One-phase EICP coupled model and suction assisted grouting for ground improvement

Enzyme induced calcium carbonate precipitation (EICP) is a promising low-carbon alternative for ground improvement. This study develops a coupled model for one-phase EICP suction assisted grouting based on acid-base equilibrium, convection-diffusion-reaction. Results indicate that urease activity is the dominant control on average calcium carbonate content (CCC) and permeability (k/k0). This model is then applied to simulate suction assisted EICP grouting beneath a foundation using two injection strategies. Suction enlarges the Ca2+ plume and the cemented zone, while reducing peak CCC. H6T3 (6 holes and 3 times) produces a wider, moderately cemented region, whereas H3T6 (3 holes and 6 times) forms higher peak CCC near the injection holes but in a narrower band, and suction broadens the low permeability zone. Plate load results show that the ultimate bearing capacity increases from 40.2 kN for the untreated ground to 152 kN at 0 suction and 304 kN at -4 kPa suction for H6T3. Whereas the untreated ground fails in a narrow punching shear zone directly beneath the foundation, the reinforced ground has a 1% CCC contour that acts as a rigid block and transfers the plastic strain band into the uncemented soil.