Simulation of expansion and contraction for sudden plastic flow of Bingham cement grout and Newtonian fluids in a rectangular duct, using the lattice Boltzmann method

Bingham -type fluids are crucial in many industries and in geology. This study examines their behavior in reinforcing fractured rocks. Rheological properties were derived from experimental data of a water -cement mixture. Computational simulations were conducted using Lattice Boltzmann Method, with a modification to the relaxation parameter. Behavior of these mixtures in narrow ducts that widen and narrow suddenly, common in fractured rocks, was analyzed. Comparing Bingham and Newtonian fluids in various duct shapes provided insight into pressure distribution. Findings demonstrate that both cement -water mixtures, with or without addition of cement, adhere to Forchheimer flow patterns. Furthermore, it is observed that Newtonian fluids generate more intense vortices in expansive and contractive areas, resulting in higher pressure drops compared to Bingham plastics. The ultimate goal is to propose a predictive model based on mortar reinforcement for fractured rocks, taking into account rheological properties and watercement ratio, thus reducing the need for costly experiments.