Mitigation of liquefaction-induced deformation with magnetorheological mechanism of micron-sized magnetite particles for saturated sand

Soil-liquefaction-induced damage has been a major cause of ground failure and led to structural damage in the past earthquake events. With recent shifts in civil engineering to performance-based design methods, the traditional factor-of-safety-based approach to avoid liquefaction initiation may not be economical to control liquefaction-induced deformations directly leading to damage. In this article, a novel approach using the magnetorheological effect of micron-sized magnetite particles in liquefied sand for post-liquefaction stabilization and deformation mitigation is proposed. The mixture of sand and micron-sized magnetite particles, termed as magnetorheological sand, illustrates field-dependent behavior similar to other magnetorheological materials. The magnetorheological effect is illustrated through a sinking cylinder test of saturated magnetorheological sand prepared with 90% F75 silica sand and 10% 30-micron magnetite particles by weight. The magnetic-field-dependent properties of magnetorheological sand are then fit to a numerical model for evaluation as a foundation material. The performance of a five-story structure resting on a layer of soil on rigid rock with soil–structure interaction is evaluated. The numerical simulation results demonstrate that magnetorheological sand is effective in mitigating liquefaction-induced deformation and has the potential to outperform alternative mitigation approaches.