Cyclic behaviour and liquefaction potential of an Italian volcanic soil through the energy-based approach

The energy-based liquefaction evaluation method has recently gained increasing interest, due to its relative independence from the typical factors that affect sandy soils. The normalized cumulative dissipated energy is an important indicator of liquefaction resistance in energy-based models, as it is independent of effective confining stress, stress amplitude, loading type, and test method. As such, this method can be applied more reliably to sands of different natures. Volcanic grains are angular and lightweight, and they may break under cyclic loading, either at the asperities or throughout the entire grain. Current liquefaction evaluation methods, developed for hard-grained sands, are not suitable for these particular soils. Considering that their cyclic behaviour in terms of pore water pressure and strain generation is different from that of hard-grained sands, the aim of this paper is to investigate how grain nature and various influencing factors affect the accumulated dissipated energy in volcanic soils. To evaluate the impact of test type, cyclic triaxial and cyclic simple shear tests were conducted on both undisturbed and reconstituted specimens of an Italian volcanic soil with varying amounts of fines. The role of low-plasticity fines was also examined. Test results showed that fines content, void ratio, and soil fabric influence the relationship between excess pore water pressure development and cumulative dissipated energy. By investigating the key factors that potentially affect the energy-based capacity, this paper provides new insights into the evaluation of the cyclic behaviour of volcanic silty sands.