冻融作用下基桩竖向振动动力特性研究

主要研究三维轴对称条件下饱和双层土中基桩竖向振动,通过建立饱和双层土中桩竖向振动问题的简化层间连续模型,求得了桩顶动力响应频域解析解及时域响应的半解析解,分析了冻融作用对基桩竖向振动的复动刚度的影响。提出在多年冻土地区或季节性冻土地区进行动力基础设计时,应以最不利情况为设计对象。对多年冻土,应以上部出现的最大融深来考虑,对季节性冻土,则应以未冻土来考虑。在多年冻土地区的动力基础施工中,应尽量保持地基的冻结状态,并指出冻融作用会对基桩的检测工作会产生一定的影响。

Dynamic response of vertically vibrating pile during freezing and thawing

Dynamic responses of vertically vibrating pile were investigated under the axisymmetric condition. A simplified model to study the vertical vibration of pile installed in double layered saturated soil was founded firstly. Then an analytical solution in frequency domain and a semi-analytical solution in time domain were derived. The effects of frost and thaw on the complex stiffness of vertically vibrating pile were analyzed. A viewpoint was proposed that it should be based on the most disadvantageous situation for the dynamic foundation design in permafrost or seasonally frozen regions. For the permafrost, and for the seasonally frozen ground it should be based on the low limit of permafrost and on the unfrozen soil respectively. For the construction of foundation in the permafrost, the frozen soil should be maintained in its original state as rigorously as possible. Finally, the influence of the frost action on the pile test was illustrated.