Open AccessEARTH RETAINING STRUCTURES THAT ALLOW ROAD INFRASTRUCTURE PROJECTS COASTING A FLYSCHIOID ROCK VALLEY
Author(s) -
A. Mangiola,
G. D. Malgeri,
E. Mittiga
Publication year - 2021
Publication title -
iop conference series. earth and environmental science
Language(s) - English
Resource type - Journals
eISSN - 1755-1307
pISSN - 1755-1315
DOI - 10.1088/1755-1315/833/1/012083
Subject(s) - colluvium , geology , marl , context (archaeology) , sedimentary depositional environment , outwash plain , cohesion (chemistry) , stratigraphy , geomorphology , geotechnical engineering , mining engineering , structural basin , alluvium , glacial period , paleontology , tectonics , chemistry , organic chemistry
This note concerns the main geotechnical features of two road infrastructures, located in northwestern Italy. They are adjoining and situated from km 31+500 to km 35+600 of the national road “Strada Statale n. 45 di Val Trebbia”, along Trebbia river valley, across the Ligurian Apennines. The road, mostly in the half-way section, coasts a valley featured by orographic slopes with an average slope of 25°-30°, which rise up to 1100m above sea level. The stratigraphy, starting from the top level to the deepest, shows: a thin layer of eluvial-colluvial soil; a layer, 3-5m thick, of fractured rock, and underneath the hard marl substrate that belong to the flyschioid formation of Ronco. In this context, to widen the carriageway, improve the design speed of the road section and carry out the works under traffic, a systematic use of earth retaining structures has been conceived. Thanks to the experience taken from the works of the previous project, a more conservative geotechnical characterization has been adopted in the second one. This has meaning for the lithotype called intact rock, in the equivalent Mohr-Coulomb model, a significant reduction in cohesion against a slight increase of friction angle; furthermore, a correspondent variation resulted for the fractured rock.