Abstract: Batter piles are subjected to horizontal loads and meanwhile uplift loads. To investigate the influence of uplift load on the horizontal bearing behavior of batter piles, we conducted indoor model tests on two groups of batter piles subjected to different uplift loads and vertical pile subjected only to horizontal load as control group. According to test result we examined the effects of uplift load on horizontal displacement and horizontal bearing capacity of the top of batter pile, compared the bending moment and shearing force between vertical pile and batter pile, and also analyzed the effects of uplift load on the internal force and frictional resistance of positive and negative batter piles. When uplift load increased from 12.5% to 75% of the horizontal ultimate bearing capacity of vertical piles, the horizontal bearing capacity ratio of positive batter piles increased by 21% while that of negative batter piles decreased by 25%. Uplift load augmented the axial force of both positive and negative batter piles. The larger the uplift load, the greater the axial force of pile. Uplift load also reduced the bending moment and shear force of positive batter piles, hence improving their ability to resisting moment and shear force, while weakened the ability of negative batter piles to resisting bending moment and shear force by increasing the bending moment and shear force. Both positive batter piles and negative batter piles witnessed an upward frictional resistance on the lateral surface of the pile body in the upper section, and downward frictional resistance in the lower section. With the increasing of uplift load, such side frictional resistance increased gradually.

Key words: batter piles, model test, uplift load, horizontal bearing behavior, axial force of piles, frictional resistance