Numerical Study Of Diffusion Capacity Of The Grout In Three-Dimensional Fracture

As tunneling,water conservancy and mining projects are gradually being built deeper underground,the strength of the underground rock mass has a greater impact on the stability of the project.However,due to the presence of a large number of fissures in the rock mass,sudden water accidents can occur during the construction process of the project.At present,grouting is used as an effective method to manage sudden water,so that the slurry is combined with the fracture surface and the seepage channels within the rock mass are blocked after solidification and hardening to improve the resistance to deformation and stability of the rock mass.In this thesis,Synfrac software is used to generate fracture structures with different roughness,and N-S equations and level set methods are used to numerically simulate fracture structures with different fractal dimensions and slurries with different rheological parameters.The effects of fracture roughness,grouting pressure,yield stress and plastic viscosity on the slurry diffusion process are discussed and the following conclusions are obtained.(1)The volume of the slurry at different plastic viscosities and yield stresses both increase gradually with grouting time,and the growth rate decreases with increasing time.In addition,when the grouting time is short,both have a small effect on the volume;when the yield stress and viscosity of the slurry are the same,there is a critical grouting time that allows the slurry to diffuse to a steady state.(2)The slurry with different rheological parameters diffuses from the grouting hole in all directions and at approximately the same rate,with the slurry diffusion pattern showing symmetry along both axes.The increase in slurry viscosity leads to a decrease in slurry velocity and a decrease in diffusion volume.The slurry diffusion area does not change significantly with the change in yield stress.(3)As the grouting pressure increases,the volume of slurry diffusion gradually increases,the stronger the mobility energy of the driving slurry,which can be the first to diffuse throughout the fissure space;an isolation zone blocking the water flow is formed in the fissure,and a small portion of the water flows along the fissure boundary to the outlet.When the grouting pressure is low,there is an incomplete filling condition near the grouting hole.(4)The volumetric flow rate of the slurry under water velocity conditions gradually increases with grouting time,and the growth rate of the volumetric flow rate also increases with time,with an almost linear relationship between the two in the early grouting stage.When the grouting time is short,the effect of water velocity on the volume is small;the difference in volume of slurry at the later stage of grouting is small and reaches a stable peak state.When the water velocity is higher,the slurry is scoured by the flowing water and cannot be deposited in the fissure.(5)When the fractal dimension is small,the slurry can be deposited rapidly in the fracture and sealed,and the flow of water does not continue towards the fracture exit,so the grouting seal is more effective in this case.The slurry fills the fracture with unevenness before spreading in all directions,so the ’filling-diffusion’ process is repeated throughout the grouting process.