Bio-cementation is a promising method for the liquefiable mitigation of loose saturated sands. In the improvement process a bacterium that can be found naturally in soil deposits is fed urea. The bacterium consumes and breaks down the urea to form ammonium and carbonate. In the presence of calcium, calcium carbonate will precipitate at particle contacts and act as a cementitious agent to solidify the deposit. Moreover, bio-cemented sand exhibits more ductile behavior than chemically cemented sand. This is a desirable response from an engineering point of view, since brittle failure is often catastrophic and occurs without warning.
Models that can predict the behavior of bio-cemented sands in the field must be developed. Discrete element method simulations have been shown to reasonably reproduce the behavior of bonded granular material tested in the laboratory. A new approach for modeling bio-cemented sands is presented. Strings of calcite ‘particles’ are used to bond sand grains via glued contact points. The scheme prevents sliding and separation and transmits moment. Bonds break gradually depending on the geometry of the stress transmission through the assembly. During decementation, fragments of calcite are generated, occupy the pore space, and effect the system response. Load