Liquefaction of EICP-Treated Sand with Fabric Anisotropy

Fabric anisotropy and cementation can significantly affect the liquefaction behavior of soils. In this study, specimens with different degrees of fabric anisotropy, prepared with air pluviation (AP) and moist tamping (MT) methods, were treated through enzyme-induced carbonate precipitation (EICP). Monotonic and cyclic undrained triaxial tests were performed on the specimens to examine the effects of fabric anisotropy and EICP treatment level on the shear strength and liquefaction resistance. The monotonic test results showed that the peak–state shearing stress ratio of the AP specimens is higher than that of the MT specimens when the EICP treatment cycle is lower than 3. The cyclic test results showed that the untreated AP specimens exhibit lower liquefaction resistance than the untreated MT specimens. For the EICP treatment with a low cementation level, the cyclic undrained strength of the AP specimens increases and becomes even higher than that of the MT specimens. When the treatment level increases, the difference in liquefaction resistance between the AP and MT specimens is reduced due to the decrease of the difference in calcium carbonate content and distribution. In addition, the correlations of the improvement factors with the calcium carbonate content were analyzed. We suggest that the effects of grouting direction and bedding plane direction should be considered when using EICP treatment to mitigate soil liquefaction.