PCCP受载响应分析中三种预应力施加方法的比较研究

Comparative study of three methods for the prestressing simulation in the analysis of load-bearing response of a PCCP

本文重点开展PCCP受载响应分析中三种预应力模拟施加方法的比较研究。将等效荷载法、等效降温法和缠丝模型这三种PCCP的预应力模拟施加方法应用于南水北调中线4m内径的埋置式PCCP,模拟施加其预应力场,并对其进行受载响应的数值模拟分析,还对该PCCP进行了原型压力试验,并将试验结果与计算结果进行综合对比分析。结果表明,计算结果与试验吻合较好,均能反映PCCP的受载响应规律;但等效荷载法不能考虑钢丝的刚度贡献和承载作用,给出的PCCP的起裂荷载和爆管荷载偏低;等效降温法不能反映钢丝的实际应力应变状态;缠丝模型不仅能考虑钢丝刚度贡献和承载作用,反映钢丝的实际应力应变状态,还能描述钢丝与其余部件的相互作用,具有更好的适用性。说明今后更适合以缠丝模型作为PCCP数值模拟分析的基础,进一步对PCCP的断丝响应以及结构安全性进行深入研究。

This paper presents a comparative study of three methods for prestressing simulation in the analysis of load-bearing responses of a PCCP,i.e.equivalent pressure method,equivalent temperature descent method,and wire-wrapping model.These methods are applied to the load-bearing responses of an embedded PCCP used by the south-to-north water diversion project.A prototype test of the PCCP was conducted for the first time.Comparison of the numerical calculation with the test data shows a good agreement,both following a typical trend of the responses.The cracking loads and rupture loads of the PCCP calculated by the equivalent pressure method are too low,as the method can not properly account for the stiffness contribution and the load-bearing function of the wire,while the equivalent temperature descent method fails in the stresses and strains of the wire.The wire-wrapping model owns better applicability.It overcomes the problems in the other two methods,and it can model the interactions between the wire and the other components.This study concludes that the wire-wrapping model should be preferable for the prestressing simulation of a PCCP,and the further studies of the responses to wire-breaking and the evaluations of PCCP structural safety should be based on this model.