Characterization of soil properties of an earth dam by in situ tests

The paper illustrates experimental techniques and results of the in-situ tests carried out for the mechanical characterization of the Camastra Dam construction materials. SASW, Down Hole (DH) and Dilatometer (DMT) tests were carried out. SASW measurements were performed along three lines in correspondence to the dam crest, the intermediate downstream bank and the dam base. DH and DMT tests were carried out at four verticals along the core axis by adopting a unique device: the Seismic Dilatometer (SDMT). The performed experimental activities can be considered quite innovative for an existing earth dam. All tests were carried out to measure traditional parameters (such as the undrained cohesion), to obtain the shear stiffness dependence with the strain level and, finally, to characterize the distribution of mechanical properties in the core and check its status after about 40 years of dam operation. To properly interpret some test results, knowledge of the stress state within the dam embankment is required. As well known, such a determination is not so trivial in a zoned embankment, where the seepage process takes place. The paper illustrates the procedures followed to obtain the stress state in the dam through numerical approaches. In the conclusions of the paper the effectiveness of each test typology for characterizing the mechanical properties of dam construction materials is elucidated.