The Design and Performance of Pressure Pipe Liners under Static and Cyclic Loading: Fid-Bau Portal

The Design and Performance of Pressure Pipe Liners under Static and Cyclic Loading

Allouche, E. N. / Shanghai, G. / Baumert, M. / Amobi, A. / Bainbridge, K.

There is a growing interest in the utilization of structural CIPP liner for the rehabilitation of deteriorated gray cast-iron water mains. However, little data is available on the long-term performance of such rehabilitation systems with respect to static and cyclic internal pressures. Specifically, the impact of the size and the shape of the holes in the host pipe are currently not considered by available design methods. An experimental study was undertaken to develop mathematical relationships between the size and geometry of the hole in the host pipe and the burst pressure of the liner, taking into account both the liner's long-term mechanical characteristic and the loading history (i.e., cyclic loading). Long-term experimental cyclic pressure tests were performed on fully deteriorated pipe specimens lined with a glass fiber reinforced CIPP liner. The tests aimed at measuring the accumulated plastic deformation of the liner under the action of combined fatigue and creep. The specimens were subjected to 350,000 load-unload cycles (60-130-60 psi), the equivalent of 100-year cyclic loading in a typical municipal water distribution system, to evaluate the impact of this loading mechanism on the long-term burst pressure of the lined pipe. The testing program included a host-pipe with gaps ranging between 2" and 4" in diameter. Strain and deflection measurements were taken for each gap in the lined host pipe prior to, during and after each load-unload cycle. In total, over 10 million data points were taken. The data was subjected to a rigorous statistical analysis. Conclusions are made reading the accuracy of creep models commonly used for predicting the mechanical behavior of thermosetting liners, the effect of fatigue and cyclic loads on the long-term performance of glass-fiber reinforce structural liners, and the relationship between the hole diameter, hole orientation, cumulative cyclic loads and the long-term burst pressure of the liner.