Prediction of Cyclic Pore Pressure Build-Up in Pyroclastic Deposits Through a Novel Physically Based Model

Pyroclastic soils cover large areas of the world and, due to their good mechanical properties, are often involved in urban settlements and infrastructures. However, in some cases, they exhibit undrained instability, which has been recog-nized as a major cause of large and rapid flow-like landslides, as well as of large set-tlements due to earthquakes, that catastrophically affect the exposed communities. Although many models have been proposed for predicting the undrained response of sandy deposits, this task remains challenging due to the peculiar properties of pyroclastic soils. To this aim, the behaviour of some deposits of pyroclastic nature under both monotonic and cyclic loadings has been investigated through a wide laboratory experimentation, and a novel physically-based model for pore pressure build-up prediction has been formulated. The model has the great advantage of relying on a few parameters of clear physical meaning and simple experimental determination. Moreover, a range of variation of the parameters governing the undrained response is given, which can be used as a first indication for evaluating soil behaviour in class A predictions. Increasing the reliability of the undrained behaviour prediction under both monotonic and cyclic conditions will lead to a more resilient society, able to prevent or mitigate the associated risks.