变刚度悬臂式双排抗滑桩水平推桩模型试验研究

双排抗滑桩常用于加固大型滑坡，其中悬臂式双排抗滑桩由于施工便利，受到工程界广泛重视。已有研究表明，后排桩承受的滑坡推力大于前排桩，是困扰设计的重要问题。文章借鉴变刚度调平设计原理，通过改变前后排桩间距实现前后排桩刚度的调整，设计了变刚度悬臂式双排抗滑桩支护形式，并进行了室内水平推桩模型试验，得到桩顶及坡顶位移、桩身弯矩以及滑体内土压力分布。结果表明：水平推桩模式下，桩顶位移和桩身弯矩随荷载增大而增大，模型边坡沿着滑动面破坏，根据桩顶的荷载-位移曲线，双排桩在推力作用下的发展过程被划分为三个阶段；适度增大前排桩的桩间距并不会明显降低双排抗滑桩的临界荷载；采用变刚度调平设计悬臂式双排抗滑桩，前排作用被充分调动，前后排最大弯矩差值变小；双排抗滑桩存在明显的三维土拱效应，在推力方向上被划分为后排桩后土拱效应、桩排间土拱效应、前排桩前土拱效应，在深度方向上，滑体中部土拱效应与滑体下部有所不同；适度扩大前排桩的间距，桩排间土体保持稳定，未见土体绕流现象，桩排间土拱效应作用明显。

Model test of cantilever double-row anti-slide pile using horizontal pushing method

Double-row anti-slide piles are usually used to reinforce large-scale landslides, and the cantilever-type are popular by engineers for the convenience in construction. The key step of design is to determine the landslide thrust acting on the front and back row piles. However, the research showed that the landslide thrust on the back-row piles is greater than that on the front-row piles. In order to solve the problem, a model test was designed by adjusting the stiffness of front and back row piles. The testing results showed that the pile head displacement and bending moment increased with the loading. The model slope destroyed along the sliding surface under the horizontal load. The development process of double-row piles under the thrust could be divided into three stages. The ultimate resistance of double-row anti-slide piles would not be significantly reduced when the pile spacing of front-row pile increased. By adjusting the stiffness between the front and back row piles, function of the front-row piles was fully motivated, the maximum bending moment between front and rear rows was reduced. The test also showed that there was obvious soil arching effect between piles, which could be divided into three zones, the back-row one, the front-row one and the one between the pile rows. Enlarging the spacing of the front row piles enhanced the soil arching effect between the piles. The distribution of soil pressure as spatial characteristics.