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，加拿大每年投资B美元用于下水道、涵洞和水管维修。这促使决策支持系统的发展，以尽量减少生命周期成本。不幸的是，大多数研究都考虑了管道在其使用寿命内的初始埋置配置，通过考虑管道如何单独降解来设定使用寿命。实际破坏往往涉及土壤和管道成分的变化及其相互作用：刚性管道（粘土、混凝土）通常在水通过接缝流入时回填侵蚀时失效;热塑性管道设计使用“恒定应力”测试来建立材料限制，该材料限制忽略了变化的应力，并且也忽略了土壤退化;铸铁水管大多经历环断裂，这不是内部压力的结果，而是由于霜冻引起的纵向弯曲。考虑到管道和土壤系统的变化以及管道失效的实际机制，需要更好的管道使用寿命。其目标是将改进的管道故障模型纳入与交通和市政工程师合作开发的决策支持系统。主题A（重力流管道）将研究刚性管道在侵蚀回填土中的稳定性，连接系统中不同组件如何相互作用，以及柔性和刚性管道长期性能的影响（包括研究支撑垂直服务连接的接缝的荷载和能力，即接缝），接缝处的水流入如何引起回填侵蚀，热塑性塑料管在复杂应力条件下的长期强度，以及考虑施工和其他影响的金属和混凝土涵洞的长期性能。主题B（压力管道）将研究在霜冻荷载下的供水管道和损坏的铸铁管道的强度。这项工作将涉及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.