后张部分粘结预应力抗拔灌注桩的受力机理研究

随着地下空间的开发和利用，地下建筑结构埋深不断增加。当地下水位较高时，地下结构就会受到较大的浮力，因此需要在结构底板下设置抗拔桩。为了研究后张部分粘结预应力抗拔灌注桩的受力机理，首先通过试验测试了预应力钢绞线和水泥净浆的粘结强度。然后，运用ABAQUS有限元分析软件进行数值模拟，得出了粘结强度参数。在此基础上对后张部分粘结预应力抗拔桩进行数值分析，研究其受力机理，为工程应用提供理论依据。研究表明，后张部分粘结预应力抗拔灌注桩侧摩阻力由桩顶至桩底逐渐增加，持力点主要在桩底部，而预应力的施加不仅可以避免裂缝的产生，还可以抵抗“泊松效应”而产生的“颈缩现象”的影响，对提高桩体的抗拔性能十分有利。

Study on the Mechanical Behavior of Post-Tensioned and Part-Bonded Prestressed Uplift Cast-in-Place Pile

With the development and utilization of underground space in Civil Engineering, the depth of underground structures is increasing. When the ground water level is high, the underground structures will subject to greater buoyancy, so it needs to set uplift piles under the floor structure. In order to study the mechanical behavior of post-tensioned and part-bonded prestressed uplift cast-in-place piles, the bond strength of prestressing steel strand and cement paste are tested firstly. Secondly, the bond strength parameters are simulated with the ABAQUS finite element analysis software. Lastly, the mechanical behavior of post-tensioned and part-bonded prestressed uplift cast-in-place piles is analyzed based on the uplift cast-in-place piles finite element model, which can provide theoretical basis for engineering applications. The analysis results show that the side friction of post-tensioned and part-bonded prestressed uplift cast-in-place pile increases from the top to the end of the pile and the stress point located at the bottom of the pile. Prestressing force can avoid the generation of cracks in the piles. At the same time, prestressing force can also resist the influence of the necking for pile caused by the Poisson effect, and it can increase the tensile properties of piles.