Geological-evolutionary model of a gravity-induced slope deformation in the carbonate Central Apennines (Italy)

Abstract

This paper discusses the findings from a study conducted on gravity-induced deformationsoccurring along the SW slope of Mount Nuria linking the village of Pendenza (Rieti, Italy) to the area of San Vittorino, in the alluvial plain of the Velino river, where important infrastructures are present. The dominantly carbonate composition of the rocks outcropping along the slope, the occurrence of a main spring fed by a regional karst aquifer and the interaction of gravity-induced deformations with buildings and infrastructures resting on the slope or located at its base make the investigated case extremely interesting and reflective of phenomena that are common in similar geological-hydrogeological conditions. Insights from this case and their use for the construction of a ‘geological-evolutionary model’ shed more light on the complex interactions existing between jointed carbonate rocks, seepage, karst dissolution, genesis of gravity-induced deformations and their evolution in space and time, through the analysis of stress-strain conditions withinthe slope. According to the selected methodologicalapproach, data from detailed geological, geomorphological and geomechanical surveys were integrated with those from laboratory tests and from a complex slope monitoring system. From the results of the study it was possible to: i) refer the investigated phenomena to gravity-induced deformations on the slope scale; ii) build a representative ‘geological-evolutionary model’ and iii) develop an analytical approach to assess the hazard represented by these deformations for local buildings and infrastructures. The identification of different hazard conditions can helpdefine the type and value of possible mitigation efforts. The investigated case also provided inputs for testing new approaches to the geomechanical characterization of rock masses, to the description of their jointing and to the correlation of their main discontinuities with tectonic and gravity-induced elements.