Characterization of the instability mechanisms affecting slopes on carbonatic Flysch: Alicante (SE Spain), case study

The studied Flysch sequence of Alicante occupies a widely populated area crossed by main communication routes. The slopes existing on this area usually suffer slope instabilities that cause substantial damage and a very high maintenance cost. In order to assess the type of instability mechanisms affecting these heterogeneous carbonatic slopes, in this paper a wide inventory of 194 Flysch rock slopes has been performed, reporting the existing lithologies, their competence and their relative arrangement and the geometrical relationship between bedding and the slope and the associated instability mechanism. All these data have been jointly used for performing an instability mechanisms characterization. For systematically characterizing the wide type of complex rock exposures existing in the study area, they are divided into basic units referred as lithological pattern columns to which the different observed instability mechanisms are associated. Inventoried instability mechanisms are diverse and sometimes are combined with each other. Rockfalls are a very common instability mechanism associated to the differential weathering and sapping of the marly lithologies which are present in a wide number of geometrical combinations. The other instability mechanisms closely depend on the combination of the geometrical and lithological parameters. Therefore, this work provides a new basic tool which can be easily used during preliminary project stages for knowing the instability mechanisms which can affect rock slopes excavated on carbonatic Flysch heterogeneous geological formations.

Monitoring an earthfill dam using differential SAR interferometry: La Pedrera dam, Alicante, Spain

Surface displacement at the dykes of La Pedrera reservoir (SE Spain) has been measured by satellite differential Synthetic Aperture Radar (SAR) interferometry. At the main dyke, a displacement of about 13 cm along the satellite line of sight has been estimated between August 1995 and May 2010, from a dataset composed by ERS-1, ERS-2 and Envisat-ASAR images. Two independent short-term processing tasks were also carried out with ERS-2/Envisat-ASAR (from June 2008 to May 2010) and TerraSAR-X (from August 2008 to June 2010) images which have shown similar spatial and temporal displacement patterns. The joint analysis of historical instrument surveys and DInSAR-derived data has allowed the identification of a long-term deformation process which is reflected at the dam's surface and is also clearly recognizable in the inspection gallery. The plausible causes of the displacements measured by DInSAR are also discussed in the paper. Finally, DInSAR data have been used to compute the long-term settlement of La Pedrera dam, showing a good agreement with external studies. Consequently, this work demonstrates the integration of DInSAR with in-situ techniques which helps provide a complete spatial vision of the displacements in the dam thereby helping to differentiate the causal mechanisms.

Temperature influence on the physical and mechanical properties of a porous rock: San Julian's calcarenite

This work discusses the results from tests which were performed in order to study the effect of high temperatures in the physical and mechanical properties of a calcarenite (San Julian's stone). Samples, previously heated at different temperatures (from 105 °C to 600 °C), were tested. Non-destructive tests (porosity and ultrasonic wave propagation) and destructive tests (uniaxial compressive strength and slake durability test) were performed over available samples. Furthermore, the tests were carried out under different conditions (i.e. air-cooled and water-cooled) in order to study the effect of the fire off method. The results show that uniaxial compressive strength and elastic parameters (i.e. elastic modulus and Poisson's ratio), decrease as the temperature increases for the tested range of temperatures. A reduction of the uniaxial compressive strength up to 35% and 50% is observed in air-cooled and water-cooled samples respectively when the samples are heated to 600 °C. Regarding the Young's modulus, a fall over 75% and 78% in air-cooled and water-cooled samples respectively is observed. Poisson's ratio also declines up to 44% and 68% with the temperature in air-cooled and water-cooled samples respectively. Slake durability index also exhibits a reduction with temperature. Other physical properties, closely related with the mechanical properties of the stone, are porosity, attenuation and propagation velocity of ultrasonic waves in the material. All exhibit considerable changes with temperature.

Influence of using slag cement on the microstructure and durability related properties of cement grouts for micropiles

Today, the use of micropiles for different applications has become very common. In Spain, the cement grouts for micropiles are prepared using ordinary Portland cement and w:c ratio 0.5, although the micropiles standards do not restrict the cement type to use, provided that it reaches a certain compressive strength. In this study, the influence of using slag cement on the microstructure and durability related properties of cement grouts for micropiles have been studied until 90 hardening days, compared to an ordinary Portland cement. Finally, slag cement grouts showed good service properties, better than ordinary Portland cement ones.

Blending of industrial waste from different sources as partial substitution of Portland cement in pastes and mortars

Binary and ternary combinations of sewage sludge ash (SSA) with marble dust (MD), fly ash (FA) and rice husk ash (RHA) as replacement in Portland cement pastes, were assessed. Several tests were carried out at different curing ages: thermogravimetry, density, water absorption, ultrasonic pulse velocity and mechanical strengths. Pozzolanic effects of the mineral admixtures, densities similar to control sample and improved absorptions when combining waste materials were identified. In general, the compressive strength reaches or exceeds the cement strength class, and blending SSA, FA and RHA (30% cement replacement) increase of strength by 9%, compared to the control sample, was achieved.

A quasi-elastic aquifer deformational behavior: Madrid aquifer case study

The purpose of this paper is to analyze the quasi-elastic deformational behavior that has been induced by groundwater withdrawal of the Tertiary detrital aquifer of Madrid (Spain). The spatial and temporal evolution of ground surface displacement was estimated by processing two datasets of radar satellite images (SAR) using Persistent Scatterer Interferometry (PSI). The first SAR dataset was acquired between April 1992 and November 2000 by ERS-1 and ERS-2 satellites, and the second one by the ENVISAT satellite between August 2002 and September 2010. The spatial distribution of PSI measurements reveals that the magnitude of the displacement increases gradually towards the center of the well field area, where approximately 80 mm of maximum cumulated displacement is registered. The correlation analysis made between displacement and piezometric time series provides a correlation coefficient greater than 85% for all the wells. The elastic and inelastic components of measured displacements were separated, observing that the elastic component is, on average, more than 4 times the inelastic component for the studied period. Moreover, the hysteresis loops on the stress–strain plots indicate that the response is in the elastic range. These results demonstrate the quasi-elastic behavior of the aquifer. During the aquifer recovery phase ground surface uplift almost recovers from the subsidence experienced during the preceding extraction phase. Taking into account this unique aquifer system, a one dimensional elastic model was calibrated in the period 1997–2000. Subsequently, the model was used to predict the ground surface movements during the period 1992–2010. Modeled displacements were validated with PSI displacement measurements, exhibiting an error of 13% on average, related with the inelastic component of deformation occurring as a long-term trend in low permeability fine-grained units. This result further demonstrates the quasi-elastic deformational behavior of this unique aquifer system.

Implementación de metodologías docentes interactivas basadas en las nuevas tecnologías en Ingeniería del Terreno

Las asignaturas que se imparten desde el área de conocimiento de Ingeniería del Terreno del Departamento de Ingeniería Civil de la Universidad de Alicante tienen una componente práctica muy importante. Sin embargo, los alumnos, tras finalizar la práctica presencial no disponen de un soporte físico que les permita reproducir lo realmente plasmado durante su desarrollo. Con el fin de subsanar esta deficiencia, durante los últimos tres años, desde nuestro ámbito de conocimiento, hemos venido implementando una serie de mejoras en la metodología docente relacionadas con las nuevas tecnologías. Ello ha permitido que el alumnado pueda reproducir algunas prácticas de laboratorio de forma deslocalizada (tanto en el tiempo como en el espacio), a través de la conexión a los sitios web implementados a tal efecto. Sin embargo, algunas prácticas, tales como las de reconocimiento de materiales pétreos o incluso las de campo, no se adaptan bien a la metodología anteriormente citada. Es por ello, que en este trabajo se plantea implementar una nueva propuesta metodológica, más interactiva, exportable fácilmente incluso a las prácticas de campo. La tecnología elegida está basada en los códigos QR, Quick response Code, recurriéndose a ella tras la constatación de que el alumnado actual es un usuario asiduo de los dispositivos móviles.

Empleo de drones (RPAS) para la elaboración de material audiovisual docente en asignaturas de Ingeniería Civil

El presente trabajo estudia la utilización de drones telecomandados de uso comercial (RPAS) para producir material audiovisual específico de diversas asignaturas de las titulaciones de Ingeniería Civil. Se trata de un equipamiento de alta tecnología y coste relativamente asequible, en torno a 1.300 euros, para producir material audiovisual que hasta ahora únicamente podría ser obtenido empleando medios mucho más limitados (fotografías aéreas y de satélite) o mucho más costosos, tales como vuelos fotográficos específicos. De este modo, se valorará la viabilidad de introducción de una nueva herramienta tecnológica de innovación educativa hasta ahora no empleada en la elaboración de material docente, analizando sus principales ventajas y limitaciones.

Empleo de las nuevas tecnologías y de las redes sociales en asignaturas fuertemente conceptuales

En asignaturas fuertemente conceptuales, como la Mecánica del Suelo y de las Rocas, el alumno no es consciente de ello hasta que se decide a estudiar para poder superar una prueba parcial. Para entonces es demasiado tarde, razón por la cual se produce un elevado índice de fracasos en esta materia integrada en el Grado en Ingeniería Civil. Aprovechando que el alumnado actual es un usuario asiduo de los dispositivos móviles, mediante el empleo de las redes sociales, concretamente Twitter, se envía regularmente, casi a diario, tweets con “píndoles geotècniques” (píldoras geotécnicas en castellano) muy conceptuales y reducidas, con el fin de que el alumno, sin darse cuenta, asuma los conceptos más importantes de la asignatura. Al mismo tiempo, en muchos tweets se le redirige a una página web (El tauler geotècnic o el Tablón geotécnico en castellano) creada ex proceso para la asignatura, donde la información se amplía con material de apoyo mayoritariamente audiovisual, que es mejor asimilado por parte del alumnado. Además este sitio web dispone de pruebas de autoevaluación, enlaces con otras webs del ámbito de la Ingeniería del terreno, con información adicional, aplicaciones informáticas desarrolladas por los profesores del área o de libre acceso, etc.

Herramientas de aprendizaje de mecánica de suelos

La Mecánica de Suelos constituye una disciplina fundamental en las enseñanzas técnicas de Ingeniería Civil. Las asignaturas en las que se imparte Mecánica de Suelos tienen una importante carga conceptual que, en ocasiones, requiere largos procesos de aprendizaje para ser asimilada por el alumnado. La combinación de las clases teóricas con la visualización y realización de sencillos experimentos didácticos de laboratorio facilitan el aprendizaje de dicha materia y la comprensión de los fenómenos complejos de una forma sencilla y amena. En el presente trabajo se describen diversos experimentos que se están desarrollando en el área de Ingeniería del Terreno de la Universidad de Alicante para explicar fenómenos geotécnicos complejos como son el sifonamiento de las arenas, la rotura del fondo de una excavación, la red de flujo de una presa o la carga de hundimiento de una cimentación entre otros. Esta parte experimental es acompañada de todo el desarrollo físico-matemático con el fin de facilitar una comprensión integral del fenómeno.

La formación en la enseñanza actual: nuevos enfoques ante las necesidades cambiantes en nuestra sociedad

El proceso de convergencia europea para la creación de un Espacio Europeo de Educación Superior (EEES) ha originado importantes cambios en la comunidad universitaria. La modificación de los planes de estudio derivadas de dicho proceso de convergencia ha generado nuevas necesidades de infraestructura a las que las universidades han tenido que adaptarse. Por otro lado, los nuevos cambios han proporcionado una oportunidad única para adaptar, con mayor o menor éxito, los nuevos planes de estudio a las necesidades sociales y homogeneizar sus contenidos. Las nuevas titulaciones otorgan un mayor protagonismo al alumno que participa activamente en el proceso de aprendizaje. Asimismo, el profesorado adquiere un nuevo rol, siendo precisamente una de las funciones principales evaluar el proceso de aprendizaje de su alumnado. En este contexto de cambio ya casi finalizado, las Nuevas Tecnologías de la Información y Comunicación (TIC) se han convertido en unas herramientas prácticamente imprescindibles. El presente documento recoge las conclusiones más relevantes de las comunicaciones presentadas en la mesa número 11 de las XI Jornadas de Redes de Investigación en Docencia Universitaria celebradas en la Universidad de Alicante.

Revisiting the effect of foundation embedment on elastic settlement: A new approach

The effect of foundation embedment on settlement calculation is a widely researched topic in which there is no scientific consensus regarding the magnitude of settlement reduction. In this paper, a non-linear three dimensional Finite Element analysis has been performed with the aim of evaluating the aforementioned effect. For this purpose, 1800 models were run considering different variables, such as the depth and dimensions of the foundation and the Young’s modulus and Poisson’s ratio of the soil. The settlements from models with foundations at surface level and at depth were then compared and the relationship between them established. The statistical analysis of this data allowed two new expressions, with a mean maximum error of 1.80%, for the embedment influence factor of a foundation to be proposed and these to be compared with commonly used corrections. The proposed equations were validated by comparing the settlements calculated with the proposed influence factors and the true settlements measured in several real foundations. From the comprehensive study of all modelled cases, an improved approach, when compared to those proposed by other authors, for the calculation of the true elastic settlements of an embedded foundation is proposed.

Brackish groundwater desalination by reverse osmosis in southeastern Spain. Presence of emerging contaminants and potential impacts on soil-aquifer media

Desalinated brackish groundwater is becoming a new source of water supply to comply with growing water demands, especially in (semi-) arid countries. Recent publications show that some chemical compounds may persist in an unaltered form after the desalination processes and that there is an associated risk of mixing waters with different salinity for irrigation. At the university of Alicante campus (Spain), a mix of desalinated brackish groundwater and water from the existing aquifer is currently applied for landscape irrigation. The presence of 209 emerging compounds, surfactants, priority substances according to the 2008/105/EC Directive, 11 heavy metals and microbiological organisms in blended water and aquifer samples was investigated. Thirty-five compounds were detected (pesticides, pharmaceuticals and surfactants) among them two priority substances α-endosulfan and Ni were found above the permitted maximum concentration. Blended water used for landscape irrigation during the summer period is supersaturated with respect to carbonates, which may ultimately lead to mineral precipitation in the soil-aquifer media and changes in hydraulic parameters.

Using Sewage-Sludge Ash as Filler in Bituminous Mixes

In this study, the behavior of bituminous mixes made with sewage sludge ash (SSA) as mineral filler was investigated. The behavior of these mixes was evaluated with the Cantabro, indirect tensile strength, water sensitivity, permanent deformation, and resilient modulus tests. The results show that SSA waste may be used in bituminous mixes at approximately 2–3% weight percent, maintaining adequate levels of cohesion and adhesion in the mixtures, which is comparable to mixtures made with active fillers such as hydrated lime and cement. Moreover, its use does not increase permanent deformations. However, the resilient modulus test gave slightly lower results for mixes made with SSA than for mixtures made with other fillers. It may be concluded that SSA waste may be used as a filler for bituminous mixes with better results than for mixes made with limestone fillers and with similar results for mixes made with other fillers such as hydrated lime and cement.