Experimental Investigation of Rehabilitated Steel Culvert Performance under Static Surface Loading: Fid-Bau Portal

Experimental Investigation of Rehabilitated Steel Culvert Performance under Static Surface Loading

Simpson, Bryan / Moore, Ian D. / Hoult, Neil A.

An alternative approach to replacing corrugated steel culverts is to insert a new pipe inside the existing culvert and grout the space between them, a process known as sliplining. Though sliplining is a preferred rehabilitation approach among departments of transportation, very little research has been done to investigate the capacity enhancement provided by sliplining and how the load is shared between components in a sliplined culvert (i.e., the existing pipe, the liner, the grout, and the surrounding soil). A series of experiments was conducted on a deteriorated corrugated steel culvert at two different burial depths (600 and 900 mm) under surface loading before and after the culvert was rehabilitated with a grouted high density polyethylene (HDPE) slipliner. The rehabilitated culvert was found to be considerably stiffer and the diameter changes under surface load were reduced by more than 90% compared with the unrehabilitated culvert suggesting that the negative arching between the pipe and the soil has increased. The strains in the existing pipe were also reduced by more than 70% with negligible strain being measured in the invert of the culvert where the corrosion was concentrated. The results also indicated that when a neat grout with a compressive strength of approximately 30 MPa is used (what could be considered to be high strength in comparison with low density grouts featuring entrained air), the existing pipe and the grout carry most of the load, and the liner’s main role is to improve the hydraulic conductivity. Additionally, because of the increased stiffness of the rehabilitated pipe, the surrounding soil carries less of the surface load applied above the pipe.