Blast-Induced Liquefaction Results at the Silty-Sand Site of Mirabello, Emilia Romagna Region, Italy

Recent experiences (e.g. New Zealand and United States) show that blast tests can cause liquefaction, inducing undrained cyclic loading, generating excess pore water pressure, and consequently producing real deformations. This paper introduces the results obtained from a research project on blast induced liquefaction, performed at a trial site located in Mirabello (near Ferrara, Italy), a little village strongly affected by liquefaction during the 2012 Emilia-Romagna earthquake. The liquefiable soils in this area contained significantly more fines than in previous blast tests. In particular, the objectives of the experiment were: (i) to evaluate liquefaction induced settlement of Apennine silts and sands, and Po River sands; (ii) to determine downdrag forces on pile foundations; (iii) to measure change in shear wave velocity/shear modulus with excess pore pressure; and (iv) to measure change in soil properties with time after liquefaction. This paper illustrates the results acquired before, during, and after the blast test using in-situ tests, pore pressure transducers, profilometers, topographical surveys, and a test micropile instrumented with strain gauges.