Abstract: As an anti-floating structure, uplift piles are widely used because of their bidirectional axial resistance characteristics. However, the influence of interface roughness on the axial performance of uplift pile remains to be further explored. Based on the in-house pull-out test platform, an aluminum model pile was used to conduct the pull-out model test under monotonous load in dense medium and coarse sand. The strain of the pile was obtained by the strain gauge attached to the shaft of the model pile. The test results show that the model pile with Horvath interface roughness factor of 0.124 is the most similar to the grouted cast-in-place bored piles. The load-displacement of the uplift pile can be divided into three stages: namely, pre-peak growth, post-peak softening and residual stage. Both interface roughness and overburden load are beneficial to increase the ultimate axial capacity of pull-out piles. Increasing interface roughness can effectively slow down the strain softening rate, and increasing overburden load can effectively increase the residual bearing capacity of pull-out piles. The peak axial force of various sections of the uplift pile is synchronized. The axial force of each section decreases with the increase of depth, and the decreasing rate tends to expand. According to the pile soil interface, the pile shaft resistance distribution can be divided into three types: gradually increasing, first increasing and then decreasing, and continuous increasing. The increase of overburden load can improve the position where the maximum shaft resistance is exerted.

Key words: Model Test, Uplift Piles, Interface Roughness, Pull Out Capacity, Pile Shaft Resistance