Miguel Cano

Subsidence damage assessment of a Gothic church using differential interferometry and field data

The Santas Justa and Rufina Gothic church (fourteenth century) has suffered several physical, mechanical, chemical, and biochemical types of pathologies along its history: rock alveolization, efflorescence, biological activity, and capillary ascent of groundwater. However, during the last two decades, a new phenomenon has seriously affected the church: ground subsidence caused by aquifer overexploitation. Subsidence is a process that affects the whole Vega Baja of the Segura River basin and consists of gradual sinking in the ground surface caused by soil consolidation due to a pore pressure decrease. This phenomenon has been studied by differential synthetic aperture radar interferometry techniques, which illustrate settlements up to 100 mm for the 1993–2009 period for the whole Orihuela city. Although no differential synthetic aperture radar interferometry information is available for the church due to the loss of interferometric coherence, the spatial analysis of nearby deformation combined with fieldwork has advanced the current understanding on the mechanisms that affect the Santas Justa and Rufina church. These results show the potential interest and the limitations of using this remote sensing technique as a complementary tool for the forensic analysis of building structures.

Assessment of corrective measures for alleviating slope instabilities in carbonatic Flysch formations: Alicante (SE of Spain) case study

As is well known, in order to select remediation measures to correct or prevent slope instabilities, it is essential to identify and characterize the instability mechanisms. This task is especially complex for heterogeneous rock masses such as Flysch formations. This paper addresses the assessment of corrective measures used in carbonate Flysch formations by classifying and grouping field data reported in an available database in order to associate this data with various instability mechanisms and stratigraphic column types as well as with the corrective measures taken to stabilise them. For this purpose, 194 slopes have been geomechanically characterized, mainly by considering the observed instability mechanisms. The corrective measures that were applied have been evaluated for their suitability and performance, and, if applicable, the causes of their malfunction have been also studied. As a result, some guidelines based on the observed behaviour and the suitability of the correction measure as a function of instability type are proposed for similar slopes.RésuméComme il est bien connu, dans le but de sélectionner les mesures correctives pour corriger ou prévenir des instabilités de pente, il est essentiel d’identifier et de caractériser les mécanismes d’instabilité. Cette tâche est d’autant plus complexe pour les masses rocheuses hétérogènes telles que des formations de Flysch. Cet article traite de l’évaluation des mesures correctives utilisées dans les formations du Flysch carbonatée, en classant et groupement des données de terrain figurant dans une base de données disponible, afin d’associer ces données avec les différents mécanismes d’instabilité et les colonnes stratigraphiques type, ainsi que des mesures correctrices prises pour les stabiliser. A cet effet, 194 pentes ont été geomécaniquement caractérisées, principalement en examinant les mécanismes d’instabilité observées. Les mesures correctives qui ont été mis en œuvre ont été évaluées pour leur pertinence, la performance et, le cas échéant, les causes de leur dysfonctionnement. En conséquence, certaines lignes directrices fondées sur le comportement observé et l’adéquation de la mesure de correction en fonction du type de l’instabilité sont proposées pour des pentes similaires.

Using open-source software for extracting geomechanical parameters of a rock mass from 3D point clouds: Discontinuity set extractor and SMRTool

Presentacion de Riquelme et al del Workshop M3EF3, celebrado el 16 y 17 de noviembre de 2017 en la Universidad de Alicante.

A multidisciplinary approach for the investigation of a rock spreading on an urban slope

Landslides are very complex processes controlled by multiple factors. The knowledge and characterization of these factors is essential for a comprehensive understanding of the mechanisms and kinematics of the instabilities and for an efficient design of corrective measures. The aim of this work is to combine traditional geological and geotechnical techniques with geophysical, remote sensing and forensic techniques for obtaining a whole picture of an active lateral spreading affecting the Finestrat municipality in Alicante, SE Spain. Geomorphological, geotechnical and geophysical techniques (i.e. ground penetrating radar and refraction seismic) have provided essential information about the geometry, structure and petro-physical properties of the slope. A Terrestrial Laser Scanner was used for recognizing the most important sets of discontinuities affecting the rock mass and to evaluate the activity of the landslide slope. Complementarily, a forensic analysis of the building damage completed the available datasets, yielding very useful kinematic information of the landslide. Finally, a sensitivity analysis of the stability of the rock slope has been performed considering both block toppling and block sliding models. Therefore, the multisource analysis performed in this work has allowed the identification and characterization of a complex lateral spreading, highlighting its effectiveness for a comprehensive understanding of this type of landslide.

Automatic Mapping of Discontinuity Persistence on Rock Masses Using 3D Point Clouds

Finding new ways to quantify discontinuity persistence values in rock masses in an automatic or semi-automatic manner is a considerable challenge, as an alternative to the use of traditional methods based on measuring patches or traces with tapes. Remote sensing techniques potentially provide new ways of analysing visible data from the rock mass. This work presents a methodology for the automatic mapping of discontinuity persistence on rock masses, using 3D point clouds. The method proposed herein starts by clustering points that belong to patches of a given discontinuity. Coplanar clusters are then merged into a single group of points. Persistence is measured in the directions of the dip and strike for each coplanar set of points, resulting in the extraction of the length of the maximum chord and the area of the convex hull. The proposed approach is implemented in a graphic interface with open source software. Three case studies are utilized to illustrate the methodology: (1) small-scale laboratory setup consisting of a regular distribution of cubes with similar dimensions, (2) more complex geometry consisting of a real rock mass surface in an excavated cavern and (3) slope with persistent sub-vertical discontinuities. Results presented good agreement with field measurements, validating the methodology. Complexities and difficulties related to the method (e.g., natural discontinuity waviness) are reported and discussed. An assessment on the applicability of the method to the 3D point cloud is also presented. Utilization of remote sensing data for a more objective characterization of the persistence of planar discontinuities affecting rock masses is highlighted herein.

Influence of Maritime Construction within Protected Archaeological Sites along Coastal Areas: Los Baños De La Reina (Alicante), Spain

ABSTRACT Aragonés, L.; Tomás, R.; Cano, M.; Rosillo, E., and López, I., 2017. Influence of maritime construction within protected archaeological sites along coastal areas: Los Baños De La Reina (Alicante), Spain. A multidisciplinary study was made assessing the impact of the construction of a harbour on an existing Roman fish farm, which was excavated in the first century BC and placed in Alicante, on the SE coast of Spain. The effect of the harbour on the wave frequencies and the velocity of the streams has been modelled for the different building stages, using the SMC (Sistema de Modelado Costero) software, including consideration of the local maritime climate and bathymetry. The results show that the predominant wave frequencies and the stream velocities increased considerably after harbour construction and, as a result, created new turbulence areas within the influence area of the Roman fish farm. The presence of hydrodynamic bioindicators confirms this result. The lithological structure of the rock mass from which the pools were excavated clearly favours the differential erosion and the subsequent failure of the area, which is now exposed to the impact of ocean waves. The activity of some lithophaga organisms can also increase the degradation of the rock mass. Consequently, a joint analysis of the geological, biological, and maritime information available suggests the degradation of the Roman fish farm located in this area was strongly exacerbated by the construction of the harbour.

Deformational behaviours of alluvial units detected by advanced radar interferometry in the Vega Media of the Segura River, southeast Spain

Abstract It is widely known that differential land subsidence in a valley significantly controls its fluvial dynamics. Nevertheless, major uncertainty exists about the way in which alluvial forms respond to this process. In this study, morphological and lithostratigraphic data have been combined with advanced differential interferometry (A‐DInSAR) to detect changes in alluvial landform elevations and to verify the existence of a differential subsidence pattern influenced by active sedimentary dynamics. For this purpose, the middle reach of the Segura River valley (Vega Media of the Segura River), in southeast Spain, was chosen as the study area. The Vega Media of the Segura River is an alluvial area affected by subsidence processes in close conjunction with depositional conditions, ground‐water withdrawals and faults. A high scale mapping of the main younger sedimentary units was carried out by combining multi‐temporal aerial photographs, high‐resolution digital elevation models derived from LIDAR data, global navigation satellite system data and fieldwork. In addition, lithostratigraphic descriptions were obtained from geotechnical drilling and trenching. Finally, ground surface displacements, measured using A‐DInSAR for the periods 1995–2005 and 2004–2008, allowed the determination of elevation rates and ground deformation associated with the different alluvial units. The results from this analysis revealed four typical deformational behaviours: non‐deformational units (cemented alluvial fans and upper fluvial terraces); slightly deformable units (lower terraces and old abandoned meanders); moderately deformable units (lateral accretion zones and abandoned meanders before channelisation in 1981); and highly deformable areas (recently active meanders associated with artificial cutoffs by channelisation, non‐active floodplains and spilling zones).