Geotechnical Characterization of theLithological Map of Italy

The increasing availability of computational resources and the widespread use of distributed and parallel computing applications, enable the possible application of physically distributed geo-hydrological models at regional and national scales. However, the potential use of these models is constrained by the lack of data on the geotechnical and lithologic characteristics of rocks and materials. In a recent study, Bucci et al. (2022) published a lithological map of Italy at a 1:100k scale with the specific aim of facilitating the modelling of geo-hydrological phenomena. However, the lithologies on the map are not associated with values or ranges of values of the most important geotechnical parameters relevant to slope stability assessment such as: porosity, influencing soil permeability and drainage capacity, and cohesion and angle of friction, which contribute to defining the soil's resistance to erosion.

An ongoing work at CNR-IRPI, is aimed at assessing whether and how many of the lithotypes presented in Bucci et al. map (2022) can be characterized from a geotechnical perspective and with what level of precision. More than 100 articles published in indexed journals were examined, to extract information on cohesion, friction angle, and porosity for more than108 different lithotypes.

Most of the articles report data obtained through laboratory tests, field experiments, or empirical approaches. The minority of the articles, uses bibliographic sources, or provides data obtained in a mixed manner. The values of cohesion, friction angle, and porosity obtained and assigned to different lithological classes reveal, as expected, significant variability. The range of the values can be attributed to various factors, including: (i) assumptions made to assign specific rocks, formations, or soils to the (few) lithological classes present in the 1:100k map; (ii) the diversity of geological conditions in which lithotypes are formed; (iii) methods and approaches in data acquisition, and (iv) the natural variability of material characteristics.

The results will allow to better characterize or subdivide the lithotypes shown in the cartography by Bucci et al. (2022), with the purpose to reduce uncertainty regarding the values of geotechnical parameters that can be used in physics-based slope stability models.

Reference

F. Bucci , M. Santangelo, L. Fongo , M. Alvioli , M. Cardinali, L. Melelli , and I. Marchesini . A new digital lithological map of Italy at the 1 : 100 000 scale for geomechanical modelling. Earth Syst. Sci. Data, 14, 4129–4151, 2022 https://doi.org/10.5194/essd-14-4129-2022