A liquefaction surface to describe liquefaction phenomena in unsaturated sandy soils
The energetic interpretation of liquefaction tests indicates that the behavior of unsaturated
sands can be related to the specific energy spent to liquefaction In this paper, an insight
is proposed on the role played by the two components of such a specific energy: the specific
volumetric energy to liquefaction (Ev,liq) and the specific deviatoric energy to liquefaction (Es,liq).
It is argued that Ev,liq (which is nil in saturated soils) can be considered as a state variable to
quantify the increase of cyclic resistance caused by a reduced degree of saturation, being thus
constant along a given cyclic resistance curve. Es,liq is instead related to a specific value of cyclic
resistance ratio or number of cycles at liquefaction via the value of the volumetric component. In
fact, for saturated tests (Ev,liq=0) Es,liq is constant for a fixed number of cycles at liquefaction (Nliq).
For unsaturated tests, Es,liq increases as Ev,liq increases for a given value of Nliq. The three variables
(Ev,liq, Es,liq and Nliq) define a “liquefaction surface” describing the resistance to liquefaction of