Contribution to Theme A of the Benchmark Workshop: Effect of Concrete Swelling on the Equilibrium and Displacements of an Arch Dam

The Kariba dam is undergoing concrete expansion as a result of an alkali-aggregate reaction. The model adopted to simulate the process is explained in the paper; it is based on the model first proposed by Ulm et al, as later modified by Saouma and Perotti. It has been implemented in the commercial finite element code Abaqus and applied to solve the benchmark problem. The parameters of the model were calibrated using the data recorded up to 1995. The calibrated model was then used for predicting the evolution of the dam up to the present date. Apart from this prediction the paper offers a number of conclusions, such as the fact that the stress level appears to have a major influence on the expansion process; and it presents some suggestions to improve the formulation of the benchmark, such as providing temperature data and widening the locations and conditions of the data employed in the calibration

Effect of Concrete Swelling on the Equilibrium and Displacements of an Arch Dam

The Kariba dam is undergoing concrete expansion as a result of an alkali-aggregate reaction. The model adopted to simulate the process is explained in the paper; it is based on the model first proposed by Ulm et al, as later modified by Saouma and Perotti. It has been implemented in the commercial finite element code Abaqus and applied to solve the benchmark problem. The parameters of the model were calibrated using the data recorded up to 1995. The calibrated model was then used for predicting the evolution of the dam up to the present date. Apart from this prediction the paper offers a number of conclusions, such as the fact that the stress level appears to have a major influence on the expansion process; and it presents some suggestions to improve the formulation of the benchmark, such as providing temperature data and widening the locations and conditions of the data employed in the calibration

Sistemas de control de roturas en presas y caracterizaci��n de sistemas hidr��ulicos

Este proyecto nace de la necesidad de automatizar el estudio de sistemas hidr��ulicos y de control de roturas en presas. Para realizar el estudio de sistemas hidr��ulicos se usar��n un n��mero indeterminado de sensores de nivel, presi��n y caudal. El n��mero de sensores que se pueden utilizar viene determinado por el material disponible. Estos sensores se conectar��n a unas tarjetas de National Instruments modelo NI 9208 y ��stas a su vez a un chasis modelo CompactDAQ NI-9174 con cuatro ranuras. Conectando este chasis al ordenador podremos obtener los datos provenientes de los sensores. Tambi��n se podr�� controlar una v��lvula para determinar la cantidad de agua que fluye en nuestro experimento. Est�� v��lvula est�� conectada a una tarjeta NI-9264 que se conectar�� al chasis en su ��ltima posici��n Para detectar y estudiar posibles roturas en presas se dispone de un motor y un l��ser con los cuales se puede barrer la superficie de una presa y obtener una imagen en tres dimensiones de la misma procesando los datos provenientes del laser. Para recoger los datos de los sensores y controlar una v��lvula se ha desarrollado una aplicaci��n utilizando LabVIEW, un programa creado por National Instruments. Para poder controlar el motor y el l��ser se parte de una aplicaci��n que ya estaba realizada en LabVIEW. El objetivo ha sido detectar y corregir una serie de errores en la misma. Dentro del proyecto, adem��s de la explicaci��n detallada de la aplicaci��n para los sensores y la v��lvula, y las pruebas realizadas para detectar y corregir los errores de la aplicaci��n del l��ser y el motor, existe: una breve introducci��n a la programaci��n en LabVIEW, la descripci��n de los pasos realizados para el conexionado de los sensores con las tarjetas, los manuales de usuario de las aplicaciones y la descripci��n de los equipos utilizados. This project stars from the need to automate the study of hydraulic systems and control dam breaks. For the study of hydraulic systems it will be used an unspecified number of level, pressure and flow sensors. The number of sensors that can be used is determined by the available material. These sensors are connected to a NI 9208 National Instruments target and these cards to a NI-9174 CompactDAQ chassis with four slots. Connecting the chassis to a computer we will obtain data from the sensors. We also can control a valve to determine the amount of water flowing in our experiment. This valve is connected to a NI-9264 card and this card to the last position of the chassis. To detect and study dams breakage it used a motor and a laser. With these two devices we can scan the surface of a dam and obtain a three-dimensional image processing data from the laser. To collect data from the sensors and control the valve it has developed an application using LabVIEW, a program created by National Instruments. To control the motor and the laser it is used an application that was already created using LabVIEW. The aim of this part has been detect and correct a number of errors in this application. Within the project, in addition to the detailed explanation of the application for sensors and valve, and tests to detect and correct errors in the application of lasers and the motor, there is: a brief introduction to programming in LabVIEW, the description of the steps taken for connecting the sensors with cards, user manuals and application description of the equipment used.

Estudio de la reactividad ��lcali-s��lice originada por componentes reactivos minoritarios

El objetivo de la presente tesis se enmarca dentro del estudio del estado de hormigones de presas, desarrollado en los ��ltimos a��os en el Laboratorio Central del CEDEX, en el que se ratifica que una de las causas m��s importantes del deterioro de obras hidr��ulicas en Espa��a es la reacci��n ��lcali-s��lice. La tesis que se presenta pretende contribuir al mejor conocimiento de la reacci��n ��lcali s��lice con fines normativos preventivos, abordando los aspectos relativos a la identificaci��n de ��ridos reactivos en el hormig��n. El conocimiento de los ��ridos reactivos en Espa��a (origen de la reactividad, tipos de reacci��n y su comportamiento, as�� como las herramientas disponibles para su detecci��n) es imprescindible para evitar la futura aparici��n de esta patolog��a en nuevas estructuras, ya sea evitando el uso de ��ridos reactivos o tomando las medidas preventivas necesarias si su utilizaci��n es inevitable. A partir del Estudio Bibliogr��fico realizado se han detectado diversas lagunas en la identificaci��n y caracterizaci��n de ��ridos de reacci��n r��pida, cuya caracter��stica principal es que son reactivos con concentraciones muy bajas de diferentes componentes reactivos. Para resolver las lagunas identificadas se ha planeado un estudio experimental, consistente en el an��lisis de ��ridos cuya reactividad es conocida porque han sido empleados en obras afectadas por la reacci��n ��lcali s��lice. Sobre el ��rido grueso extra��do de estas estructuras se han realizado una serie de ensayos normalizados (estudio petrogr��fico, ensayo acelerado de probetas de mortero, ensayo Gel Pat y ensayos qu��micos). El an��lisis de los resultados experimentales ha permitido conocer las limitaciones reales en ��ridos reactivos espa��oles de las diferentes t��cnicas existentes, tratando de minimizarlas para ��ridos cuya reactividad es debida a componentes minoritarios (��ridos de reacci��n r��pida). Adem��s, se ha evaluado la utilizaci��n de la difracci��n de rayos X (no normalizada) y la creaci��n de un nuevo ensayo (Gel Pat Modificado). Finalmente, el estudio experimental ha permitido fijar una metodolog��a de ensayo para el estudio de ��ridos reactivos por su contenido en componentes minoritarios (��ridos de reacci��n r��pida). The objective of this Thesis fits into the research program developed in CEDEX the last years and focused on the durability of concrete in Dams. This research work confirms that one of the main problems related to the deterioration of hydraulic structures is the alkali silica reaction. This Thesis aims to contribute to a better understanding of alkali-silica reaction, for preventive regulation purposes, considering the aspects related to the identification of reactive aggregates. The knowledge of Spanish reactive aggregates (origin of the reactivity, types of reaction and their behavior, and the tools available to detect and describe them) is essential to avoid the appearance of this pathology in new structures, either not using the reactive aggregate or taking the necessary preventive measures available in bibliography if the use of the reactive aggregate is inevitable. From the State-of ���the-Art developed, several gaps have been detected in the detection and description of rapid reactive aggregates, which main characteristic if that they are reactive with low content of some reactive components. An experimental programme has been designed to solve these gaps, consisting on studying the reactivity of aggregates used in Spanish structures affected by the alkali silica reaction. Several Standard Tests have been carried out on coarse aggregates removed from the affected structures (Petrographic description, Accelerated Mortar Bar Test, Gel Pat Test and Chemical Tests). The analysis of the results obtained in Spanish reactive aggregates allows to know the advantages and limitations of each test, trying to minimize the disadvantages to detect Spanish reactive aggregates because of the minority content of rapid reactive components (rapid reactive aggregates). Moreover, X ray diffraction (not standardized) has been tested to detect rapid reactive aggregates and also a new test has been developed for the same purpose (Optimized Gel Pat Test). Finally, the experimental programme has made possible to define a methodology for detection of Spanish rapid reactive aggregates.

Mejora de la seguridad de las presas de escollera frente a percolaci��n accidental mediante protecciones tipo repi��

Esta tesis doctoral es el fruto de un trabajo de investigaci��n cuyo objetivo principal es definir criterios de dise��o de protecciones en forma de repi�� en presas de materiales sueltos cuyo espald��n de aguas abajo est�� formado por escollera. La protecci��n propuesta consiste en un relleno de material granular situado sobre el pie de aguas abajo de la presa y formado a su vez por una escollera con caracter��sticas diferenciadas respecto de la escollera que integra el espald��n de la presa. La funci��n de esta protecci��n es evitar que se produzcan deslizamientos en masa cuando una cantidad de agua anormalmente elevada circula accidentalmente por el espald��n de aguas abajo de la presa por distintos motivos como pueden ser el vertido por coronaci��n de la presa o la p��rdida de estanqueidad del elemento impermeable o del cimiento. Seg��n los datos de la International Commission on Large Dams (ICOLD 1995) el 70% de las causas de rotura o aver��a grave en presas de materiales sueltos en el mundo est��n dentro de las que se han indicado con anterioridad. Esta circulaci��n accidental de agua a trav��s del espald��n de escollera, t��picamente turbulenta, se ha denominado en esta tesis percolaci��n (���through flow���, en ingl��s) para diferenciarla del t��rmino filtraci��n, habitualmente utilizada para el flujo laminar a trav��s de un material fino. El fen��meno f��sico que origina la rotura de presas de materiales sueltos sometidas a percolaci��n accidental es complejo, entrando en juego diversidad de par��metros, muchas veces no deterministas, y con acoplamiento entre procesos, tanto de filtraci��n como de arrastre y deslizamiento. En esta tesis se han realizado diferentes estudios experimentales y num��ricos con objeto de analizar el efecto sobre el nivel de protecci��n frente al deslizamiento en masa que producen los principales par��metros geom��tricos que definen el repi��: la anchura de la berma, el talud exterior y su altura m��xima desde la base. Tambi��n se han realizado estudios sobre factores con gran influencia en el fen��meno de la percolaci��n como son la anisotrop��a del material y el incremento de los caudales unitarios en el pie de presa debidos a la forma de la cerrada. A partir de los resultados obtenidos en las distintas campa��as de modelaci��n f��sica y num��rica se han obtenido conclusiones respecto a la efectividad de este tipo de protecci��n para evitar parcial o totalmente los da��os provocados por percolaci��n accidental en presas de escollera. El resultado final de la tesis es un procedimiento de dise��o para este tipo de protecciones. Con objeto de completar los criterios de dimensionamiento, teniendo en cuenta los mecanismos de rotura por erosi��n interna y arrastre, se han incluido dentro del procedimiento recomendaciones adicionales basadas en investigaciones existentes en la bibliograf��a t��cnica. Finalmente, se han sugerido posibles l��neas de investigaci��n futuras para ampliar el conocimiento de fen��menos complejos que influyen en el comportamiento de este tipo de protecci��n como son el efecto de escala, la anisotrop��a de la escollera, las leyes de resistencia que rigen la filtraci��n turbulenta a trav��s de medios granulares, los efectos de cimentaciones poco competentes o la propia caracterizaci��n de las propiedades de la escollera de presas. This thesis is the result of a research project that had the main objective of defining criteria to design rockfill toe protections for dams with a highly���permeable downstream shoulder. The proposed protection consists of a rockfill toe berm situated downstream from the dam with specific characteristics with respect to the rockfill that integrates the shoulder of the main dam. The function of these protections is to prevent mass slides due to an abnormally high water flow circulation through the dam shoulder. This accidental seepage flow may be caused by such reasons as overtopping or the loss of sealing at the impervious element of the dam or its foundation. According to data from the International Commission on Large Dams (ICOLD 1995), 70% of the causes of failure or serious damage in embankment dams in the world are within that described previously. This accidental seepage of water through the rockfill shoulder, typically turbulent, is usually called through���flow. The physical phenomenon which causes the breakage of the rockfill shoulder during such through���flow processes is complex, involving diversity of parameters (often not deterministic) and coupling among processes, not only seepage but also internal erosion, drag or mass slide. In this thesis, numerical and experimental research is conducted in order to analyze the effects of the main parameters that define the toe protection, i.e. the toe crest length, its slope and maximum height. Additional studies on significant factors which influence the seepage, such as the anisotropy of the material and the increase of the unit flows at the dam toe due to the valley shape are also performed. In addition, conclusions regarding the effectiveness of this type of protection are obtained based on the results of physical and numerical models. The main result of the thesis is a design procedure for this type of protection to avoid mass sliding. In order to complete the design criteria, additional recommendations about internal and external erosion based on the state of the art are included. Finally, new lines of research are suggested for the future to expand the level of knowledge of the complex phenomena that influence the behavior of this type of protection, such as the effects of scale, rockfill anisotropy, non���linear seepage laws in turbulent seepage through granular media, effects of erodible foundations, or new procedures to characterize the properties of dam rockfill as a construction material.

Building a New Water Culture in Spain

For over 100 years, water policy and man�� agement in Spain have been instruments of economic and social transformation. Sig�� nificant public and private investments in water supply infrastructures have equipped Spain with over 1,200 major dams, 20 major desalination plants ? with more under construction ? and several inter��basin water transfers. The system has been apparently very successful, with an increase in overall water availability, strong associated eco�� nomic development and few urban water supply shortages. This success has been supported by a widespread consensus among a strong and largely closed water policy community made up of water manag�� ers, irrigators, electric (hydropower) utilities and developers.

Inspecci��n t��cnica de la presa Santa Marta, mediante medidas subacu��ticas de potencial espont��neo

Las filtraciones de agua, con la consecuente erosi��n interna en presas de materiales sueltos, es una de las causas principales de fallos y accidentes. Las consecuencias del fallo de estas estructuras, pueden ser, p��rdidas tanto econ��micas como de vidas humanas. Por lo cual en este proyecto se describe la aplicaci��n de un m��todo de prospecci��n geof��sica no invasiva, medidas de potencial espont��neo, para detectar posibles filtraciones de agua en el cuerpo de la presa. El flujo de agua a trav��s de un material poroso y permeable crea un campo de potencial el��ctrico de una magnitud de decenas o centenas de milivoltios, el cual puede ser medido y as�� detectar infiltraciones de agua en presas de materiales sueltos. Se ha aplicado esta t��cnica en la Presa Santa Marta, y mediante una interpretaci��n cualitativa de los datos medidos, tomados en la cara aguas arriba de la presa (medidas subacu��ticas), se logr�� identificar un flujo de agua vertical y otro subhorizontal, que estaban ingresando en el cuerpo de la presa, los cuales estaban causando erosi��n interna y la formaci��n de una tubificaci��n. ABSTRACT Water leakages and internal erosion in embankment dams is one of the main causes of failures and accidents. The consequences of the failure of these structures may cause losses both, economical and of human lives. Therefore, this project describes the application of a noninvasive geophysical prospecting method, self potential measurements, to detect water leakages in the body of the dam. Water flow through a porous and pervious medium creates an electric potential field with a magnitude of tens or hundreds of milivolts, which can be measured and thus detect water leakage in embankment dams. This technique has been applied to the Santa Marta dam, and through a qualitative self potential data interpretation, of the measurements obtained in an upstream direction (underwater measurements), a vertical and sub horizontal water flows entering in the body dam were identified, which were causing internal erosion and developing a piping

Simulation of Temperatures and Stresses during Construction of a RCC Dam

Se describen las variaciones de temperaturas y de tensiones durante la construcci��n de presas de hormig��n compactado. The curing of concrete is an exothermic process. The heat of hydration generated induces temperature increases in the concrete, which will disappear in the long term by heat conduction in the concrete mass and thermal exchanges with the environment. The problem is of particularly interest for large concrete masses, as is the case of dams, because the time involved in the heat diffusion process grows with the square of the dimensions and a hotter dam interior implies the possibility of cracking the exposed surfaces of the dam. The Cuira dam, currently being built in Venezuela using roller compacted concrete, is a 134 m high, arch-gravity dam. In support of the design, different strategies were analysed, including various combinations of cooling of the water and the aggregate in order to achieve acceptable results. The calculations were conducted with Abaqus, taking into account all the necessary mechanical and thermal characteristics, as well as the relevant non-linearities. The analyses led to the conclusion that no cooling was required, even taking into account the stress state imposed by an early and rapid filling of the reservoir.

Concrete Swelling in a Double Curvature Dam

Se describe el problema del hinchamiento del hormig��n en las presas de doble curvatura. Several chemical reactions are able to produce swelling of concrete for decades after its initial curing, a problem that affects a considerable number of concrete dams around the world. The object of the work reported is to simulate the underlying mechanisms with sufficient accuracy to reproduce the past history and to predict the future evolution reliably. Having studied the available formulations, that considered to be more promising was adopted and introduced via user routines in a commercial finite element code. It is a non isotropic swelling model,compatible with the cracking and other non-linearities displayed by the concrete. The paper concentrates on the work conducted for a double-curvature arch dam. The model parameters were determined on the basis of some parts of the dam���s monitored histories, reliability was then verified using other parts and, finally, predictions were made about the future evolution of the dam and its safety margin.

Fluid-Structure Interaction in Civil Engineering Structures

The problems being addressed involve the dynamic interaction of solids (structure and foundation) with a liquid (water). Various numerical procedures are reviewed and employed to solve the problem of establishing the expected response of a structure subjected to seismic excitations while duly accounting for those interactions. The methodology is applied to the analysis of dams, lock gates, and large storage tanks, incorporating in some cases a comparison with the results produced by means of simplified analytical procedures.

Survey on integration of Applied Geology and Geomorphology in Civil Engineering curricula in the framework of the European Higher Education Area (EHEA) by using practical trips

The engineer must have sufficient theoretical knowledge to be applied to solve specific problems, with the necessary capacity to simplify these approaches, and taking into account factors such as speed, simplicity, quality and economy. In Geology, its ultimate goal is the exploration of the history of the geological events through observation, deduction, reasoning and, in exceptional cases by the direct underground exploration or experimentation. Experimentation is very limited in Geology. Reproduction laboratory of certain phenomena or geological processes is difficult because both time and space become a large scale. For this reason, some Earth Sciences are in a nearly descriptive stage whereas others closest to the experimental, Geophysics and Geochemistry, have assimilated progress experienced by the physics and chemistry. Thus, Anglo-Saxon countries clearly separate Engineering Geology from Geological Engineering, i.e. Applied Geology to the Geological Engineering concepts. Although there is a big professional overlap, the first one corresponds to scientific approach, while the last one corresponds to a technological one. Applied Geology to Engineering could be defined as the Science and Applied Geology to the design, construction and performance of engineering infrastructures in and field geology discipline. There has been much discussion on the primacy of theory over practice. Today prevails the exaggeration of practice, but you get good workers and routine and mediocre teachers. This idea forgets too that teaching problem is a problem of right balance. The approach of the action lines on the European Higher Education Area (EHEA) framework provides for such balance. Applied Geology subject represents the first real contact with the physical environment with the practice profession and works. Besides, the situation of the topic in the first trace of Study Plans for many students implies the link to other subjects and topics of the career (tunnels, dams, groundwater, roads, etc). This work analyses in depth the justification of such practical trips. It shows the criteria and methods of planning and the result which manifests itself in pupils. Once practical trips experience developed, the objective work tries to know about results and changes on student���s motivation in learning perspective. This is done regardless of the outcome of their knowledge achievements assessed properly and they are not subject to such work. For this objective, it has been designed a survey about their motivation before and after trip. Survey was made by the Unidad Docente de Geolog��a Aplicada of the Departamento de Ingenier��a y Morfolog��a del Terreno (Escuela T��cnica Superior de Ingenieros de Caminos, Canales y Puertos, Universidad Polit��cnica de Madrid). It was completely anonymous. Its objective was to collect the opinion of the student as a key agent of learning and teaching of the subject. All the work takes place under new teaching/learning criteria approach at the European framework in Higher Education. The results are exceptionally good with 90% of student���s participation and with very high scores in a number of questions as the itineraries, teachers and visited places (range of 4.5 to 4.2 in a 5 points scale). The majority of students are very satisfied (average of 4.5 in a 5 points scale).

Estudio de redes WSN y su aplicaci��n a la ingenier��a civil

Las redes inal��mbricas est��n experimentando un gran crecimiento en el campo de la instrumentaci��n electr��nica. En concreto las redes de sensores inal��mbricas (WSN de Wireless Sensor Network) suponen la opci��n m��s ventajosa para su empleo en la instrumentaci��n electr��nica ya que sus principales caracter��sticas se acoplan perfectamente a las necesidades. Las WSN permiten la utilizaci��n de un n��mero relativamente alto de nodos, est��n orientadas a sistemas de bajo consumo y funcionamiento con bater��as y poseen un ancho de banda adecuado para las necesidades de la instrumentaci��n electr��nica. En este proyecto fin de carrera se ha realizado un estudio de las tecnolog��as inal��mbricas disponibles, se han comparado y se ha elegido la tecnolog��a ZigBeeTM por considerarse la m��s adecuada y la que m��s se ajusta a las necesidades descritas. En el desarrollo de mi vida profesional se han conectado dos campos te��ricamente distantes como son la instrumentaci��n electr��nica y la ingenier��a civil. En este proyecto se hace una descripci��n de la instrumentaci��n que se utiliza para controlar estructuras como presas, t��neles y puentes y se proponen casos pr��cticos en los que las redes WSN aportan valor a��adido a instrumentaci��n actual y a los sistemas de comunicaciones utilizados. Se definen tanto los sistemas de comunicaciones utilizados actualmente como una serie de sensores utilizados para medir los principales par��metros a controlar en una obra civil. Por ��ltimo se ha desarrollado una aplicaci��n de prueba de una red ZigBeeTM basada en equipos comerciales del fabricante Digi. consiste en una aplicaci��n desarrollada en entorno web que maneja de forma remota, a trav��s de Internet, las entradas y salidas digitales y anal��gicas de los nodos que forman la red. Se forma una red ZigBeeTM con un coordinador, un router y un dispositivo final. El Coordinador est�� integrado en un Gateway que permite acceder a la red ZigBeeTM a trav��s de internet y conocer el estado de los nodos que forman la red. Con los comandos adecuados se puede leer el estado de las entradas y salidas anal��gicas y digitales y cambiar el estado de una salida digital. ABSTRACT. Wireless networks are experiencing tremendous growth in the field of electronic instrumentation. In particular wireless sensor networks represent the most advantageous for use in electronic instrumentation since its main characteristics fit perfectly to the needs. The WSN allow the use of a relatively large number of nodes, are aimed at low-power systems and battery operation and have an adequate bandwidth for the needs of electronic instrumentation. In this project has made a study of available wireless technologies have been compared and chosen ZigBeeTM technology was considered the most appropriate to the needs described. In the course of my professional life have connected two fields are theoretically distant as electronic instrumentation and civil engineering. In this project, there is a description of the instrumentation used to control structures such as dams, tunnels and bridges and proposes practical cases in which WSN networks add value to current instrumentation and communications systems used. There are defined as communications systems now being used as a set of sensors used to measure the main parameters to be controlled in a civil structure. Finally, I have developed a test application based ZigBeeTM networking equipment maker Digi trading. It consists of a Web-based application developed to manage remotely, via the Internet, the digital and analog inputs and outputs nodes forming the network. ZigBeeTM It forms a network with a coordinator, router and end device. The Coordinator is built into a gateway that allows access to the ZigBeeTM network through internet and know the status of the nodes forming the network. With the appropriate command can read the status of the digital inputs and outputs and change the state of a digital output.

Esfuerzos inducidos en presas, arco-gravedad en operaci��n por la acci��n t��rmica medioambiental : una aportaci��n a su an��lisis y evaluaci��n

Cyclic fluctuations of the atmospheric temperature on the dam site, of the water temperature in the reservoir and of the intensity of solar radiation on the faces of the dam cause significant stresses in the body of concrete dams. These stresses can be evaluated first by introducing in analysis models a linear temperature distribution statically equivalent to the real temperature distribution in the dam; the stress val��es obtained from this first step must be complemented (especially in the ��rea of dam faces) with the stress val��es resuiting from the difference between the real temperature law and the linear law at each node. In the case of arch gravity dams, and because of their characteristics of arch dam featuring a thick section, both types of temperature-induced stresses are of similar importance. Thermal stress val��es are directly linked to a series of factors: atmospheric and water temperature and intensity of solar radiation at dam site, site latitude, azimuth of the dam, as well as geometrical characteristics of the dam and thermal properties of concrete. This thesis first presents a complete study of the physical phenomenon of heat exchange between the environment and the dam itself, and establishes the participation scheme of all parameters involved in the problem considered. A detailed documental review of available methods and techniques is then carried out both for the estimation of environmental thermal loads and for the evaluation of the stresses induced by these loads. Variation ranges are also established for the main parameters. The definition of the geometrical parameters of the dam is provided based on the description of a wide set of arch gravity dams built in Spain and abroad. As a practical reference of the parameters defining the thermal action of the environment, a set of zones, in which thermal parameters reach homogeneous val��es, was established for Spain. The mean valu�� and variation range of atmospheric temperature were then determined for each zone, based on a series of historical val��es. Summer and winter temperature increases caused by solar radiation were also defined for each zone. Since the hypothesis of thermal stratification in the reservoir has been considered, m��ximum and m��nimum temperature val��es reached at the bottom of the reservoir were determined for each climatic zone, as well as the law of temperature variation in function of depth. Various dam-and-foundation configurations were analysed by means of finite element 3D models, in which the dam and foundation were each submitted to different load combinations. The seasonal thermal behaviour of sections of variable thickness was analysed through the application of numerical techniques to one-dimensional models. Contrasting the results of both analyses led to conclusions on the influence of environmental thermal action on the stress conditions of the structure. Las oscilaciones peri��dicas de la temperatura ambiente en el emplazamiento y de la temperatura del agua en el embalse, as�� como de la incidencia de la radiaci��n solar sobre los paramentos de la presa, son causa de tensiones importantes en el cuerpo de las presas de hormig��n. Estas tensiones pueden ser evaluadas en primer lugar introduciendo en los modelos tridimensionales de an��lisis, distribuciones lineales de temperatura est��ticamente equivalentes a las correspondientes distribuciones reales en el cuerpo de la presa; las tensiones as�� obtenidas han de complementarse (sobre todo en las cercan��as de los paramentos) con tensiones cuyo origen est�� en la temperatura diferencia entre la ley real y la lineal en cada punto. En el caso de las presas arco-gravedad y en raz��n de su doble caracter��stica de presas arco y de secci��n gruesa, ambas componentes de la tensi��n inducida por la temperatura son de magnitud similar. Los valores de estas tensiones de origen t��rmico est��n directamente relacionados con la temperatura del emplazamiento y del embalse, con la intensidad de la insolaci��n, con la latitud y el azimut de la presa, con las caracter��sticas geom��tricas de la estructura y con las propiedades t��rmicas del hormig��n. En esta tesis se realiza, en primer lugar, un estudio completo del fen��meno f��sico del intercambio de calor entre el medio ambiente y el cuerpo de la presa, estableciendo el mecanismo de participaci��n de todos los par��metros que configuran el problema. En segundo lugar se realiza a cabo una revisi��n documental detallada de los m��todos y t��cnicas utilizables tanto en la estimaci��n de las cargas t��rmicas ambientales como en la evaluaci��n de las tensiones inducidas por dichas cargas. En tercer lugar se establecen rangos de variaci��n para los principales par��metros que configuran el problema. Los par��metros geom��tricos de la presa se definen a partir de la descripci��n de un amplio conjunto de presas arco-gravedad tanto espa��olas como del resto del mundo. Como referencia pr��ctica de los par��metros que definen la acci��n t��rmica ambiental se establecen en Espa��a un conjunto de zonas caracterizadas por que, en cada una de ellas, los par��metros t��rmicos alcanzan valores homog��neos. As��, y en base a series de valores hist��ricos, se establecen la media y la amplitud de la variaci��n anual de la temperatura ambiental en cada una de las zonas. Igualmente, se han definido para cada zona los incrementos de temperatura que, en invierno y en verano, produce la insolaci��n. En relaci��n con el agua del embalse y en la hip��tesis de estratificaci��n t��rmica de este, se han definido los valores, aplicables en cada una de las zonas, de las temperaturas m��xima y m��nima en el fondo as�� como la ley de variaci��n de la temperatura con la profundidad. Utilizando modelos tridimensionales de elementos finitos se analizan diferentes configuraciones de la presa y la cimentaci��n sometidas, cada una de ellas, a diferentes combinaciones de carga. Aplicando t��cnicas num��ricas a modelos unidimensionales se analiza el comportamiento t��rmico temporal de secciones de espesor variable. Considerando conjuntamente los resultados de los an��lisis anteriores se obtienen conclusiones parametrizadas de detalle sobre la influencia que tiene en el estado tensional de la estructura la consideraci��n de la acci��n t��rmica ambiental.

Testing a GIS-based methodology for optimal location of Pumped Storage power plants in Norway

Europe needs to restructure its energy system. The aim to decrease the reliance on fossil fuels to a higher dependence on renewable energy has now been imposed by The European Commission. In order to achieve this goal there is a great interest in Norway to become "The Green Battery of Europe". In the pursuit of this goal a GIS-tool was created to investigate the pump storage potential in Norway. The tool searches for possible connections between existing reservoirs and dams with the criteria selected by the user. The aim of this thesis was to test the tool and see if the results suggested were plausible, develop a cost calculation method for the PSH lines, and make suggestions for further development of the tool. During the process the tool presented many non-feasible pumped storage hydropower (PSH) connections. The area of Telemark was chosen for the more detailed study. The results were discussed and some improvements were suggested for further development of the tool. Also a sensitivity test was done to see which of the parameters set by the user are the most relevant for the PSH connection suggestion. From a range of the most promising PSH plants suggested by the tool, the one between Songavatn and Totak was chosen for a case study, where there already exists a power plant between both reservoirs. A new Pumped Storage Plant was designed with a power production of 1200 MW. There are still many topics open to discussion, such as how to deal with environmental restrictions, or how to deal with inflows and outflows of the reservoirs from the existing power plants. Consequently the GIS-tool can be a very useful tool to establish the best possible connections between existing reservoirs and dams, but it still needs a deep study and the creation of new parameters for the user.

Analyzing climate change adaptation in the agriculture and water sectors: screening risks and opportunities.

As part of the Mediterranean area, the Guadiana basin in Spain is particularly exposed to increasing water stress due to climate change. Future warmer and drier climate will have negative implications for the sustainability of water resources and irrigation agriculture, the main socio- economic sector in the region. This paper illustrates a systematic analysis of climate change impacts and adaptation in the Guadiana basin based on a two-stage modeling approach. First, an integrated hydro-economic modeling framework was used to simulate the potential effects of regional climate change scenarios for the period 2000-2069. Second, a participatory multi-criteria technique, namely the Analytic Hierarchy Process (AHP), was applied to rank potential adaptation measures based on agreed criteria. Results show that, in the middle-long run and under severe climate change, reduced water availability, lower crop yields and increased irrigation demands might lead to water shortages, crop failure, and up to ten percent of income losses to irrigators. AHP results show how private farming adaptation measures, including improving irrigation efficiency and adjusting crop varieties, are preferred to public adaptation measures, such as building new dams. The integrated quantitative and qualitative methodology used in this research can be considered a socially-based valuable tool to support adaptation decision-making.