Performance evaluation of water pipelines retrofitted with cured in place pipe liner technology under transient earthquake motions

In past earthquake events, the seismic vulnerability of underground pipelines caused significant life and economic losses. Seismic retrofit of critical underground pipelines has become an urgent need of our society to improve the performance and serviceability of these critical lifeline systems as well as to enhance public safety. The cured in place pipe (CIPP) liner technology consists of installing flexible polymeric liners with thermosetting resin inside existing pipelines. Compared with traditional expensive and disruptive excavation and replacement of aging and structurally unsound pipelines, CIPP provides an economic and environmentally friendly alternative for pipeline rehabilitation. However, the lack of verification and quantification of the seismic performance of CIPP liner under transient ground deformation remains a critical deficiency in current practice. Full-scale quasi-static and dynamic tests were performed on four water-pressurized ductile iron (DI) pipelines (6.0 in. nominal diameter and 30 ft. nominal length) reinforced with the Starline® 2000 liner, one type of CIPP liner manufactured by Progressive Pipeline Management, LLC, West Deptford, NJ. This paper characterizes the behavior of the liner-strengthened DI pipelines under static loading and also investigates their seismic response under transient ground deformations (TGD). Moreover, based on the joint response under quasi-static loading, a new constitutive numerical model is proposed for capturing the longitudinal behavior of liner-reinforced joints that considers strength degradation and energy dissipation. Both the test results and numerical analyses indicate that CIPP liner provides substantial longitudinal strength to the joints of DI pipelines and improve significantly their seismic behavior under high intensity of TGD.