Abstract: With the development of cities, the greening of urban roads is improving; but meanwhile the roots of street trees have also led to damage to road surface. In this study, we examined the damage and characteristics of horizontal roots on pavement surface in consideration of root depth and road condition by using the particle flow method. Research results demonstrated that the uplift height of concrete pavement was 41% of that of soil pavement, indicating that the damage of root diameter to pavement can be effectively reduced. Given the same root diameter, smaller root depth gave rise to higher upheaval of road surface; greater difference between uplift height of concrete pavement surface and soil surface resulted in more severe damage. The soil displacement in the upper part of the root of soil pavement and brick pavement displayed an inverted splayed shape and that in the lower part circular, while the soil displacement around the root of concrete pavement was approximately circular. The shear capacity of soil and the bearing capacity of compressive deformation was correspondingly large when the root depth was large. Overall, we suggest to prevent from root damage to the pavement by controlling the depth of roots, by applying cement mortar bricks and embedding steel bars into concrete pavement.

Key words: road damage, street tree, horizontal root, particle flow, uplift height, shear strength, compressive deformation