Numerical modelling of the stress-strain responses of clean and laponite-treated Hostun sands

Laponite is a synthetic clay-like nanomaterial, which can be used to enhance the liquefaction resistance of loose sandy soils. This paper simulates the stress-strain responses of clean and laponite-treated Hostun sands using conventional fluid-solid coupling analyses and elastoplastic constitutive models. Two sets of numerical tools are adopted, namely, OpenSees with PM4Sand and Plaxis 2D with UBC3D-PLM, respectively. The capability of the two elastoplastic constitutive models is firstly validated through the modelling of a series of undrained cyclic triaxial tests on clean and laponite-treated Hostun sands with varying confining pressures and relative densities. The numerical models are constructed in 2D axisymmetric conditions. With proper calibrations, both codes can replicate the dynamic behavior of the soil specimens, and the effects of the laponite treatment have been accounted for by special adjustments on the constitutive parameters. Then, the said numerical tools are applied to the simulation at practical engineering scale, numerically reproducing centrifuge tests conducted with both clean and laponite-treated sands. The simulation results showed good agreement with the experimental data, validating the applicability of the numerical methods for complex boundary value problems. The main outcome of this paper is, however, establishing the capability of conventional numerical methods to capture the nuanced differences between clean and laponite-treated sands as well as offering an approach for proper calibrations. Furthermore, it should be noted that while the laboratory specimens in this study were prepared by dry mixing, the practical field application of laponite typically involves permeation grouting. The feasibility and complex spatial distribution of such injection methods necessitate further large-scale field investigations.