Abstract: This study is aimed at addressing the challenges in quantitatively characterizing the spatial distribution features and filling volume of overburden fractures during gangue slurry filling. To achieve this aim, the overburden migration patterns and fracture development mechanisms within the stope were systematically investigated. Besides, a quantitative computational model was developed to evaluate cavity and fracture spaces in both caved and fractured zones, and the regulatory effects of key parameters including mining height, rock fragmentation coefficient, compacted zone length of the caved zone, and working face advance length on fracture space evolution were elucidated. The results show that the volume of cavity and fracture spaces in the non-compacted zone of the caved zone is about 2.5 times that in the compacted zone and about 7.5 times that in the fractured zone. On this basis, three gangue slurry interventional filling experiments of different scales were performed, and the flow and diffusion dynamics within the caved zone were analyzed. Furthermore, a theoretical predictive model for gangue slurry interventional filling volumes applicable to both low-level grouting and adjacent grouting methods was established. Field validations demonstrate that gangue slurry exhibits excellent flow and diffusion performance in the caved zone, with model predictions showing strong agreement with actual filling volumes. The proposed framework provides reliable theoretical guidance for gangue slurry filling engineering applications.