Abstract: A formulation method for variable radius proportional clump structure is proposed according to the particle flow method. The effects of mesoparameters and meso-structural characteristics of particle flow on the compressive and tensile properties of simulated rocks are investigated. A clump particle flow structure is constructed, which is suitable for the mechanical characteristics of granite. The reliability of clump structure with variable radius ratio and meso-mechanical parameters is verified. The particle flow models for deep caverns with different sizes are developed, and the scale effect of macro fractures of deep surrounding rock is evaluated. The research results show that the tensile compression ratios of ball and clump models are less sensitive to the changes of meso parameters, and the mechanical properties of variable radius proportional clump model are more sensitive to the changes of particle size and proportion. Using the clump models with different particle size ratios, the compressive and tensile strength curves and fracture modes of numerical simulations and experimental tests are investigated. A good compliance is observed between the numerical and experimental findings. In the small-scale particle model, the fracture zones of the surrounding rocks are mainly broken in local area. By increasing the particle model scale, the clear shear-slip fracture characteristics appear. Simulating the fracture properties by the particle flow model for deep surrounding rocks exhibits clear macro-scale effects.