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Experimental testing and finite element analysis of segmented water pipeline
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Date
2024
Authors
Zhang, Qinglai
Journal Title
Journal ISSN
Volume Title
Publisher
University College Cork
Published Version
Abstract
Underground pipeline networks are crucial for the serviceability of sustainable water distribution in contemporary society. Nonetheless, thousands of miles of segmented pipeline infrastructure are susceptible to substantial damage from natural disasters, such as earthquakes and landslides, particularly at the vulnerable joint sections.
To enhance the resilience of the segmented pipelines, many previous studies have already investigated various types of pipeline joints and materials in both academia and industry. Over the years, Ductile Iron (DI) Pipes have already been widely used in buried underground infrastructure, owing to their durability and reliability under various soil and loading conditions. On the other hand, Polyvinyl Chloride-Oriented (PVCO) pipelines have emerged as a novel alternative in recent years due to its cost-effectiveness, environmental friendliness and easy installation. Both are valued for their adaptability to different local ground conditions. Continued advancements in both DI and PVCO pipeline technologies have led to significant improvements in the design and functionality of segmented pipelines. To evaluate the effectiveness of their recent innovations, it is crucial to conduct the corresponding experimental testing and develop computational models.
Hence, this PhD study aims to comprehensively investigate the mechanical responses of modified jointed DI and newly designed segmented PVCO pipelines to earthquake-induced forces through a series of full-scale laboratory tests utilizing distributed fiber optic sensing (DFOS) technology for continuous strain measurement and conducting advanced three-dimensional (3D) finite element (FE) analyses.
A series of laboratory tests were conducted on the 203-mm (8-in) diameter DI pipeline with a restrained axial joint, three critical states have been identified: axial tension, deflection and biaxial tension (combined tension and bending). The behavior in each state is influenced by the orientation, quantity, and installation of locking segments in bell-spigot joints, leading to variations in joint stiffness, flexibility, and capacity. The analysis was then further extended to an innovative surrogate model using bushing connectors to replace the complex bell-spigot joint configurations, aligning well with expected outcomes while significantly reducing simulation time. This is particularly beneficial for future soil-pipeline interaction studies at the system level.
Similar to DI pipelines, a series of bending tests was also conducted on the 160-mm (6-in) diameter PVCO pipeline. The pipeline employs a 'Fittom-Coupler' fitting, sealed with an Ethylene Propylene Diene Monomer (EPDM) rubber and polypropylene ring gasket to connect two spigots securely and ensure water tightness. The results highlighted that performance is primarily influenced by bending stresses, leading to deflection and axial sliding. Validated models incorporating anisotropic properties and seal materials helped in conducting sensitivity analyses on varying wall thicknesses and fitting designs. Pipeline failure modes are shown typically involve mechanical disconnection at the joints and also local buckling related to variations in wall thickness. Such buckling can be reduced by altering the length or local shape of the fitting.
Both segmented restrained DI pipes and PVCO pipes present unique advantages for seismic water infrastructure. DI pipes provide exceptional strength for high-load environments, whereas PVCO pipes, with thinner walls and enhanced circumferential strength allow greater deflection capability, suitable for areas requiring resilience to large deformations.
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Keywords
Segmented water pipelines , Ductile Iron (DI) pipe , Polyvinyl chloride-oriented PVCO pipe , Full-scale laboratory test , Distributed fiber optic sensing , Three-dimensional (3D) finite element (FE) analysis , Joint bushing connector surrogate model
Citation
Zhang, Q. 2024. Experimental testing and finite element analysis of segmented water pipeline. PhD Thesis, University College Cork.