Numerical investigation of liquefaction mitigation potential with vibroflotation

Abstract

Vibroflotation is one type of ground improvement technique used for liquefaction mitigation in saturated sand. In order to study the feasibility of vibroflotation for liquefaction mitigation, two numerical models were created in the finite element framework. A nonlinear, coupled, hypoplastic u-p formulation was developed to simulate the behaviour of saturated sand. Numerical results were validated against on-field cone penetration test measurements after vibroflotation and centrifuge test simulating seismic site response of saturated sand. Seismic site response of saturated sand before and after vibroflotation was analysed. Saturated loose sand with fines and lower permeability underwent excess pore pressure generation, softening, and possibly liquefaction under seismic loading before vibroflotation. Sands with higher permeability were found to respond better to vibroflotation. The most effective degree of compaction was achieved in dry sands. Vibroflotation of saturated sand with fines ensured improved resistance against liquefaction whereas for coarse sands it led to complete eradication of the liquefaction.