Abstract: The issue of seepage in fractured rock masses has emerged as a crucial technical challenge in large-scale rock
mass engineering projects,such as geological disposal of high-level nuclear waste,deep geological energy mining,hydraulic engineering,
and deep underground space exploration. Unlike uniform porous media,rocks contain numerous non-uniformly distributed
pores,fractures,and other complex structures,which exhibit significant differences in hydraulic conductivity characteristics,
leading to extreme complexity in the seepage process of fractured rocks. Focusing on fractured sandstone as the research
object,this study first employs nuclear magnetic resonance imaging technology to obtain detailed images of the internal microstructure.
Subsequently,based on image digitization techniques,the main fractures,secondary fractures,and rock matrix are
precisely segmented and extracted. By constructing a numerical rock model that can accurately reflect the complex fracture
(pore) structure and heterogeneous hydraulic characteristics,a comprehensive numerical simulation of the entire seepage
process in fractured rocks under different seepage conditions and fracture properties is conducted. The results indicate that the
seepage velocity and outlet flow rate of fractured sandstone increase with the increase in seepage pressure,fracture aperture,
and fracture number,while they decrease with the increase in fracture roughness and intersection angle. The permeability coefficient
obtained from the simulation analysis is highly consistent with the experimental results and exhibits similar trends. The
permeability coefficient of fractured rocks is positively correlated with the fracture aperture and fracture number,while negatively
correlated with the fracture roughness and intersection angle. The fractured sandstone model based on nuclear magnetic resonance
imaging digitization technology can effectively characterize the complex seepage evolution characteristics of rocks,providing
a feasible method for analyzing the seepage process in fractured rocks. The research findings provide powerful analytical tools and theoretical guidance for the analysis and control of seepage in rock mass engineering.