预应力混凝土竹节桩承载性能对比试验研究

Contrastive experimental study of bearing capability of pre-stressed spun concrete bamboo-shape pile

预应力混凝土竹节桩(简称"竹节桩")是在普通预应力混凝土管桩(简称"管桩")基础上改良而来的新桩型。文章介绍了竹节桩的构造和接桩技术,并通过现场静载试验,对竹节桩在软土地基中的承载性能进行了对比研究。试验表明:竹节桩的单桩竖向抗压极限承载力与管桩和预应力混凝土空心方桩(简称"方桩")相比,均能提高20%左右,单桩竖向抗拔极限承载力比管桩提高60%以上。竹节桩由于设置了环向、纵向凸肋,改变了桩-土接触方式和桩身粗糙度,有利于桩侧摩阻力的充分发挥。在荷载水平较低时,桩顶位移曲线近似为直线,当荷载增加到一定程度时,会在土体中形成一个直径与环向凸肋大小相当的圆筒形剪切滑动面。

Pre-stressed spun concrete bamboo-shape pile（PSCBP） is a new type of pile which is devel- 0ped on the basis of traditional pre-stressed spun concrete pipe pile（PSCPP）. The structure and mechanical bonding technology of PSCBP are introduced, and its bearing capability in soft soil is researched based on static load tests. The results show that the vertical ultimate bearing capacity of sin- gle PSCBP increases by 20% compared with that of PSCPP and pre-stressed spun concrete square pile （PSCSP）, and the vertical uplift ultimate bearing capacity of single PSCBP increases by over 600/6o compared with that of PSCPP. Due to the annular and longitudinal convex rib, contact area between the pile and soft soil and pile roughness increase. In this case, the side friction of PSCBP is fully exerted. The curves of displacement at the top of the PSCBP are similar to straight lines in the low load. When the load increases, a cylindrical shear plane which is same as annular convex rib in diameter will be formed in the soft soil.