## 1 Introduction
[20] utilized 3D printing technology to create precise samples and conducted seepage tests and numerical simulations. They found that fracture roughness and aperture distribution affect the seepage and pressure fields. On the other hand, characterizing the cavity structure of fractures is also a research focus. [PERSON] et al. [21], through improvements to the cubic covering method, filled the fracture space with ultra-thin square plates, describing the anisotropy of fracture space based on the difference in fractal geometric dimensions between the fracture space and parallel plates with equivalent apertures. However, when fractures undergo shear or slip dislocation under complex stress, the void distribution of fractures undergoes intricate changes with dislocation distance, and different stages have varying impacts on seepage [22; 23]. The irregular and unpredictable void distribution of fracture spaces poses a challenge to predicting permeability [10; 24]. Researchers have conducted numerous numerical simulations and experimental analyses to explore the seepage characteristics of non-matching fractures [25]. [PERSON] et al. [26] concluded that asperities' influence on aperture changes during the shear process can not be ignored, significantly affecting the seepage characteristics of the fluid in sheared fractures. [PERSON] et al. [27] summarized coupled shear seepage experiments on fractures, finding that a relatively low-seepage water pressure in the existing test system has a non-negligible impact on the understanding of seepage behavior in a high-stress environment. However, the challenge of maintaining specimen sealing under fracture dislocation conditions in pressure chambers with large shear displacements remains to be addressed and remains a challenge for current research development. Most current experimental techniques face challenges in directly observing the details of fluid flow in actual rock fractures, especially in profoundly understanding the relationship between local geometric characteristics and seepage behavior in rock fractures [28]. This includes non-linear seepage behaviors such as groove flow [19], eddy current [29], and reflux [30]. Research on observing seepage behavior in fractures typically falls into two methods: destructive observation and non-destructive observation. Among non-destructive observation techniques, computer tomography technology (CT) can accurately obtain data on the distribution of voids in fractures without causing artificial damage to the fracture surfaces [16; 31; 32; 33]. Using CT technology, [PERSON] et al. [34; 35] analyzed the flow characteristics of two granite single fracture specimens under confining pressure conditions. They found differences in fracture porosity and permeability under stress influence, but image noise led to insufficient data points. Additionally, based on pore distribution data and numerical simulation methods, the study further investigated the permeability characteristics of actual fractures. This research conclusively confirms the dominant flow behavior within the fractures. Most of the above studies on fracture seepage are based on rock fractures in the original fracture state. However, there are still insufficient studies on the seepage law of mismatched fractures formed by rock dislocations on both sides of fractures. By combining CT experiments and numerical simulation methods, a more in-depth understanding of the evolution of fluid seepage behavior within non-matching fractures can be achieved. In this study, CT technology was utilized to obtain data on the distribution of voids in single granite fractures at different dislocation distances (0-10 mm). The fracture cavity model corresponding to the dislocation state is established, and the numerical simulation of dislocation fracture seepage is carried out. The parameters are quantified based on the fracture surface morphology data obtained by laser scanning to explore the internal causes of fracture space changes.