Engineering geological mapping of heterogeneous rock masses in the Northern Apennines: an example from the Parma Valley (Italy)

Most of the geological formations in the Northern Apennines are made up of flysch and tectonic mélanges. A general characterization of the most common rock masses cropping out in the Val Parma is presented in this paper, using the Marinos–Hoek classification based on the Hoek–Brown criterion. Three groups were identified: heterogeneous rock masses essentially controlled by single discontinuities with strengths much lower than the main rock mass (HH); truly heterogeneous rock masses with approximately equal alternations of hard and weak horizons which fail through the weaker materials (TH) and a rock mass in which the majority of the material is weak, tending to soil-like behaviour (WH). A general engineering geological map of the study area is presented, highlighting the spatial distribution of the three different groups.