经垫衬法修复后铸铁管道接口力学性能试验

Experimental study on mechanical properties of ductile iron pipeline rehabilitated by corrosion protection lining

摘要:

垫衬法是指采用柔性的高密度聚乙烯速格垫作为内衬材料并使用V型速格键与高徽浆进行贴合并填充管道接口缝隙的一种管道非开挖修复技术.垫衬法可有效提高供水管道的过流量、耐腐蚀性与防渗漏性能,避免大规模开挖与修复.为研究垫衬法修复对管道承载力和变形能力的提升效果,采用垫衬法对现有DN400球墨铸铁供水管道的承插式接口进行修复,在外部无覆土、管内注水条件下,对修复后球墨铸铁供水管道承插式接口进行拟静力拉拔与弯曲试验,分析了修复后管道接口的轴向抗拔与横向抗弯曲的力学性能与破坏模式,建立了修复后管道接口失效判定准则.对比垫衬法修复前后管道接口的力学性能表明,该方法能显著提高管道接口的抗拉、抗弯承载力.本试验研究成果为管道垫衬法修复技术的适用性与施工工艺的提升提供了必要的试验数据与理论依据.

Abstract:

Corrosion protection lining, as a type of trenchless rehabilitation technology, consists of installation of flexible high-density polyethylene corrosion protecting liner with V-shaped shear keys inside the existing pipe and filling the gap between the pad and the pipe with cement paste. The corrosion protection lining can effectively improve the flow capacity, corrosion resistance, deformation resistance, and anti-leakage performance of the pipeline and avoid large-scale excavation and replacement of components. To investigate its improving effect on the bending capacity and deformation resistance of ductile iron pipeline, corrosion protection lining was applied to the rehabilitation of the existing DN400 ductile iron water pipeline push-on joints, and a series of pseudo-static tensile and bending test were performed on the push-on joints of the water-pressurized ductile iron pipeline without soil coverage. The mechanical behaviors and failure modes of the push-on joints rehabilitated by the corrosion protection lining were investigated under both axial tensile loading and lateral bending. Failure criteria of the liner-reinforced pipeline joints were established. Comparison of the mechanical properties of the pipeline before and after rehabilitated by corrosion protection lining show that corrosion protection lining can significantly improve the axial tensile and flexural bending capacity of the push-on joint. The experimental results validate and support the application of corrosion protection lining to improving structural behaviors of the burial water pipelines in engineering practice.