A study of the multi-scale compression behaviour of a sand immersed in a viscous liquid

Pore fluids with different viscosities can exist in soils. While the effects of pore fluids have been investigated at the macro-scale, little is known about how they might affect the micromechanics. A novel apparatus allowing a single particle to be crushed while immersed in a liquid was built here. With the help of a high-speed microscope camera, the crushing processes of single silica sand particles immersed in glycerine were captured and the breakage modes were clarified. The immersion in glycerine leads to stronger particles with higher strains at failure compared with immersion in water or exposure to air. Moreover, the results of constant rate strain oedometer tests revealed that saturation in glycerine made the sample significantly stiffer in compression as a result of less particle breakage compared with that in water or under dry conditions. The lower particle breakage at the macro-scale appeared to correspond to the higher strengths measured at the micro-scale.