Pore tortuosity represents the complexity of fluid flow paths in soil and is a key parameter for analyzing soil infiltration properties. However, most existing pore tortuosity models are general-purpose, making them less suitable for soil-rock mixtures, which exhibit distinct characteristics such as a wide grain size distribution and complex pore structure. To develop a computational model for soil-rock mixtures that accounts for the effects of coarse particle crushing on pore tortuosity, soil particles were assumed to be circular with varying sizes. And a lognormal distribution function was used to represent soil gradation in different cases, while obstruction angle and anisotropy parameter were introduced to characterize the particle dispersion pattern. A pore tortuosity calculation model influenced by multiple factors was finally developed based on the laminar flow of fluids in soil-rock mixtures. Using programming software and numerical simulation methods, seepage simulations were performed on soil-rock mixtures with varying soil gradation and initial porosity. The relative error between the theoretical and simulation results was within 2%, demonstrating the validity of the proposed model. The analysis of the model influencing factors indicated that changes in particle gradation significantly affect pore tortuosity. Pore tortuosity decreased as coarse particle content increased, and the absence of macroparticles further reduced pore tortuosity. As the obstruction angle and anisotropy parameters increased, the pore tortuosity also increased. A significant negative interaction was observed between porosity and the other factors. When porosity is high, pore tortuosity converges to 1, indicating that porosity becomes the dominant factor affecting pore tortuosity. Among the above four influencing factors, the degree of influence on pore tortuosity in the soil-rock mixture followed the order: particle gradation (mass fractal dimension) > anisotropy parameter > porosity > obstruction angle. The grey correlation values of the mass fractal dimension and anisotropy parameter exceeded 0.95, indicating a strong correlation.