Abstract

Abstract

Abstract
This essay addresses the importance of geotechnics and marine georesources in developing technologies. The study proposes a coastal and marine geoengineering approach that focuses on five domains (5G’s): georesources, geology, geotechnics, geomechanics and geotechnologies. These domains are considered in several engineering projects related to coastal, hydraulic, marine, and maritime applications. The reality of a world in rapid, continuous evolution has put into perspective a multidisciplinary approach combining different practices and coastal strategies. That is the main driving force that should be considered when dealing with geoengineering projects in general. Moreover, geological resources and the potential exploitation of mineral and rock raw materials boost innovative techniques and upscaling geo-robotic systems. Finally, the essay unravels new trends in challenging and extreme environments and natural hazards, highlighting emerging fields such as deep-sea mining, geo-exploration, offshore, coastal, harbour and marine geotechnics. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Abstract

Abstract
This paper is concerned with the effect of sediment accumulation on shore platform development. Boulder accumulations are common on the granitic shore platforms of Galicia, northwestern Spain. Boulders are produced by erosion of shore platforms and of cliffs consisting of cold-climate deposits from the last glacial period. Measurements were made of the long axis length of more than 800 boulders, and additionally of the short and intermediate axes of 340 of these boulders, as well as of their orientation and gradient. There were two study areas. The boulders on the Barbanza Peninsula are generally a little smaller than those in southern Galicia with, respectively; mean long axis lengths of 0.98 and 1.14, and masses of 1.06 and 1.59 t. There are also some isolated, very coarse boulders and megaclasts in southern Galicia. The distribution and extent of the deposits and boulder imbrication and orientation testify to the high levels of wave energy produced by northwesterly and westerly storms in this region. Although the boulders, as well as the underlying shore platforms, were inherited, in part, from previous interglacial stages, some boulder detachment and movement is occurring today during storms, when significant deep water wave heights exceed 8 to 10 m. Despite some abrasion of the shore platforms, the primary effect of large boulder accumulations is protective. The role of sediment on shore platforms has been neglected, but this study suggests that because of arrested development under thick accumulations, platform gradient in areas with abundant sediment increases with the grain size of the material. The occurrence and type of sediment on shore platforms may therefore help to explain the distribution of sloping and subhorizontal platforms under different morphogenic and geological conditions.

Abstract
This work introduces the coastal geo-engineering issues for a suitable selection and geomaterial characterisation of quarries. The development of the research had two main phases: (i) the field survey, applied cartography and inspection of maritime structures and (ii) the geological and geotechnical quarry assessment. This study reports results from the second phase which comprises the evaluation of quarries and the identification of potential areas for the extraction of armourstone with quality and availability to supply maritime structures. It was proposed a zoning of the NW Portugal region and taken into account some features like the land use, urban and settlement plans, geological setting, geotechnical and geomechanical description/typification of the rock masses. 459 quarries were identified, georeferenced and distributed in a total area of 14.010km2. More than 200 sites were selected, characterised and included in the GIS database project with interactive support (e.g. hyperlinks for the datasheets, photos or essential information). A total area of 4,1% was calculated, including relevant geological conditions and comprising existent quarries (active/inactive) or new places (suitable or predictable areas). A multidisciplinary perspective must be adopted providing a cost-effective method useful to the incorporation of important concepts (durability and integrity) in geo-monitoring coastal plans and highlighting GIS coastal projects.