A coupled bio-chemo-hydro-wave model and multi-stages for MICP in the seabed

As an environmentally friendly technology, the microbially induced calcite precipitation (MICP) has been gradually applied for the seabed reinforcement. However, there are few models for the simulation of the MICP process in marine environment. A coupled bio-chemo-hydro-wave model for MICP in the seabed was proposed in this paper. This model can capture the bacterial behaviour (growth, decay, attachment, diffusion), the evolutions of chemical substances (urea, calcium, ammonium, calcium carbonate), and the variations of porosity and permeability. It is indicated that (1) distributions of the bacteria and chemical substances show obvious heterogeneity, and are related to the injection rate and injection time; (2) The calcium carbonate content, porosity, and permeability are significantly affected by the initial bacterial concentration, injection rate, injection time and cementing solution concentration. The reduction ratios of porosity and permeability show significant linear increasing trend with the increase of calcium carbonate content; (3) Although MICP process increases the vertical excess pore pressure gradient in the shallow seabed, the seabed can remain stable under the large waves due to the increasing of soil weight and inner cohesive force.