Abstract: The construction technology of strength composite pile is very complex. In order to understand the soil squeezing effect and load transfer mechanism in the piling process, the soil compaction effect test and static cone penetration test of strength composite pile were conducted, and the changes of pore water pressure, total stress and effective stress of soil around the strength composite pile were studied. The test results showed that the soil squeezing effect of strength composite pile decreased gradually along the diameter and increased gradually along the length. In the piling process, the effective stress of the surrounding soil layer increased by 12%−63%, and the side friction resistance of pile increased significantly. The tip resistance and side resistance increased by about 13%−84% and 8%−97%, respectively. Additionally, four load-bearing members with decreasing bearing capacity were formed along the pile diameter through the combination of a variety of strength materials, which realized a better bearing efficiency than that of conventional piles with homogeneous materials. It is consistent with the characteristics that the shear stress and compressive stress of piles caused by the pile top load along the diameter direction and length direction will gradually decay, which is also the source of the significant economic advantage of the strength composite pile.

Key words: strength composite pile, soil squeezing effect, bearing capacity, effective stress, pile-soil interaction