Simulation of seismic response of passively stabilised sand

Abstract

Passive (site) stabilisation is a novel technique for mitigating the risk of seismic liquefaction in the non-cohesive foundation soil of existing structures. It comprises the low-pressure injection (in the soil pores) of colloidal silica grout, a very low-viscosity material that transforms into a firm gel after a well-controlled time. This gelation improves macroscopically the mechanical response of the soil skeleton–pore fluid system. Owing to the lack of a dedicated constitutive model, this paper explores the potential of using existing constitutive models for sands for simulating the cyclic response of sands (passively) stabilised with colloidal silica. Hence, a well-established plasticity model for sands (named NTUA-Sand) is used for the simulation of pertinent element tests and of a dynamic centrifuge test modelling the seismic response of a stabilised sand layer. It is used in coupled analyses either after recalibration for simulating the stabilised sand response or in combination with a reduced pore fluid modulus. The latter numerical approach simulates the seemingly compressible colloidal silica in the soil pores, instead of incompressible water, and successful comparisons of its phenomenological simulations with test data underline its potential for use in practice.