Stress-dependent properties of physicochemical interaction of unsaturated saline clay

To reveal the impact of physicochemical effects on the compressive behaviors of unsaturated clay containing salt solution and its dependence properties on stress level, one-dimensional compression tests are performed on the specimens with pores containing distilled water, sodium chloride solution, sodium sulfate solution and controlled matric suction conditions. Then, the compression index, secondary compression coefficient and yield stress of clay under different conditions are measured according to the test results, and their variation laws with the matric suction and osmotic suction are calibrated. Furthermore, the stress-dependent characteristics of physicochemical action are clarified through an in-depth analysis of the primary and secondary consolidation behaviors of unsaturated saline clay under different matric suctions and osmotic suctions, and the LC yielding behaviors of unsaturated saline clay are explored. The results show that the ratio of the secondary compression coefficient to the compression index ${C_{\text{a}}}/{C_{\text{c}}}$ and the yield stress of unsaturated saline clay at different physicochemical forces can be described uniformly using the osmotic suction and matric suction. From the slope of compression curve in the plastic loading zone and the correlation between characteristic parameter, ${C_{\text{a}}}/{C_{\text{c}}}$ and the vertical stress, it is noted that the physicochemical action of unsaturated saline clay is closely related to the stress level. Moreover, the LC yield curve of unsaturated saline clay is a smooth curve composed of MLC yield curve and OLC yield curve under chemo- hydro-mechanical coupling.