Abstract: Particle movement in rock fissures, influenced by dynamic water action, often leads to infiltration damage. To address the random and hidden nature of natural rock fissures, a fissure channel with a rough joint surface was constructed using a three-dimensional Weierstrass-Mandelbrot fractal function. A transparent and refined fracture channel was obtained using 3D printing technique, and the movement of particles in the fissures under the action of moving water was studied using microfluidic control instruments. The influences of the degree of fissure roughness, the ratio of particle size to fissure width (it is referred to “particle-to-gap size rate” in text), and the seepage pressure on particle initiation and transport were analyzed to deduce the possibility of infiltration damage in rock. The results show that of particle movement in rock fissures is related to three factors: the degree of fissure roughness, the water pressure, and the particle-to-gap size rate. Larger fissure roughness or larger particle-to-gap size rate makes particle movement less likely, reducing the possibility of seepage failure. At the same time, the water pressure is the dominant factor in particle movement, the impact of particle-to-gap size rate on particle movement is related to water pressure. There is a specific water pressure critical value. Below this value, the influence of particle-to-gap size rate on average movement speed is not obvious. Beyond this value, the influence increases significantly. The critical water pressure value is related to the degree of fissure roughness. The rougher the fissure, the higher the critical water pressure.

Key words: rock fractures, particle movement, dynamic water pressure, fractal dimension, laboratory tests