Abstract: Helical pile is widely applied in engineering, such as solar photovoltaic panel, transmission tower, etc. However, the research focused on the vertical or horizontal bearing capacities of helical piles is relatively limited. Especially, the bearing capacity and the bearing mechanism of inclined pile group are still unclear. The comparative model tests of vertical and inclined helical pile groups embedded in sand are carried out. The pile top load-displacement curves and the distribution of soil pressure on the plate of the helical pile group (vertical pile group and 15° inclined pile group) under vertical uplift or lateral load are measured. The ultimate bearing capacity, the load distribution ratio of the plate, and the group effect of inclined helical pile group under vertical uplift or lateral load are comparatively discussed. The results show that the ultimate uplift or lateral bearing capacity of the inclined helical pile group are larger than those of the vertical pile group in the model test conditions, respectively; the peak value of the plate load distribution ratio of the inclined pile group (15°) under the vertical uplift load is smaller than that of the vertical pile group; the maximum lateral earth pressure in the front and behind row of the inclined pile group is both larger than that at the same position of vertical one.

Key words: sand, helical pile, inclined pile group, uplift bearing capacity, lateral bearing capacity, model test