This study was carried out to improve diagnosis and prediction of geomaterials status from coastal protection structures. A methodology is proposed for the characterization of rock materials and management of the structures. The characterization was organized in different phases: i) visual inspection; ii) field techniques to study geologic-geotechnical features; iii) in situ measurement of geomechanical parameters; and iv) development of GIS-based mapping and assessment of the block materials. The results obtained allowed to define a geotechnical zonation for the structure armor layer, according to the type of geomaterial source, weathering/degradation grade and geomechanical rebound values. The GIS project developed, combined an applied cartography of the groins' superficial layer with the results of the field techniques. The interactive base included the pilot case presented in this work, from Espinho coastal area (NW Portugal, Iberian Peninsula), which comprises four different sectors. The results of this work, support the need to apply geomechanic concepts to coastal structures, since they allow the evaluation of deterioration levels and improve the planning of intervention works. This methodology contributes to ameliorate the efficiency of monitoring and maintenance, in an economically beneficial mode.

1.1Coastal geoengineering

The coastal human population has been growing in many countries around the world. It is currently estimated that about half of the globe population lives in coastal zones, although there is large variation among countries. In several countries, coasts currently face severe sea-level rise problems as a consequence of tectonic and anthropogenically induced subsidence. Also, historically, many geoscientists and engineers had to deal with natural hazards, like landslides and river and coastal erosion which affect the shoreline. On the other hand, human activities and the development of urban areas, may also affect coastal zones, making this environmental issue one of the most serious problems of the world. From the geoengineering point of view, and in a scientific context, impacts caused by the construction of large structures and incorrect land use require comprehensive geological, geomechanical studies and engineering solutions for their mitigation (Bock, 2006).

During the last decades, the importance of geotechnical and geoengineering matters for rock characterization, together with the need to provide for its development, has been recognized (Manoliu & Radulescu, 2008). The use of GIS (Geographic Information System) databases is nowadays considered a useful tool that provides scientific background to evaluate parameters used as well as the results produced (Burke et al., 2001). In this work, using guidelines and procedures for the evaluation of rocks, it was possible to develop a GIS-based methodology that establishes a bridge between specific geological construction materials (geomaterials) and the design of coastal protection structures.

1.2 The rock project:importanceofgeomaterials characterization/evaluation

The main considerations for a rock project are its scale and the availability, quality and handling of materials (Dupray et al., 2004; Latham et al., 2006a,b). In fact, our ports and coastal defences are vital, among others, to the maintenance of trade and economic development.

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