砂土中螺旋桩纵向振动响应的模型试验研究

Model test study on longitudinal vibration response characteristics of screw piles in sand

为了讨论桩体几何结构对螺旋桩纵向振动响应特性的影响,通过自制的桩-土动力相互作用模型试验平台,对砂土中不同几何结构的螺旋桩模型的纵向振动响应进行了研究,进而讨论了桩体几何结构对螺旋桩纵向振动响应特性的影响。作为对比,给出了直桩模型的纵向振动响应特性。通过模型振动试验,研究了桩体几何参数(叶片距宽比、叶片外伸比)、载荷幅值对螺旋桩模型和直桩模型纵向振动响应特性的影响。结果表明:桩模型的共振频率随桩体承受载荷幅值增大而减小;在相同纵向激励荷载作用下,螺旋桩模型的共振频率随叶片外伸比的增大而增加,但不随距宽比的变化而发生显著变化;与直桩模型相比,在承受相同载荷且桩体直径均相同的条件下,螺旋桩模型共振频率远大于直桩模型的共振频率。

To discuss the influence of the geometry of screw pile on its longitudinal vibration response characteristics,a pile-soil dynamic interaction model test platform is made to study the longitudinal vibration response characteristics of the screw pile model with different geometric structures in sand. The vibration response characteristic of straight pile model is given to compare with screw piles. The influence of the pile geometric parameters(blade spacing-width ratio,blade extension ratio),the loading amplitude on the vibration response characteristics of screw pile and straight pile are analyzed in detail. The experimental studies show that the resonant frequency of the pile model decreases with increasing load amplitude. Under the same longitudinal excitation load,the resonance frequency of the screw pile model increases with the increasing of the blade spacing-width ratio,but it does not change with the change of the blade extension ratio. The resonant frequency of the screw pile model is much larger than the resonant frequency of the straight pile model under the same load and diameter.