预制混凝土桩体抗扭设计及试验

为了解决预制混凝土螺旋桩的抗扭问题，对预制混凝土桩体的抗扭性能进行了加强设计及试验研究。采用提高混凝土强度等级、配置螺旋箍筋、施加一定预应力等措施来提高预制混凝土桩体的特征扭矩；对试件的破坏特征、开裂扭矩、极限扭矩及扭矩-扭率关系等抗扭性能进行了研究。结果表明：按估算公式计算的预制桩体开裂扭矩与试验结果基本吻合，但存在一定误差；应选用预应力混凝土结构作为预制混凝土螺旋桩的桩型，而不选用增加配置螺旋箍筋的普通钢筋混凝土结构。

Design and Experiment on Torsional Behaviors of Precast Concrete Pile Body

In order to solve the torsional problem of precast concrete screw pile in construction, the torsional behaviors of precast concrete pile body were designed strongly and studied by experimental method. The methods of improvement of concrete strength level, distribution of spiral hoop and application of some prestresses were used to improve the characteristic torsion of precast concrete pile body. Meanwhile, the torsional behaviors, such as destructive characteristic, cracking torsion, ultimate torsion and the relationships between torsion and angle of twist per unit length were studied. Results show that the calculated values of formulas of precast concrete pile body are in reasonable agreement with experimental values, and prestressed concrete structure should be selected to make precast concrete screw pile instead of common reinforced concrete structure with high ratio of spiral hoop.