Determining the wall thickness of flexible polymer liners
for the rehabilitation of III state class pipelines

Summary

Rehabilitation of damaged gravity sewer pipelines using flexible polymer liners, that utilize reactive resin systems as a binder, involves installing a new polymer pipe inside the existing pipeline. The wall thickness of the new pipe must ensure the static stability of the «new polymer pipe – pipeline being restored» system throughout the pipeline entire service life. An old pipeline of state class III is characterized by longitudinal cracks and significant deformations caused by the changes in soil parameters, as well as by the appearance of voids in the sealing area, so that it cannot independently support loads for an extended period. A method for estimating the static stability of a new polymer pipe-pipeline-soil system is presented with account of the properties of the sealing soil and pipeline ovalization. The main loads acting on a new polymer pipe during the rehabilitation of pipelines with longitudinal cracks (state class III) are determined. An algorithm for calculating the wall thickness of a flexible polymer liner for the rehabilitation of pipelines in this condition is proposed, depending on the applied loads. As an alternative to using special foreign programs for determining the wall thickness of a flexible polymer liner, a calculation method is proposed that provides for determining the liner wall thickness using tables and graphs while restoring a pipeline of state class III under the effect of soil pressure, groundwater, and traffic loads.

Key words

water disposal system , flexible polymer liner , static calculation , pipeline rehabilitation