New actions and land uses in the historical heritage: the case study of one of the oldest underground water tanks in Madrid (Spain)

The preservation of architectural heritage in Europe is generally associated with the recovery of monumental buildings such as churches and castles, leaving behind a high amount of other historical constructions of civil and industrial architecture that exist in an old country like Spain. High efforts have been devoted by professionals from very different fields aiming to recover and enhance engineering works such as bridges, but the particular case of hydraulic works deserves special attention because it has remained hidden for centuries and sometimes continues to be ignored by society and many institutions. This type of architectural heritage, in the form of underground deposits that represents the case under study in this research, occupies a large area in cities such as Madrid and must be preserved to relieve the pressures of adapting them to accommodate other uses of the land that they occupy. In this paper, the complexity of material characterization and calculation of the Mayor water tank in Madrid (Spain), as an example of this type of construction, is presented. This reservoir currently supplies drinking water to a large part of the city and can accommodate a park on its surface without altering an original 150-year-old structure. As the main conclusion of this research, and in the absence of detailed studies of pathologies, tests, characterization of materials and the terrain, it is recommended to avoid loads greater than 30 kN/m2 in the existing structure, hence the current stresses are not substantially exceeded. This is a recommendation to preserve the historical heritage of this structure against economic and political perspectives that push for a substantial change in its use. This research is an example that can easily be extrapolated to other similar historical infrastructures aiming to guarantee their prevalence in the future

Numerical study on the effects of scour on monopile foundations for Offshore Wind Turbines: The case of Robin Rigg wind farm

Scour around monopiles supporting Offshore Wind Turbines (OWT) may cause a significant reduction in the foundation capacity and the natural frequencies of the soil–structure system. The decommission of two monopiles at the Robin Rigg wind farm after only six years of operation due to massive unexpected scour demonstrates the hazard that an active marine environment poses to OWT. Assessing and predicting the quantitative impact of scour on monopile foundations from a point of view of the utilisation of the foundation capacity is hence crucial to its long-term structural and operational safety. Using finite element analysis, the present study quantifies the influence of scour through moment and lateral load ( ) interaction curves and Load Utilisation (LU) ratios. It analyses the first and second natural frequencies of OWT exposed to different scour morphologies. This methodology is applied to a large-diameter monopile embedded in sand and to the scour-induced failed foundation of the Robin Rigg wind farm. The results indicate that, with increasing scour depth, the capacity and the natural frequencies are reduced due to the loss of lateral confinement. The response of the system is found to depend on the rigidity of the pile governed by the slenderness ratio, the capacity of the soil to redistribute loads with increasing scour, and the effects of overburden pressure on deeper unscoured soil layers. The LU methodology has proven to be an appropriate and efficient approach to predict the long-term performance of scoured monopiles

Uso de modelos uni- y bidimensionales en llanuras de inundación. Aplicación al caso del río Tajo en Talavera de la Reina

[ES] En este trabajo se presenta la experiencia de uso de un modelo hidráulico unidimensional (Hec- Ras) y uno bidimensional (Feswms) en el estudio de la inundabilidad de Talavera de la Reina por el río Tajo. Se revisan los fundamentos y se analizan las aplicaciones de estos modelos, extrayendo las enseñanzas prácticas de sus virtudes e inconvenientes. La avenida de 1947 en Talavera, que teóricamente superó los 7000 m3/s se analiza con detalle.Este trabajo es un resultado del proyecto FEDER I+D 1FD972110C0201Martin Vide, JP.; López Querol, S.; Martín Moreta, P.; Simarro Grande, G.; Benito Ferrández, G. (2003). Uso de modelos uni- y bidimensionales en llanuras de inundación. Aplicación al caso del río Tajo en Talavera de la Reina. Ingeniería del agua. 10(1):49-58. https://doi.org/10.4995/ia.2003.2576OJS4958101U.S. Army Corps of Engineers, Hydrologic Engineering Center (2001) HEC-RAS. River Analysis System. Hydraulic Reference Manual. Version 3.0U.S. Department of Transportation. Federal Highway Administration. FESWMS-2DS: Finite Element Surface -Water Modelling System: Two - Dimensional Flow in a Horizontal Plane. Users ManualMartín-Vide, J.P (1997) Ingeniería fluvial. Edicions UPC, Barcelona.Martín-Vide, J.P.; Prió, J.M.; Bateman, A. "Backwater effects in arch bridges under free and submerged conditions". Journal of Hydraulic Engineering, ASCE (en revisión, 2002).Maza Alvarez, J.A.; García Flores, M. Transporte de sedimentos. Capítulo 10 del Manual de Ingeniería de Ríos. Instituto de Ingeniería de la UNAM, México 1996

A signal-processing approach to assess viscous-damper absorbing boundary conditions for dry and saturated soils in time domain dynamic problems

Financiación de acceso abierto gracias al acuerdo CRUE-CSIC con Elsevier.For numerical modelling of dynamic problems, absorbing boundary conditions (ABC) are necessary to attenuate reflected waves (’box effect’). Different approaches have been developed for this numerical issue, being the viscous damper (VD-ABC) widely employed. The VD-ABC is not frequency dependent but a total attenuation is never achieved, and hence a tentative enlargement of the computational domain is adopted. Relevant issues on VD-ABC are integrative assessment by a signal processing approach. One and two-phases (dry and saturated soil, respectively) time-domain responses have been considered besides spectral properties and energy content. P-wave velocity has been modified to consider the fluid bulk modulus. ABC affect differently to each variable, being the vertical displacement the less sensible. Higher frequencies present great discrepancies although their energy contribution to the overall signal is not relevant. The results with VD-ABC yield to a feasible reduction of the size of the computational domain, maintaining the required accuracy.Para el modelado numérico de problemas dinámicos, las condiciones de contorno absorbentes (ABC) son necesarias para atenuar las ondas reflejadas ("efecto de caja"). Se han desarrollado diferentes enfoques para este problema numérico, siendo ampliamente utilizado el amortiguador viscoso (VD-ABC). El VD-ABC no depende de la frecuencia, pero nunca se logra una atenuación total y, por lo tanto, se adopta una ampliación tentativa del dominio computacional. Los temas relevantes en VD-ABC son la evaluación integradora mediante un enfoque de procesamiento de señales. Se han considerado las respuestas en el dominio del tiempo de una y dos fases (suelo seco y saturado, respectivamente), además de las propiedades espectrales y el contenido de energía. La velocidad de la onda P se ha modificado para considerar el módulo volumétrico del fluido. ABC afecta de forma diferente a cada variable, siendo el desplazamiento vertical el menos sensible. Las frecuencias más altas presentan grandes discrepancias aunque su aporte energético a la señal global no es relevante. Los resultados con VD-ABC dan como resultado una reducción factible del tamaño del dominio computacional, manteniendo la precisión requerida.The first author wants to thank the financial support provided by the Spanish Ministry of Science and Innovation (scholarship BES-2008-002770) during the very preliminary stage of this research, and the Consejeria de Economia, Ciencia Agenda Digital de la Junta de Extremadura and the European Regional Development Fund of the European Union through the reference grant GR21143, for concluding this research. Fig. 12. Dry problem: spectral coherence for ABC solutions between M1010, M2020 and M3535 respect to M5050.peerReviewe

Effect of class F fly ash on fine sand compaction through soil stabilization

This paper presents the results of an experimental investigation carried out to evaluate the effect of fly ash (FA) on fine sand compaction and its suitability as a material for embankments. The literature review demonstrates the lack of research on stabilization of sandy material using FA. The study is concerned with the role of FA content in stabilized soil physical characteristics. The main aim of this paper is to determine the optimum quantity of FA content for stabilization of this type of soil. This is achieved through particle size distribution and compaction (standard proctor) tests. The sand was stabilized with three proportions of FA (5%, 10% and 15%) and constant cement content of 3% was used as an activator. For better comparison, the sand was also stabilized by 3% cement only so that the effect of FA could be observed more clearly. The results were in line with the literature for other types of soil, i.e. as the % of FA increases, reduction in maximum dry density and higher optimum moisture content were observed

Frequency-Domain Assessment of Integration Schemes for Earthquake Engineering Problems

Although numerical integration is a technique commonly employed in many time-dependent problems, usually its accuracy relied on a time interval small enough. However, taking into account that time integration formulae can be considered to be recursive digital filters, in this research a criterion based on transfer functions has been employed to characterize a wide range of integration algorithms from a frequency approach, both in amplitude and in phase. By adopting Nyquist’s criterion to avoid the aliasing phenomena, a total of seven integration schemes have been reviewed in terms of accuracy and distortion effects on the frequency content of the signal. Some of these schemes are very well-known polynomial approximations with different degrees of interpolation, but others have been especially defined for solving earthquake engineering problems or have been extracted from the digital signal processing methodology. Finally, five examples have been developed to validate this frequency approach and to investigate its influence on practical dynamic problems. This research, focused on earthquake and structural engineering, reveals that numerical integration formulae are clearly frequency-dependent, a conclusion that obviously has a relevant interest in all dynamic engineering problems, even when they are formulated and solved in the time-domain

u–w formulation for dynamic problems in large deformation regime solved through an implicit meshfree scheme

Solving dynamic problems for fluid saturated porous media at large deformation regime is an interesting but complex issue. An implicit time integration scheme is herein developed within the framework of the u–w (solid displacement–relative fluid displacement) formulation for the Biot’s equations. In particular, liquid water saturated porous media is considered and the linearization of the linear momentum equations taking into account all the inertia terms for both solid and fluid phases is for the first time presented. The spatial discretization is carried out through a meshfree method, in which the shape functions are based on the principle of local maximum entropy LME. The current methodology is firstly validated with the dynamic consolidation of a soil column and the plastic shear band formulation of a square domain loaded by a rigid footing. The feasibility of this new numerical approach for solving large deformation dynamic problems is finally demonstrated through the application to an embankment problem subjected to an earthquake

Sorbents for volatile toxic mercury in coal combustion flue gas

Trabajo presentado a la International Conference on Carbon (Carbon'03), celebrada en Oviedo.Peer reviewe