Investigating slurry infiltration in a coral reef limestone based on X-ray computed tomography and CFD-DEM numerical simulation

Abstract

Coral reef limestone is a highly fossiliferous and porous sedimentary rock, ubiquitous in continental shelves and deep oceanic zones. To understand the slurry infiltration process from a microscopic perspective, we use X-ray computed tomography (CT) to reconstruct the complex three-dimensional pore structures of a coral reef limestone sample and further perform CFD-DEM simulations to capture the transport behavior of slurry particles passing through the reef limestone skeleton. The simulation results show that the kinetic energy of slurry particles in general follows a linear relationship with the applied pressure differential, which is influenced by the physical characteristics of pore channels. The particle infiltration time is inversely correlated to the pressure differential obeying a power-law function. In addition, statistical analysis of the length and spatial distribution of particle trajectories indicates the dominant role of high-coordination-number pore spaces in slurry suspension infiltration through the reef limestone. Our results have important implications for slurry shield tunneling through coral reef limestone strata.