预应力抗浮桩在新城市二期的应用

Application of Prestressed Uplift Pile in New City Plaza Phase Ⅱ Foundation

文章对新城市二期项目基础抗拔桩桩身钢筋进行了分析比较.当抗拔桩采用普通非预应力钢筋时,由于受到桩身裂缝宽度的限制,抗拔桩配置的普通非预应力钢筋应力水平较低.当桩身直径相同时,抗拔桩承受的抗拔力越大,桩身非预应力普通钢筋的应力比呈下降趋势.当抗拔桩承受的抗拔力较小时,桩身直径的大小对桩身钢筋的应力比没有影响,当抗拔桩承受的抗拔力较大时,抗拔桩的桩身直径越大,其桩身钢筋的应力比越高.抗拔桩采用高强预应力钢筋的柱身钢筋用量要明显小于普通非预应力钢筋用量,采用高强预应力钢筋的造价约为普通非预应力钢筋的1/3～1/4.

Reinforcement of uplift pile in New City Plaza Phase Ⅱ foundation is analysed in this paper. Reinforcement of non-prestressed uplift pile maintains a lower stress level when uplift pile using non- prestressed reinforcement because of the limit of pile body crack width. With the same pile diameter, the pile of non-prestressed reinforcement stress ratio decreases when the uplift pile bears more pullout force. The pile diameter has no effect to the stress ratio of reinforcement when the uplift pile bears small pullout force. The stress ratio of reinforcement becomes higher with the growing of pile diameter. The consumption of reinforcement is much lower when the uplift pile is using high strength prestressed reinforcement instead of non-prestressed one. The cost of using high strength prestressed reinforcement is only one third to one forth compare to using non-prestressed one.