Abstract: With the Q₂^eol loess in Xi’an as research object, the influence of the content of moderately-soluble salt represented by CaSO₄ on the structural strength of undisturbed loess was explored by means of laboratory test and model establishment. Triaxial consolidated undrained shear test was conducted on loess specimens saturated with CaSO₄ solutions of different concentrations(0,0.476,0.952,1.904 g/L) under varying confining pressures(50, 100,200, 400 kPa). The change rules of structural strength of loess were measured and analyzed. Results suggest that the stress-strain curves of the soil specimens displayed hardening features. Under the same confining pressure, the loess strength augmented rapidly and then slowed down along with the increase of soluble salt content. In addition, based on the binary medium model of rock and soil mass,the strength criterion of structural soil mass was modified to obtain the shear resistance sharing rate related to the content of moderately-soluble salt,and the strength criterion of structural loess in consideration of moderately-soluble salt content suitable for Xi’an was established.

Key words: structural loess, content of moderately-soluble salt, geo-binary medium model, shear resistance sharing ratio, strength criterion