Abstract: In order to study the formation of shear zone and the evolution of mesostructures in rockfill under high confining pressure, we constructed three different shapes of broken particle clusters by using self-designed program, and randomly generated two-dimensional particle flow samples for biaxial compression test. Results show that when axial strain is 6%, the volume shrinkage of specimen changes to volume expansion; when axial strain reaches 10%, the structure changes in the sample. The formation of shear zone can be clearly reflected by the evolution of micro-structures such as rotation, movement, fragmentation and porosity of particle clusters in the sample; when axial strain reaches 10%, the particle clusters with large rotation amplitude and serious breakage and the region with large porosity both present asymmetric X-shaped distribution, and the X-shaped contour gradually becomes clear.

Key words: rockfill, high confining pressure, particle flow, shear zone, mesostructure