长短桩组合排桩悬臂支护工作机理试验研究

Experimental study on cantilever contiguous retaining piles with different lengths

采用排桩作为基坑支护结构时,桩长必须满足允许变形、抗倾覆、整体稳定、抗隆起稳定等要求。而这些不同的要求需要的桩长是不一样的。目前的设计方法是,对排桩中所有的桩都取相同桩长来满足这些要求。提出了在排桩中采用长、短桩组合支护的方法,这样既可满足设计要求,又可降低造价。用实验的方法对基坑开挖过程中悬臂不等长支护桩的桩顶位移和桩身弯矩进行了研究,对比不同排桩桩距时,分别采用等长桩与不等长桩的支护效果,揭示了不等长支护桩长桩与短桩的协同工作机制。

When the contiguous piles are adopted as the retaining structure,the length of piles has to meet the design requirements including the allowable deformation,overturning,sliding and heaving.These requirements may require different pile lengths.However,it is quite common in practice that all piles in the contiguous piles are of the same length,which is the largest one of all the pile lengths regarding to different design requirements.A new concept was presented that the contiguous piles with different pile lengths could be used.It could not only meet all the requirements but also reduce the cost.Model tests were carried out to investigate the behaviors of this kind of contiguous piles.The displacement at the top of piles and the flexural strain in the pile bodies at different depths were measured during the whole excavation process.The behaviors of two types of contiguous retaining piles,i.e.,with different pile lengths and with the same length,were compared.Finally,the interaction between long piles and short piles and their behaviors were clarified..