Testing the Applicability of Existing Buckling Equations on Spray-Applied Pipe Lining Systems Using Full-Scale Laboratory Testing and Finite Element Modeling

Spray-applied pipe lining (SAPL) is a trenchless technology used to renew water and wastewater infrastructure above and underground by spraying cementitious or polymeric materials into the host pipe. SAPL can be designed to be bonded or non-bonded to the host pipe. When designed as bonded to the host pipe, achieving uniform bonding between the host pipe and the liner is challenging in field conditions. Non-bonded areas create gaps between the liner and host pipe, through which groundwater may seep, creating external pressure on the lining system and, thus, experiencing a buckling effect. In this paper, a polymeric lining system with a small gap between the liner and host pipe was tested to evaluate the buckling effects of the external hydrostatic pressure on the lining system. In addition to the experimental results, Finite Element Modeling (FEM) was used to develop the buckling models of SAPL liner pipes encased in host pipes and was validated by experimental results. After validating the experimental results, different parameters of the design equations were used to develop the FEM models to provide recommendations for improving the AWWA equations.