Abstract: The soil arching effect in micro anti-slide pile system has obviously spatial characteristics when bearing landslide thrusts because of pile body large deformation due to its small diameter. Most current research methods could not consider this point, just treat soil arching effect as plane strain problem. Therefore, based on the particle flow code in 3-dimensions (PFC3D), a series of micro anti-slide pile system tests are simulated to study the formation and development process of the soil arching. The simulation results show that the soil arching effect mainly occurs in the middle and bottom of soil body located nearby the slip plane. The soil arching effect located in the top of soil body is affected by the pile displacement which causes the evident horizontal soil arching formed between piles. Pile length and stiffness have little influence on the distribution of soil arching. It is difficult to form soil arching with the increasing of pile spacing.

Key words: landslide, micro anti-slide pile, soil arching effect, particle element, mesomechanics