Publication: Análisis sísmico de dobles túneles
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2009
Defense date
2009-09-22
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Abstract
Gran parte de las infraestructuras del transporte precisan de estructuras tipo túnel, como por ejemplo en las grandes ciudades, donde la escasez de espacio las hace indispensables o cuando se quieren salvar obstáculos naturales como cadenas montañosas o el mar. Además, en este tipo de infraestructuras, hay una cierta tendencia hacia la configuración de doble túnel más que a uno único de grandes dimensiones. Sin embargo, en el diseño y posible revestimiento de un túnel, suelen tenerse en cuenta, principalmente, las cargas estáticas que actúan y, de una forma mucho más aproximada, las acciones sísmicas que, en algunos casos, pueden resultar sumamente importantes pues pueden producir colapsos inesperados en el túnel, cobrándose así vidas humanas. Por ello, en este trabajo de Tesis Doctoral, haciendo uso de modelos analíticos y de herramientas numéricas, se han estimado las tensiones inducidas en el revestimiento monolítico de un túnel de geometría circular ante un evento sísmico desarrollando, así mismo, modelos numéricos para la estimación del efecto de interacción sísmica entre un par de túneles gemelos. Por tanto, mediante el uso de herramientas numéricas (Elementos Finitos y Diferencias Finitas), y de modelos analíticos, se ha avanzado en el estado de los conocimientos actuales en los siguientes campos del cálculo sísmico en túneles: Estudio transversal (deformación plana): con la puesta a punto de códigos numéricos existentes, y con el desarrollo de uno propio de Elementos Finitos (ESES), se ha demostrado y contabilizado la interacción sísmica perjudicial, en lo que se refiere a esfuerzos generados en los revestimientos de los túneles gemelos. Del mismo modo se han comparado los resultados de los modelos analíticos (planteados para un túnel aislado), con los resultados numéricos, dando recomendaciones en cuanto al uso de aquéllos. · Estudio 3-D numérico del problema: demostrada la importancia de la interacción sísmica entre túneles gemelos, se ha realizado un estudio 3-D, excitando los modelos con ondas sísmicas con frente paralelo y no paralelo a los ejes de los túneles, concluyéndose que la situación más crítica se produce cuando dicho frente es paralelo (estudio transversal) a dichos ejes. También se han efectuado estudios del efecto de la fricción-cohesión-contacto-separación entre el suelo circundante y el revestimiento del túnel, concluyéndose que este fenómeno influye considerablemente en las tensiones que se generan en los revestimientos de los túneles, así como en la interacción sísmica. ____________________________________________
There are a wide range of transport facilities that need tunnel structures, mainly in big cities, where space make them indispensable or when a natural obstacle has to be overcome like mountain ranges or sea. Also, in this type of transport facilities there is a certain tendency toward twin tunnel layout more than a single big one. However, in the design and possible tunnel lining, it is normally taken into account the static loads which act on it and, in a much more simplified way the seismic loads. Nevertheless, the seismic load study is vital to avoid unexpected tunnel collapses, which can generate a high number of deaths. For this reason, in this PhD Thesis, analytical models and numerical tools have been used to estimate induced stresses in circular monolitic tunnel lining when a seismic event happens. In this way, numerical models have been developed for the seismic interaction effect between a set of twin tunnels. Due to the fact that numerical (Finite Elements and Finite Differences), and analytical models are used, an advance has been done in the knowledge of the following fields in seismic calculation of tunnels: · Transverse study (plane strain): the set up of some existing numerical codes, and the develop of a new one of Finite Elements (ESES), have demonstrated and counted damaging seismic interaction, related to efforts generated in the twin tunnel linings. In the same way, a comparison between results of analytical models (for a single tunnel), with numerical ones have been done, and recommendations for the use of the first ones have been given. 3-D numerical study of the problem: once the importance of seismic interaction between twin tunnels has been demonstrated, a 3-D study has been done, applying seismic waves to the models with parallel and non-parallel front to the tunnel axes. The conclusion is that the most adverse situation happens when the front wave is parallel (transverse study) to the tunnel axes. Also, several studies including friction-cohesion-contact-separation phenomena between soil and tunnel lining have been carried out, concluding that these phenomena influences stresses generated in the tunnel linings, and seismic interaction.
There are a wide range of transport facilities that need tunnel structures, mainly in big cities, where space make them indispensable or when a natural obstacle has to be overcome like mountain ranges or sea. Also, in this type of transport facilities there is a certain tendency toward twin tunnel layout more than a single big one. However, in the design and possible tunnel lining, it is normally taken into account the static loads which act on it and, in a much more simplified way the seismic loads. Nevertheless, the seismic load study is vital to avoid unexpected tunnel collapses, which can generate a high number of deaths. For this reason, in this PhD Thesis, analytical models and numerical tools have been used to estimate induced stresses in circular monolitic tunnel lining when a seismic event happens. In this way, numerical models have been developed for the seismic interaction effect between a set of twin tunnels. Due to the fact that numerical (Finite Elements and Finite Differences), and analytical models are used, an advance has been done in the knowledge of the following fields in seismic calculation of tunnels: · Transverse study (plane strain): the set up of some existing numerical codes, and the develop of a new one of Finite Elements (ESES), have demonstrated and counted damaging seismic interaction, related to efforts generated in the twin tunnel linings. In the same way, a comparison between results of analytical models (for a single tunnel), with numerical ones have been done, and recommendations for the use of the first ones have been given. 3-D numerical study of the problem: once the importance of seismic interaction between twin tunnels has been demonstrated, a 3-D study has been done, applying seismic waves to the models with parallel and non-parallel front to the tunnel axes. The conclusion is that the most adverse situation happens when the front wave is parallel (transverse study) to the tunnel axes. Also, several studies including friction-cohesion-contact-separation phenomena between soil and tunnel lining have been carried out, concluding that these phenomena influences stresses generated in the tunnel linings, and seismic interaction.
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Keywords
Túneles, Cáculo de estructuras, Terremotos