Impact of bedding layers to soil-pipe-liner structure under static and traffic loads with EPR technology

Bedding layer refers to a layer of material that is placed under and around a pipe to provide support and prevent damage to the pipe. The impact of the bedding layer can be evaluated based on various bedding factors. However, current pipe design methods only evaluate the impact of bedding layers under static and traffic load. Isolating the effects of traffic loads for separate analysis is not possible, which may cause errors in determining the bedding factors. In this work, a 3D finite element model was developed to analyze the interaction between pipeline and surrounding soil, incorporating a Concrete Damaged Plasticity (CDP) model and an interfacial cohesive model. The results calculated from the FEM was used to develop prediction models for bedding factors of different backfills under static and traffic loads by Evolutionary polynomial regression (EPR). And then, bedding factor calculation paradigms were developed by considering pipe diameter, wall thickness, buried depth, initial pipe deterioration, and backfill type. The results indicate that the proposed stiffness model in this paper provides a Cured-In-Place Pipe (CIPP) lining repair wall thickness that is 39.68 %, 20.64 %, and −20.64 % higher than the values specified by the ASTM standard for deteriorated Class I, II, and III reinforced concrete pipeline structures, respectively. Moreover, the lining design method based on the overall structural stiffness proposed in this paper is more flexible than the ASTM standard. These paradigms enable the design of more cost-effective and durable CIPP rehabilitation designs for drainage pipes.