Performance assessment of buried pipes: service life and pipe-soil stability over time

我们的许多埋地管道都有50多年的历史，加拿大每年在下水道、涵洞和水管维修上投资B美元。这促使了决策支持系统的发展，以最大限度地减少生命周期成本。不幸的是，大多数研究都考虑了管道的初始埋藏配置对其使用寿命的影响，通过考虑管道本身的退化来确定管道的使用寿命。实际失效往往涉及土壤和管道组件及其相互作用的变化：刚性管道(粘土、混凝土)通常在回填水通过接缝时受到侵蚀时失效；热塑性管道设计使用“恒定应力”测试来确定材料极限，该测试忽略了不同的应力，也忽略了土壤的退化；铸铁给水管道大多发生环形断裂，不是由于内部压力，而是由于霜冻造成的纵向弯曲。考虑到管道和土壤系统的变化以及管道失效的实际机制，需要更长的管道使用寿命。其目标是将改进的管道故障模型纳入正在与交通和市政工程师合作者开发的决策支持系统中。主题A(重力流管道)将研究受侵蚀回填土中刚性管道的稳定性、接缝系统中不同组件如何相互作用以及对软管和刚性管道的长期性能的影响(包括研究支撑垂直服务连接的接缝(即立管)的载荷和容量)、接缝处的水流入如何导致回填土侵蚀、热塑性塑料管道在复杂应力条件下的长期强度，以及在考虑施工和其他影响的情况下金属和混凝土涵洞的长期性能。主题B(压力管道)将调查在霜冻负荷下的供水管道和劣化的铸铁管道的强度。这项工作将包括在五年的资助期内培训六名硕士和六名博士生。

Many of our buried pipes are more than 50 years old, and Canada invests $B's each year on sewer, culvert and water pipe repair. This has prompted the development of decision support systems to minimize life cycle cost. Unfortunately, most research has considered the pipe in its initial burial configuration over its service life, setting that service life by considering how the pipe alone degrades. Actual failure often involves changes in soil and pipe components and their interaction: rigid pipe (clay, concrete) generally fails when backfill erodes as water flows in through joints; thermoplastic pipe design uses 'constant stress' testing to establish material limits which ignores varying stresses, and also neglects soil deterioration; cast iron water pipes mostly experience ring fractures, not a result of internal pressure but of longitudinal bending due to frost. Better pipe service lives are needed, considering changes in the pipe and soil system and the actual mechanisms of pipe failure. The goal is to incorporate improved models of pipe failure into decision support systems being developed with collaborators for transportation and municipal engineers. Theme A (Gravity flow pipes) will study the stability of rigid pipes in eroded backfill, how different components in joint systems interact and the implications for long term performance of flexible and rigid pipes (including a study of the loads and capacity of joints supporting vertical service connections, i.e. risers), how water inflow at joints induces backfill erosion, the long term strength of thermoplastic pipes under complex stress conditions, and the long term performance of metal and concrete culverts considering construction and other effects. Theme B (Pressure pipes) will investigate water supply pipes under frost loads and the strength of deteriorated cast iron pipes. The work will involve training of six MSc and six PhD students over the five year funding period.