Seguimiento geométrico de terraplenes mediante líneas continuas de asiento en la Vega Baja del Segura, Alicante

La Vega Baja del Segura (Alicante) se caracteriza por la baja resistencia portante de los suelos y en consecuencia por las grandes deformaciones que sufren las construcciones que sobre ellos se levantan. La gran demanda turística de vías de comunicación con la costa sur de la provincia de Alicante ha obligado a construir diversas carreteras cuyos terraplenes alcanzan alturas superiores a los 8 m, así como deformaciones decimétricas y en algunos casos excepcionales de magnitud métrica. Las líneas continuas de asiento es una técnica innovadora que se lleva utilizando durante algunos años en la Vega Baja y que evita los laboriosos procedimientos de auscultación topográfica, sirviendo de instrumento de seguimiento geométrico de los mismos y permitiendo la representación gráfica del terraplén original y de su deformada. Esta técnica permite además a la Administración establecer los volúmenes de tierra necesarios para compensar el hundimiento de los terraplenes de forma exacta. Con el presente trabajo se pretende dar a conocer la metodología de las líneas continuas de asientos, así como mostrar algún ejemplo real de aplicación de las mismas, mostrando la evolución geométrica del terraplén en el tiempo y mostrando el procedimiento de cálculo de volúmenes.

Subsidencia del terreno

La subsidencia del terreno es un riesgo natural que afecta a amplias zonas del territorio causando importantes daños económicos y una gran alarma social. La subsidencia del terreno puede deberse a numerosas causas como la disolución de materiales profundos, la construcción de obras subterráneas o de galerías mineras, la erosión del terreno en profundidad, el flujo lateral del suelo, la compactación de los materiales que constituyen el terreno o la actividad tectónica. Todas estas causas se manifiestan en la superficie del terreno mediante deformaciones verticales que pueden variar desde pocos milímetros hasta varios metros durante periodos que varían desde minutos hasta años.

Técnicas de Ingeniería Cartográfica empleadas en el estudio de subsidencia y movimientos de ladera: principales características y análisis comparativo

Los movimientos de ladera y los procesos de subsidencia son fenómenos que afectan a la superficie terrestre produciendo modificaciones importantes sobre ella. Los cambios que originan se manifiestan como deformaciones superficiales cuyo estudio resulta de gran importancia en el campo de la Ingeniería Geología y la Geotecnia. En el presente trabajo se lleva a cabo una descripción de las técnicas de Ingeniería Cartográfica (técnicas topográficas, geodésicas, fotogramétricas y de teledetección) empleadas para cuantificar las deformaciones causadas por movimientos de ladera y subsidencia terrestre, estableciendo sus principales características y llevando a cabo un análisis comparativo de las mismas.

Esquema de anotación para categorización de citas en bibliografía científica

El análisis de citas bibliográficas que usa variaciones de métodos de conteo provoca deformaciones en la evaluación del impacto. Para enriquecer el cálculo de los factores de impacto se necesita entender el tipo de influencia de los aportes de un investigador sobre el autor que los menciona. Para ello, se requiere realizar análisis de contenido del contexto de las citas que permita obtener su función, polaridad e influencia. El presente artículo trata sobre la definición de un esquema de anotación tendiente a la creación de un corpus de acceso público que sea la base de trabajo colaborativo en este campo, con miras al desarrollo de sistemas que permitan llevar adelante tareas de análisis de contenido con el objetivo planteado.

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.

Regional subsidence modelling in Murcia city (SE Spain) using 1-D vertical finite element analysis and 2-D interpolation of ground surface displacements

Subsidence is a hazard that may have natural or anthropogenic origin causing important economic losses. The area of Murcia city (SE Spain) has been affected by subsidence due to groundwater overexploitation since the year 1992. The main observed historical piezometric level declines occurred in the periods 1982–1984, 1992–1995 and 2004–2008 and showed a close correlation with the temporal evolution of ground displacements. Since 2008, the pressure recovery in the aquifer has led to an uplift of the ground surface that has been detected by the extensometers. In the present work an elastic hydro-mechanical finite element code has been used to compute the subsidence time series for 24 geotechnical boreholes, prescribing the measured groundwater table evolution. The achieved results have been compared with the displacements estimated through an advanced DInSAR technique and measured by the extensometers. These spatio-temporal comparisons have showed that, in spite of the limited geomechanical data available, the model has turned out to satisfactorily reproduce the subsidence phenomenon affecting Murcia City. The model will allow the prediction of future induced deformations and the consequences of any piezometric level variation in the study area.

Targetless image-based method for measuring displacements and strains on concrete surfaces with a consumer camera

Measurement of concrete strain through non-invasive methods is of great importance in civil engineering and structural analysis. Traditional methods use laser speckle and high quality cameras that may result too expensive for many applications. Here we present a method for measuring concrete deformations with a standard reflex camera and image processing for tracking objects in the concretes surface. Two different approaches are presented here. In the first one, on-purpose objects are drawn on the surface, while on the second one we track small defects on the surface due to air bubbles in the hardening process. The method has been tested on a concrete sample under several loading/unloading cycles. A stop-motion sequence of the process has been captured and analyzed. Results have been successfully compared with the values given by a strain gauge. Accuracy of our methods in tracking objects is below 8 μm, in the order of more expensive commercial devices.

Stress Inversion Using LiDAR Tunnel Deformation Measurements

Far-field stresses are those present in a volume of rock prior to excavations being created. Estimates of the orientation and magnitude of far-field stresses, often used in mine design, are generally obtained by single-point measurements of stress, or large-scale, regional trends. Point measurements can be a poor representation of far-field stresses as a result of excavation-induced stresses and geological structures. For these reasons, far-field stress estimates can be associated with high levels of uncertainty. The purpose of this thesis is to investigate the practical feasibility, applications, and limitations of calibrating far-field stress estimates through tunnel deformation measurements captured using LiDAR imaging. A method that estimates the orientation and magnitude of excavation-induced principal stress changes through back-analysis of deformation measurements from LiDAR imaged tunnels was developed and tested using synthetic data. If excavation-induced stress change orientations and magnitudes can be accurately estimated, they can be used in the calibration of far-field stress input to numerical models. LiDAR point clouds have been proven to have a number of underground applications, thus it is desired to explore their use in numerical model calibration. The back-analysis method is founded on the superposition of stresses and requires a two-dimensional numerical model of the deforming tunnel. Principal stress changes of known orientation and magnitude are applied to the model to create calibration curves. Estimation can then be performed by minimizing squared differences between the measured tunnel and sets of calibration curve deformations. In addition to the back-analysis estimation method, a procedure consisting of previously existing techniques to measure tunnel deformation using LiDAR imaging was documented. Under ideal conditions, the back-analysis method estimated principal stress change orientations within ±5° and magnitudes within ±2 MPa. Results were comparable for four different tunnel profile shapes. Preliminary testing using plastic deformation, a rough tunnel profile, and profile occlusions suggests that the method can work under more realistic conditions. The results from this thesis set the groundwork for the continued development of a new, inexpensive, and efficient far-field stress estimate calibration method.

Composition of rocks and minerals from the Mid-Atlantic Ridge 5-7°N

The monograph summarizes geological and metallogenic data on the Mid-Atlantic Ridge obtained during research expeditions of the Geological Institute RAS in 2000-2003. Formation of the earth crust in the region, structure of the rift zone, structure of the newly discovered Bogdanov Fracture Zone, neotectonic deformations, metallogenic peculiarities, prospecting criteria of ocean ore mineralization are under consideration.

AMS 14C and calibrated ages of sediment core GeoB10426-1

Newly acquired bathymetric and seismic reflection data have revealed mass-transport deposits (MTDs) on the northeastern Cretan margin in the active Hellenic subduction zone. These include a stack of two submarine landslides within the Malia Basin with a total volume of approximately 4.6 km**3 covering an area of about 135 km**2. These two MTDs have different geometry, internal deformations and transport structures. The older and stratigraphic lower MTD is interpreted as a debrite that fills a large part of the Malia Basin, while the second, younger MTD, with an age of at least 12.6 cal. ka B.P., indicate a thick, lens-shaped, partially translational landslide. This MTD comprises multiple slide masses with internal structure varying from highly deformed to nearly undeformed. The reconstructed source area of the older MTD is located in the westernmost Malia Basin. The source area of the younger MTD is identified in multiple headwalls at the slope-basin-transition in 450 m water depth. Numerous faults with an orientation almost parallel to the southwest-northeast-trending basin axis occur along the northern and southern boundaries of the Malia Basin and have caused a partial steepening of the slope-basin-transition. The possible triggers for slope failure and mass-wasting include (i) seismicity and (ii) movement of the uplifting island of Crete from neotectonics of the Hellenic subduction zone, and (iii) slip of clay-mineral-rich or ash-bearing layers during fluid involvement.

Behavior of one-way slabs reinforced with deformed wire and deformed wire fabric /

Mode of access: Internet.

Structural Insights into Viral Membrane Fusion Machinery via Cryo-Electron Tomography: Influenza Virus and Human Parainfluenza Virus

Thesis (Ph.D.)--University of Washington, 2016-06

On the possibility of elastic strain localisation in a fault

The phenomenon of strain localisation is often observed in shear deformation of particulate materials, e.g., fault gouge. This phenomenon is usually attributed to special types of plastic behaviour of the material (e.g., strain softening or mismatch between dilatancy and pressure sensitivity or both). Observations of strain localisation in situ or in experiments are usually based on displacement measurements and subsequent computation of the displacement gradient. While in conventional continua the symmetric part of the displacement gradient is equal to the strain, it is no longer the case in the more realistic descriptions within the framework of generalised continua. In such models the rotations of the gouge particles are considered as independent degrees of freedom the values of which usually differ from the rotation of an infinitesimal volume element of the continuum, the latter being described for infinitesimal deformations by the non-symmetric part of the displacement gradient. As a model for gouge material we propose a continuum description for an assembly of spherical particles of equal radius in which the particle rotation is treated as an independent degree of freedom. Based on this model we consider simple shear deformations of the fault gouge. We show that there exist values of the model parameters for which the displacement gradient exhibits a pronounced localisation at the mid-layers of the fault, even in the absence of inelasticity. Inelastic effects are neglected in order to highlight the role of the independent rotations and the associated additional parameters. The localisation-like behaviour occurs if (a) the particle rotations on the boundary of the shear layer are constrained (this type of boundary condition does not exist in a standard continuum) and (b) the contact moment-or bending stiffness is much smaller than the product of the effective shear modulus of the granulate and the square of the width of the gouge layer. It should be noted however that the virtual work functional is positive definite over the range of physically meaningful parameters (here: contact stiffnesses, solid volume fraction and coordination number) so that strictly speaking we are not dealing with a material instability.

The Bazhanov-Stroganov model from 3D approach

We apply a three-dimensional approach to describe a new parametrization of the L-operators for the two-dimensional Bazhanov-Stroganov (BS) integrable spin model related to the chiral Potts model. This parametrization is based on the solution of the associated classical discrete integrable system. Using a three-dimensional vertex satisfying a modified tetrahedron equation, we construct an operator which generalizes the BS quantum intertwining matrix S. This operator describes the isospectral deformations of the integrable BS model.