Abstract: By using the large-scale model test system, the indoor model tests in the clay soil were carried out, and the macroscopic phenomena of the penetration characteristics of the static piles in the clay soil were obtained. In order to solve the problem of macro and meso mechanical response of the pile body during the pile driving process of the static pressure pile, the continuous penetration process of the static pressure pile was simulated by using two-dimensional particle flow numerical simulation software, and the variation law of the pile pressure force, the pile end resistance and the pile side friction resistance during the static pressure pile penetration process were studied at the fine level. The test results show that the mechanical characteristics of the static pressure pile are closely related to the diameter of the pile, the larger the pile diameter is, the greater the lateral extrusion pressure on the soil, the more obvious the lateral friction resistance of the pile, and the greater the pile compression force. With the increase of the depth of soil entry, the horizontal contact force chain of the soil at the position of the adjacent pile body increases, and the horizontal force chain closer to the pile end is larger, and the dense area of the contact force chain of the soil at the pile end shows a circle.

Key words: jacked pile, sinking process, laboratory tests, PFC numerical, meso mechanical, cohesive soil