Thickness optimization of semi-structural CIPP pressure pipe liners: A mathematical modeling approach

This paper introduces a novel mathematical model to optimize the thickness of semi-structural liners in Cured-In-Place-Pipe (CIPP) rehabilitation based on the host pipe holes criterion defined in current standards. The model considers the residual structural mechanical properties of the damaged host pipe, and holes are defined considering the direction, the area, and the perimeter of the host pipe hole, providing a more accurate estimation of the liner behavior. Results indicate potential thickness reductions of 20%–40% for circular holes, while non-circular holes offer even greater optimization possibilities ranging from 40 to 80%. Moreover, a full-scale test was conducted on a reinforced concrete host pipe of DN 400, damaged with three holes 150 mm in diameter. The full-scale test results were used to refine the numerical model employed in developing the mathematical model, ensuring its accuracy and reliability.