水平循环荷载下风电机桩基础离心模型试验研究

Centrifugal model test of pile foundation for wind power unit under cyclic lateral loading

在近海风力发电工程中桩基是常用的基础型式,海上风力发电机桩基础一般建立于复杂软土地基、承受着海上风浪、潮流等近似水平向的循环荷载作用,而风力发电机组运行对基础的承载力和变形有严格的要求。因此,研究水平循环荷载下桩土系统变形规律和相互作用机制具有重要的意义。针对典型的近海风机单桩基础,选取典型的饱和砂性土地基,通过离心模型试验的方法研究了水平循环荷载下的风机桩基础的受力变形规律。试验结果表明,水平向循环作用下,桩周围土体中变形主要呈现为挤压或塌陷产生的沉降和水平向变形,变形主要集中在桩周围较小的范围内;变形呈现逐渐累积特性,其大小随着循环次数的增加而增加;桩身弯矩峰值出现在埋深上1/3处,多次循环后的弯矩大小和分布变化不大;桩周围土体中不同位置产生不同的超静孔隙水压力,孔隙水压力发展对土体变形有一定影响。

In offshore wind power project, pile is a commonly used foundation type and is commonly established in soft soil foundations and suffers complex loading combinations, while the bearing capacity and deformation of the foundation is with strict requirements for running of wind power generations. Therefore, studies of behavior and interaction mechanism of pile foundation under cyclic latera! loading have important significance. Centrifugal model tests for typical offshore pile foundation and saturated sand ground are conducted to study deformation characteristics under cyclic lateral loading. Test results show that： under cyclic lateral loading, settlement and horizontal deformation, which is mainly caused by extrusion or collapse, occurs in a limit extent of soil around pile; deformation gradually accumulates with increase of cycles; peak bending moment of pile appears in the 1/3 of burying depth; little change happens in distribution of bending moment with cycles increasing; different excess pore water pressure develops at different locations of soil surrounding pile, which has a certain influence on the foundation behavior.