabilisation was conducted in New Zealand. The project consisted of an extensive laboratory and full-scale testing of FB pavements. The objective of this paper is to interpret the performance of FB pavements by using finite-element (FE) modelling. The mechanical properties of the materials were calculated using testing data and used as material inputs in the FE modelling. The MohrCoulomb and DruckerPrager material models were adopted to calculate plastic deformation, which is related to pavement rutting. Results of the modelling indicate that increasing the FB content increases the tensile strength and modulus of the pavements, reducing the plastic deformations in the subgrade and the stabilised layer. In addition, adding FB reduces sensitivity to rutting when pavement is overloaded or the asphalt surface layer is crackedItem Probabilistic assessment of asphalt pavement design(2016) Rodríguez Moreno, M.; Thenoux, Guillermo; González, ÁlvaroIn Chile, as in many South American countries, AASHTO-93 is the current official method for the design of asphalt pavements. The method gives an estimated number of 80 kN standard axle loads (W18) that the pavement can withstand for a certain serviceability. A safety factor is then applied to W18 to take into account the confidence level and the estimated variance of the inputs used in the method, whereby the magnitude of the structure's life cycle is estimated. Normally, data used in the AASHTO-93 method are assumed to be deterministic, disregarding their random nature. This paper presents a probabilistic assessment of the AASHTO-93 pavement design method under Chilean conditions, which provides a set of probability density functions (PDFs) that allow a probabilistic estimation of the pavement life cycle in terms of the value W18. To achieve the goal, we developed a simulation model based on a sample of 13 groups of roads located throughout Chile.Item Stiffness Evolution of Granular Materials Stabilized with Foamed Bitumen and Cement(2013) Halles, Felipe; Thenoux, Guillermo; González Vaccarezza, ÁlvaroFrom the literature, it is possible to find two trends regarding the stiffness evolution of foamed bitumen stabilized-recycled mixtures. The first trend indicates that once the foamed bitumen mix reaches a constant value because of the curing process, the stiffness decreases with time because of load cycles. The second trend indicates that stiffness remains constant after the curing process. In this research, the stiffness evolution of foamed bitumen mixes stabilized with different bitumen and cement contents was studied. The stiffness was measured by using the indirect tensile fatigue test. Results indicated that once the foamed bitumen mix reached a constant value because of the curing process, stiffness decreased or remained constant depending on the stress level applied to the foamed bitumen layer. If the stress level is lower than a specific value, the stiffness of the mix will remain constant at a value extremely close to the initial stiffness. If the stress level is greater than a specific value, the stiffness of the mix will decrease gradually. In addition, the reduction rate of the stiffness will be greater with higher stress level. The analysis of results from mixes with different bitumen and cement contents allows identification of the effect of both stabilizing agents in the long-term stiffness evolution.