Buckling failure numerical analysis of HDPE pipes used for the trenchless rehabilitation of a reinforced concrete sewer

• We identified the reasons for the buckling failure of the HDPE rehabilitation pipes.
• We analyzed various methods of designing PE pipes against buckling.
• We showed the scale of discrepancies for the results from various calculation methods.
• We discussed other important factors for consideration when checking the buckling.

The first part of the paper presents a study of a buckling failure of an HDPE pipe of 1091 mm in OD, which was applied for the trenchless non-structural rehabilitation of a leaky reinforced concrete sewer main of 1200 mm in ID. The buckling failure occurred 1 year after its installation. The paper deals with the problem, faced by an expert, who wants to find out the reasons for buckling of HDPE rehabilitation pipe some time after the failure occurred. The aim of the second part of this paper is to compare the analytical methods of checking buckling failure of plain pipes used in Europe (two German and one Scandinavian methods) in order to evaluate the discrepancies in the obtained results and their causes. The paper specifies other factors influencing the scale of discrepancies (different recommendations concerning the value of reduction coefficient, which included the influence of pipe deflection on the decrease of the critical buckling pressure value). Additionally it discusses factors, which should be considered when checking buckling requirement. As some manufacturers of HDPE pipes with profiled walls did not develop any nomograms allowing to define critical buckling pressure it was needed to check if those three procedures for checking the buckling requirement for plain HDPE pipes can be applied for HDPE pipes with profiled walls, which failed after some time. It was found out that the discrepancies of the obtained results are not so high to reject those methods. Many additional factors, which could have more significant influence than the type of the applied calculation method, were listed.