Effects of Carbonate Distribution Inhomogeneity on the Improvement Level of Bio-cemented Sands: A DEM Study

Abstract

Microbially induced carbonate precipitation (MICP) involves bacteria to drive calcite precipitation and naturally cement soils, thereby improving soils performance. Experimental studies have shown that bio-cemented specimen can suffer from severe spatial inhomogeneity of the calcite content, leading to large uncertainty in treatment efficiency prediction. To evaluate the effect of inhomogeneity on the mechanical behaviour of bio-cemented soils, the discrete element method (DEM) is used to model bio-cemented samples with a single carbonate distribution pattern (i.e. either bridging or contact cementing) but different characteristics of inhomogeneity. Both drained triaxial compression and triaxial extension simulations are carried out to evaluate the impact of inhomogeneity along different loading paths. The results indicate that inhomogeneity has different effects on bio-cemented samples depending on the carbonate distribution patterns and the loading path. Specifically, the shear strength in compression of samples exhibiting bridging cementation is largely affected by inhomogeneity, while the effect on shear strength in extension is negligible. On the other hand, samples with contact cementing show limited sensitivity to the variation of inhomogeneity under both triaxial compression and triaxial extension tests.

Effects of carbonate distribution pattern on the mechanical behaviour of bio-cemented sands: A DEM study

“…minerals (DeJong et al, 2010;Lin et al, 2015;Mujah et al, 2017;Wang et al, 2022), precipitation of different polymorphs of calcium carbonate (i.e. vaterite, aragonite or calcite) or of amorphous calcium carbonate (Van Paassen, 2009;Terzis and Laloui, 2019b), and inhomogeneity of the treated samples (Xiao et al, 2021b;Zhang and Dieudonné, 2023). In particular, four typical distribution patterns of bio-treated sands can be identified (Fig.…”