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.

中文翻译：

---

EPR技术研究静载和交通荷载作用下垫层对土管衬管结构的影响

垫层是指放置在管道下方和周围的一层材料，用于提供支撑并防止损坏管道。垫层的影响可以根据各种垫层因素来评估。然而，当前的管道设计方法仅评估静态和交通负载下垫层的影响。隔离交通负载的影响进行单独分析是不可能的，这可能会导致确定基础因素时出现错误。在这项工作中，开发了一个 3D 有限元模型来分析管道与周围土壤之间的相互作用，其中结合了混凝土损伤塑性 (CDP) 模型和界面粘聚模型。有限元计算的结果用于通过进化多项式回归（EPR）开发静态和交通荷载下不同回填土的层理系数的预测模型。然后，考虑管道直径、壁厚、埋深、管道初始劣化和回填类型，开发了层理系数计算范例。结果表明，本文提出的刚度模型提供的现场养护管道 (CIPP) 内衬修复壁厚比 ASTM 标准针对劣化等级规定的值高 39.68%、20.64% 和 −20.64%分别为Ⅰ、Ⅱ、Ⅲ级钢筋混凝土管道结构。而且本文提出的基于整体结构刚度的衬砌设计方法比ASTM标准更加灵活。这些范例使得能够设计出更具成本效益和耐用的 CIPP 排水管道修复设计。