Influence of the dominant fracture and slurry viscosity on the slurry diffusion law in fractured aquifers

To study the effect of a dominant fracture and slurry viscosity on slurry diffusion in a fracture network, a dynamic water grouting simulation experimental device for fractured rock masses was developed considering factors such as the fracture distribution, water pressure and slurry properties. First, this experimental device was implemented to simulate the slurry diffusion process at three viscosities under three fracture distribution conditions in a confined water fractured rock mass, and the slurry diffusion law was determined. Combined with numerical simulation, the stress distribution and change law in the nine grouting experiments were obtained. Finally, ultrasonic measurements were conducted to analyze the change law of the elastic modulus of the rock mass at the different viscosities after grouting. The results show that (1) the fractured rock mass after transformation exhibits zoning characteristics and can be divided into a fully filled zone (FF zone), a partially filled zone (PF zone), a developed fracture zone (DeF zone), and an original fracture zone (OF zone); (2) the diffusion morphology of the slurry in the fracture field with uniformly distributed fractures resembles a ∩ shape, and the diffusion morphology in the fracture field with a dominant fracture exhibits a Λ shape; (3) with increasing slurry viscosity, the diffusion area gradually decreases, and the stress of the high-viscosity slurry on the fractured rock matrix is higher than that of the low-viscosity slurry on the fractured rock matrix during diffusion; (4) the higher the grouting pressure on the fractured rock matrix is and the longer the time is, the higher the enhanced elastic modulus of the fractured rock matrix is. After modification of the high-viscosity slurry, the average dynamic elastic modulus of the rock matrix increased 96.0%.