Effect of compaction on desiccation and consolidation behavior of clay tills

This paper investigates the effect of compaction on the desiccation and consolidation behavior of clay tills. The main contribution of this research is the interpretation of soil properties based on conventional laboratory testing and the development of appropriate mathematical functions to simulate soil behavior during compaction. The soil showed an air entry of 700 kPa (along with an initial low value on dry of optimum) and a residual suction value of 5 × 104 kPa. The swell–shrink curve was s-shaped comprising structural, normal and residual stages on dry of optimum and j-shaped with no structural stage on wet of optimum. The swelling path was also s-shaped comprising initial, primary, and secondary stages. The swelling potential increased on dry of optimum and decreased on wet of optimum with the highest value (3.5%) at the optimum. The Cc on dry of optimum decreased and bounced back on wet of optimum whereas the Cs remained constant (0.045 ± 0.005). Similarly, ks decreased by four orders of magnitude (from 10–8 to 10–12 m/s) with a void ratio decrease from 0.6 to 0.2. A normalized void ratio was defined that correlated test data under the two stress state variables and rendered new constitutive relationships. The WRC fit parameters pertain to initiation and cessation of pore contraction whereas the consolidation fit parameters relate to pre-stress and creep. These sigmoidal equations help construct a conceptual volume change surface to assess various combinations of desiccation and consolidation.