Abstract: The force situation and sliding channel are very complicated when particle system is squeezed. The mechanical response and structure changes of two-dimensional lattice pile system of granular material in the process of being pressed were experimentally investigated. The structure collapse and self-organization behavior of the particle system were observed when being squeezed. Based on the experimental results, the relationship between the horizontal pressure distribution, the sliding channel or the reorganization structure and the stacking angle as well as the boundary friction factor was discussed. According to the theory of statics, different force mechanisms about the boundary particle and the central one were analyzed. Studies have shown that compared with rough wall, smooth wall is easier to become a sliding channel for particles, so the force chain formed by the particles is unstable, which means it will easily lead to structural collapse.The friction factor on side wall wouldn't have a significant impact about the stress distribution at different heights. In fact, the recombination of force chain is the main factor leading to stress redistribution at different heights.

Key words: slide channel, geometry, boundary friction, granule matter