Document Type : Original Research Paper
Authors
1 University of Kashan
2 Associate Professor , university of kashan
3 university of Kashan
Abstract
The study investigated how time-dependent viscosity affects the penetration length of cement-based grouts prepared with saline and fresh water. An idealized horizontal fracture, represented by two smooth, parallel, and frictionless plates, was assumed. The grout viscosity, varying over time, was analyzed to determine the maximum penetration length under a constant injection period. A fracture model was developed and meshed in Gambit, and the two-phase fluid behavior with time-dependent viscosity was simulated in ANSYS Fluent. One saline water function and two fresh water functions were examined. The saline grout was tested at 1475 and 1625 kg/m³, while the fresh water grouts were analyzed at 1475 kg/m³. The resulting penetration lengths were 1.384 m and 1.789 m for the fresh water grouts, and 0.789 m and 0.427 m for the saline grouts, respectively. The outcomes reveal that saline water grout penetrates less effectively than fresh water grout. Furthermore, the effect of density was found to be minor compared to viscosity variations, though differences between saline and fresh water systems were clearly evident. This study introduces a stable grout formulation without additives, contrasting with previous research that relied on additives and adjustments to the water-to-cement ratio, which led to grout instability over time. Utilizing CFD simulations, this research models a two-phase water-cement mixture with varying densities and viscosities, treated as a non-Newtonian fluid. Furthermore, the viscosity of the grout over time under hydraulic pressure is examined, providing valuable insights into grout behavior under subsurface conditions.
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