关键词: 灌注桩, 高频振动, 套管上拔, 大变形有限元法

Abstract: Currently, most of studies on the mechanisms of driving and pulling for Benoto pile sleeve are focused on sleeve driving process. Yet, pulling by high-frequency vibration are deficient. Using the ALE (Arbitrary Lagrangian-Eulerian) method, the finite element-infinite element coupling model is developed to explore the pulling mechanism and influence of parameters on sleeve pulling. The results of numerical analysis show that the process of sleeve pulling by high-frequency vibration can be divided into two stages: the slow and the fast pulling stages. During sleeve pulling, the soil displacements, stresses, void ratio and excess pore water pressure all mutate near the sleeve end, and the change is more significant as approaching to the sleeve center. Therefore, the influence of soil parameters (including soil young’s modulus and soil-sleeve friction coefficient) and vibration hammer parameters (such as vibration frequency and vibration force) on sleeve pulling are investigated. When the soil is soft and the friction of the sleeve-soil is strong, the change of soil displacements and stresses variety are obvious. The parameters of the vibrating hammer only have influence on sleeve pulling speed and soil particle velocity, and hardly have any effect on soil displacements and stresses. When the vibration frequency is close to the natural frequency of soil layers, the pulling resistance is the small. The larger the vibration frequency is, the smaller the influence range of vibration.

Key words: Benoto pile, high frequency vibration, sleeve pulling, Arbitrary Lagrangian-Eulerian method