A laboratory investigation on the cyclic liquefaction resistance of pyroclastic soils

摘要

The paper analyzes the cyclic liquefaction behaviour of a pyroclastic silty sand typical of Neapolitanrnarea through an extensive laboratory investigation. Cyclic undrained stress-controlled triaxial tests on naturalrnand reconstituted samples were addressed to study the influence of state variables, such as relative density andrneffective confining stress, as well as of constitutive factors, i.e. fabric, particle breakage and non-plastic finerncontent. The results highlight that liquefaction resistance of the natural soil is significantly enhanced by fabricrnwith respect to that of reconstituted samples tested at the same state conditions; on the other hand, the cyclicrnstrength of the reconstituted soil appears poorly affected by the relative density and confining stress. Furthermore,rnthe non-plastic fine ash was observed to increase the cyclic resistance of the pumice sand with respect tornthat of the same coarse matrix added with plastic clay. Finally, no appreciable evidences of grain crushing wererndetected on all tested soils containing pumice sand.