实际埋置条件下断丝对PCCP内水压承载能力影响研究

Study on the Influence of Broken Wires on the Internal Water Pressure Bearing Capacity of PCCP under Actual Embedded Conditions

针对某输调水工程在役超大口径PCCP断丝问题,建立有限元分析模型,探究了管身中部预应力钢丝发生不同比例断丝时的管道各部位受力状态。结果表明,随着内水压的增大,断丝管都是管腰处断丝区域外的砂浆保护层最先进入塑性,然后是管芯的顶部、底部和管顶管底的钢筒,最终管腰处预应力钢丝达到其抗拉强度,整管破坏。随着管身中部断丝比例的增加,钢筒和预应力钢丝进入塑性阶段时所对应的内水压值逐渐减小,钢筒总是先于预应力钢丝进入塑性阶段。砂浆保护层和管芯在一定断丝比例之后进入塑性阶段所对应的内水压值维持在一个稳定的数值。研究结果可为实际工程中PCCP出现断丝安全风险后的结构承载能力评估提供依据。

Aiming at the problem of broken wires of super large diameter PCCP in service in a water transfer project, the finite element analysis model is established to explore the stress state of each part of the pipe when the prestressed steel wire breaks in different proportions in the middle of the pipe. The conclusion is as follows: with the increase of internal water pressure, for the broken wire pipe, the mortar protective layer outside the broken wire area at the waist of the pipe enters the plastic stage first, then the top and bottom of concrete core and steel tube, finally the prestressed steel wire at the waist reaches its tensile strength, and the whole pipe is destroyed. With the increase of the proportion of broken wire in the middle of pipe, the internal water pressure of steel tube and prestressed steel wire decreases gradually when they enter the plastic stage, and the steel tube always enters the plastic stage before the prestressed steel wire. After a certain proportion of broken wires, the internal water pressure of the mortar protective layer and the pipe core when they enter the plastic stage maintains a stable value. The research results can provide a basis for the structural bearing capacity evaluation of PCCP after the occurrence of safety risk of broken wires in practical projects.