Energy-Based Assessment of the Cyclic Behavior of Sand Stabilized with Colloidal Silica

Colloidal silica (CS) grouting is a soil improvement technique for seismic liquefaction risk mitigation consisting of the injection of a time-hardening, colloidal silica–based grout into potentially liquefiable sandy soils. A published laboratory test database—consisting of cyclic undrained triaxial tests on liquefiable clean untreated sand and on sand stabilized by 5% CS under different levels of initial stress anisotropy—is here discussed following an energy-based approach. The test results are presented and analyzed in terms of dissipated energy during cyclic loading. The obtained results show that (1) the development of dissipated energy is clearly related to the buildup of residual extra pore water pressure only for untreated sand samples; (2) under the same testing conditions, the dissipated energy at failure is significantly higher in stabilized sand than in untreated sand; and (3) the dissipated energy at failure is found to be independent of the cyclic stress amplitude and dependent on the degree of initial stress anisotropy for the untreated sand, while opposite trends are observed for stabilized sand. Therefore, contrary to the untreated sand, there is no evident advantage for using the dissipated energy at failure to assess the capacity of the stabilized sand.