Effects of Rehabilitation Methods on Performance of Buried Corroded Metal Pipes

Effects of Rehabilitation Methods on Performance of Buried Corroded Metal Pipes—Numerical Study

Jawad, Saif / Al-Naddaf, Mahdi / Han, Jie / Rahmaninezhad, S. Mustapha

Some corroded corrugated metal pipes (CMPs) buried under roadways have been reached the end of their service life. Maintenance, which includes excavation and replacement of the damaged pipes, will disrupt the traffic and require a considerable cost. Trenchless methods of rehabilitation, such as sliplining and cement mortar (spray-on) lining, have been increasingly utilized to repair buried damaged metal pipes. However, few studies have been carried out to assess the performance of the rehabilitated corroded pipes. In this study, a numerical analysis was carried out to assess the performance of buried corroded CMPs rehabilitated with sliplining and cement mortar lining methods. The available field test results of the corroded CMP before and after rehabilitation were used to verify the numerical models. The modeled CMP had an inside diameter of 600 mm and a wall thickness of 2 mm, with corroded invert, which was located at 0.4 m depth under the pavement layer. Typical properties of a low-viscosity grout were used to simulate sliplining and cement mortar liner grouts. For the sliplined CMP, a high-density polyethylene (HDPE) liner pipe with an outer diameter of 550 mm and a wall thickness of 20 mm was modelled. In the cement mortar lining method, the thickness of the cementitious liner was 50 or 75 mm. The load-carrying behavior of the rehabilitated CMPs, their horizontal and vertical diameter changes, and settlement of the pavement surface were investigated when the rehabilitated buries CMPs were subjected to surface loading. The results show that the cement mortar rehabilitation method provided approximately 10% higher load-carrying as compared with the sliplining method at a same vertical diameter change. The rehabilitation by sliplining and cement mortar lining methods notably reduced the displacement of the pavement as compared with no rehabilitation.