Laboratory evaluation of installation of a steel-reinforced high-density polyethylene pipe in soil

A new steel-reinforced high-density polyethylene (SRHDPE) pipe has been recently introduced to the market. The pipe combines high-strength helically wound steel reinforcing ribs with corrosion-resistant high-density polyethylene (HDPE) resin cover and liner. The behavior and performance of such a new pipe have not been well studied under a shallow cover during installation. To investigate the behavior and performance of the SRHDPE pipe during installation, a test section was constructed in a large test box in laboratory. This investigation was performed in the box with a trench condition under a 0.61 m thick soil cover with sand as the bedding and backfill materials and aggregate as a base course. The pressure distribution around the pipe, deflections of the pipe, and the strains on both steel and polyethylene plastic were measured during the installation. No cracking of the plastic liner or plastic cover was observed during the experiment. The test results and analysis concluded that the pipe wall-soil interface should be considered fully bonded to be conservative. The formula proposed by Masada and Sargand reasonably predicted the peaking deflection of the pipe in the compacted sand backfill. The modified Iowa formula by Watkins and Spangler under-predicted the deflections of the SRHDPE pipe during the installation more than that by the solution proposed by McGrath. The pipe wall area was strong and stiff enough to resist the wall thrust during the installation. The highest measured strains recorded on steel and plastic during the installation were below the maximum permissible limits. (C) 2015 Elsevier Ltd. All rights reserved.