A critical overview of geophysical investigation and laboratory test results used in the seismic re-evaluation of the Farneto del Principe dam in Italy

This paper describes a comprehensive geotechnical characterization campaign performed on a major zoned earth dam in Southern Italy (the Farneto del Principe dam), by means of field investigation and laboratory test. Results from these tests will be used to perform a seismic re-evaluation of the dam, to comply with the new standards issued by the Italian National Authority for Dams. A series of invasive (cross-hole and down-hole) and non-invasive (multichannel analysis of surface waves, MASW) geophysical tests, in addition to traditional geotechnical field tests, such as cone penetration tests and standard penetration tests were carried out to evaluate geotechnical characteristics of the dam, focusing on shear wave velocity (and shear modulus) profiles of the clay core and the shells. Several cyclic laboratory tests by means of resonant column tests were also performed on undisturbed specimens collected in the clay core of the dam. Such data formed the basis for developing a geotechnical model used to evaluate the seismic response of the dam. As expected, we observe that in the clay core and the shells of the Farneto del Principe dam, the small-strain shear modulus increases with depth following a non-linear trend. Such test results are then compared to existing empirical models. This study aims to provide insights into the geotechnical and geophysical characterization of existing dams. As such, it could be used as a benchmark for planning future field investigation campaign studies.