Mechanical dilatancy and contraction effect of contaminated soil solidified by organic solvent

The mix proportion experiment was applied to investigate the mix proportion scheme of organic soil mass curing agent, and the functional mechanism of organic solvent fused with soil mass was analyzed. Under conditions of low confining pressure (90~240kPa) and relative higher confining pressure (600~1200kPa), the consolidated drained triaxial shear test was applied to compare the mechanical dilatancy and contraction effect of undisturbed soil, contaminated soil and consolidated soil, and draw the mechanical volumetric strain characteristic curves. Then the volumetric strain characteristics of dilatancy and contraction behavior and their peak strength change rules of heavy metal contaminated soil, before and after consolidation, were analyzed. According to Pietruszczak’s hardening rule, the two yield surfaces volumetric strain model of heavy metal contaminated soil was established. Results indicate that heavy metal contaminated soil shows dilatancy property under the low confining condition and contraction property under high confining condition, while peak strength decreases obviously. Soil consolidation effectively improves the dilatancy volumetric strain characteristic under low confining condition, contraction volumetric characteristic under medium to high confining condition, and the peak strength increased significantly. This model makes up for the defect that the traditional single yield surface model cannot describe the critical strain state of dilatancy and contraction, and it reasonably reflects the volumetric strain change process of heavy metal contaminated soil.