关键词: 沉桩过程, 挤土效应, 位移贯入法, 位移轨迹, 桩周应力

Abstract: A two-dimensional axisymmetric model was established based on the finite element simulation software ANSYS to study the compaction effect of jacked pile when it was driven into soil, and the displacement penetrating method was used to simulate the whole process of jacked piles. By obtaining the displacement trajectory of the soil around the pile during the punching processes, the internal mechanism of the compaction effect was revealed, and it was found that the effect of the punching processes on the soil can be summarized into three stages: compact-extrusion-towing. After deducting the initial geostress, the distribution law of stress increment field in the soil was analyzed in depth. It was considered that the expansion pressure was composed of three parts: expansion pressure of the gravityless foundation, the ground stress confining pressure and the expansion pressure increment caused by confining pressure. The finite element calculation results were compared with the theoretical solution, and it was found that the expansion stress of the theoretical solution was too large as not considering the influence of the vertical plane deviator stress, and the axisymmetric solution based on the expansion theory of cylindrical holes can only be applied to the case in which the internal friction angle is large.

Key words: jacked pile processes, soil extrusion effect, displacement penetration method, displacement trajectory, stress around the pile;