This paper presents a numerical method to efficiently calculate the required overpressure for hydraulic pile extraction. The method uses a one-dimensional (1D) model involving two steps: (1) the steady state hydraulic pressure distribution is calculated for a unit pressure using a finite element model and (2) the required overpressure is calculated using finite element limit analysis. This combined model leads to an efficient calculation tool for estimating the required hydraulic overpressure to extract the pile. The model can also capture other failure mechanisms, such as failure of the pile plug, and the 1D approach allows for alternative soil resistance formulations to be incorporated easily. This allows the method to be used for preliminary analysis as well as detailed extraction assessments for an entire wind farm site. The proposed method is applied to study a pile in sand, clay and layered soil profiles. The analyses in sand show a significant increase in the plug shaft resistance due to the hydraulic gradient, resulting in a super-linear increase of break-out pressure with embedment depth. In clay soils, the break-out pressure increases linearly, but plug failure may occur at large embedment depths. Furthermore, soil layering can have a significant effect on the break-out pressure.

本文提出了一种数值方法，可以有效地计算液压桩提取所需的超压。该方法使用一维（1D）模型，该模型涉及两个步骤：（1）使用有限元模型为单位压力计算稳态液压分配，以及（2）使用有限元极限分析来计算所需的超压。该组合模型导致了一种有效的计算工具，可用于估计提取桩所需的液压超压。该模型还可以捕获其他破坏机制，例如桩塞的破坏，而一维方法允许轻松地引入替代的土壤阻力配方。这使得该方法可以用于整个风电场现场的初步分析以及详细的抽采评估。该方法被用于研究在沙子，粘土和分层土壤剖面中的桩。在砂土中进行的分析表明，由于水力梯度，塞子轴阻力显着增加，导致爆破压力随埋深而呈超线性增加。在黏土中，破裂压力线性增加，但在较大的埋深下可能会发生堵塞故障。此外，土壤分层会对突围压力产生重大影响。