Abstract: The fall cone tests are performed to determine the consistency limits of Guilin silty clay under different pore fluids; and scanning electron microscope(SEM) analytic technique is used to revel the influence of the chemo-mechanical coupling interaction between water and soil under variable water-chemistry conditions on structure properties of silty clay at a micro scale. The results show that the consistency limits of silty clay would be decreased with the increase of concentration of pore fluids. Besides, it has been found that the atterberg limit decrease as the radius of cation decrease and cation valence increase, especially it’s dominated by cation valence at the same concentration. These features of the sility clay behavior can be attributed to the mechanisms of the electric diffuse double layers which would be decreased after the ion concentration and ion valence increased. What’s more, it can be seen that the flocculation among silty clay particles has been facilitated by the chemo-mechanical coupling interaction between water and soil, and it leads to the formation of granulosity and the pores between particles have been extended at a micro-level.

Key words: silty clay, pore fluid, consistency limits, scanning electron microscope(SEM)