摘要: |
Ohio Department of Transportation (ODOT) Construction and Material Specification (CMS) 611 requires a post installation inspection of thermoplastic conduit. The inspection includes visual observation for structural distress and a vertical deflection check via a mandrel or a laser profiler. Conduit exhibiting a vertical deflection exceeding 7.5% of the nominal diameter requires repair or replacement. The industry standard repair method for highly deflected thermoplastic conduit is to utilize a re-rounder to remove the vertical deflection of the conduit. The re-rounder restores the shape of the conduit by vibrating the backfill into consolidation. While the shape may be re-established by removal of the vertical deflection, the impact to the longevity, material properties, embankment above the conduit, and the conduit physical properties is unknown.
The project encompasses two phases. In Phase 1, current practices in Ohio and other states were evaluated and relevant parameters determined. Equipment options for re-rounding were also investigated, and a plan devised for field evaluation of re-rounding techniques. The Phase 2 work includes a field study to document and analyze the effects of re-rounding. The field work will include determining the site conditions before and after re-rounding, installation of pipes with varying site parameters using contractor developed installation plans which define the materials and installation techniques. In addition, a cost-benefit analysis will be conducted that will include a comparison of costs and assessment of risks for re-rounding versus replacement of the conduit. |