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Hazard-Resistant Steel Pipeline Response to Large Fault Rupture
Abstract and Figures
To address well-documented lifeline system vulnerability to ground deformation, a new generation of hazard-resilient pipeline products have been developed. These systems require evaluation for extreme loading conditions before they are accepted as viable options for design in hazard-prone regions. Presented is an experimental evaluation of a steel pipeline with special structural inclusions designed to accommodate significant ground displacement while providing continual water conveyance for post-disaster response. In addition to material characterization, axial tension/compression, and four-point bending tests, the evaluation includes a large-scale fault rupture experiment with an 8.5-in. (216-mm) diameter, 30-ft (8.8-m) long pipeline buried in sand with wave features positioned at either side of a right-lateral, strike-slip fault crossing. System response was captured by pre/post-test surveys as well as 116 instruments. The pipeline accommodated 24 in. (600 mm) of relative fault movement, corresponding to 15.2 in. (390 mm) of axial compression, without leakage/rupture nor significant loss of cross-sectional conveyance capacity.
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Prior to the 2010–2011 Christchurch earthquake sequence in New Zealand, buried pipes were thought to be tested with respect to all expected significant loadings as specified by material standards, such as AS/NZS 1477 for PVC pipes. However, the amount of damage to pipe joints observed in the field led the authors to believe that adding an axial joint load to the tests already mandated would greatly enhance the seismic design of pipes. For this purpose, an experimental investigation was completed on diameter nominal (DN)225 mm PVC-U pipe joints to ascertain the serviceability and ultimate limit state allowable loads when a pipe joint is subjected to axial seismic-simulated actions. The experimental results were able to replicate reported pipe earthquake damage by incorporating forces simulating peak ground accelerations in both the horizontal and vertical directions in the testing and by subsequently deriving relevant formulae. This research suggests that the existing compliance pipe standards can be easily modified to better replicate the observed seismic pipe damage, and the derived formulae could be used to improve decision support system models used by buried infrastructure asset owners to provide better postdisaster functionality information on their pipelines. The formulae presented herein are first-order checks and do not account for ground strains, ground displacements, or tensile actions. However, the proposed approach allows simplistic multiscenario comparative analysis to be done with relative ease.
Recognizing the need to improve the resilience of water distribution networks, water providers are seeking new technologies to accommodate ground deformation associated with seismically induced fault rupture, landslides, liquefaction-induced lateral spreading and settlement, and ground movements caused by other natural hazards, construction, mining, and regional dewatering activities. Pipeline manufacturers have responded to the need for improved resilience with innovative products designed to respond to significant levels of ground deformation through the use of improved materials and jointing mechanisms. Typical pipeline design is predicated on limiting relative displacements at pipe joints, or between the pipeline and surrounding soil. The new pipeline systems provide the capacity for large axial movements and deflections at joints, thus allowing pipelines to change shape, while maintaining pressure and flow, in response to complex patterns of ground displacement. To accompany new technologies and changes in design approaches, experimental procedures are proposed that assess the performance of hazard-resilient pipeline technologies under extreme loading conditions. Recommendations are provided based on best practices developed from more than sixty full-scale tests performed on pipes of various material and joint characteristics. Focus is given to the fundamental mechanics of pipeline response to externally applied movement: axial extension/compression and bending/joint deflection. Experimental evidence confirms that soil-pipeline interaction under large ground deformation can be decomposed into mechanical response parallel and perpendicular to the pipeline longitudinal axis, providing an effective means of understanding performance and developing hazard-resilient designs. Experimental methodologies, limit state assessment, instrumentation and load apparatus design, methods for interpreting and quantifying results, and classification of performance with respect to developing seismic design standards for water and wastewater pipelines are highlighted. ABSTRACT Recognizing the need to improve the resilience of water distribution networks, water providers are seeking new technologies to accommodate ground deformation associated with seismically induced fault rupture, landslides, liquefaction-induced lateral spreading and settlement, and ground movements caused by other natural hazards, construction, mining, and regional dewatering activities. Pipeline manufacturers have responded to the need for improved resilience with innovative products designed to respond to significant levels of ground deformation through the use of improved materials and jointing mechanisms. Typical pipeline design is predicated on limiting relative displacements at pipe joints, or between the pipeline and surrounding soil. The new pipeline systems provide the capacity for large axial movements and deflections at joints, thus allowing pipelines to change shape, while maintaining pressure and flow, in response to complex patterns of ground displacement. To accompany new technologies and changes in design approaches, experimental procedures are proposed that assess the performance of hazard-resilient pipeline technologies under extreme loading conditions. Recommendations are provided based on best practices developed from more than sixty full-scale tests, performed on pipes of various material and joint characteristics, to evaluate the large deformation capacity of these hazard-resistant systems. Focus is given to the fundamental mechanics of pipeline response to externally applied movement: axial extension/compression and bending/joint deflection. Experimental evidence confirms that soil-pipeline interaction under large ground deformation can be decomposed into mechanical response parallel and perpendicular to the pipeline longitudinal axis. For water distribution pipelines, this decomposition provides an effective means of understanding performance and developing hazard-resilient designs. Experimental methodologies, limit state assessment, instrumentation and load apparatus design, methods for interpreting and quantifying results, and classification of performance with respect to developing seismic design standards for water and wastewater pipelines are highlighted.
The principal causes of earthquake-induced ground deformation are identified and their interaction with underground infrastructure, primarily pipelines and conduits, is described. The coupled forces normal and parallel to underground pipelines arising from earthquake-induced ground movement are evaluated, including a review of measured stresses on pipe surfaces during large-scale testing, evaluation of frictional forces related to soil-pipe interaction, and the resolution of interaction forces along and across pipelines. Methods for characterizing soil reaction to pipe lateral and vertical movements are presented. The maximum downward pipe force is only about one-third the maximum force determined with conventional bearing capacity equations, thus requiring changes in current analytical and design practice. The analytical results for pipeline response to strike-slip and normal fault rupture are shown to compare favorably with the results of both large-scale and centrifuge tests of soil-pipeline interaction simulating these types of severe ground deformation.
A methodology is presented to evaluate multi-directional force–displacement relationships for soil–pipeline interaction analysis and design. Large-scale tests of soil reaction to pipe lateral and uplift movement in dry and partially saturated sand are used to validate plane strain, finite element (FE) soil, and pipe continuum models. The FE models are then used to characterize force versus displacement performance for lateral, vertical upward, vertical downward, and oblique orientations of pipeline movement in soil. Using the force versus displacement relationships, the analytical results for pipeline response to strike-slip fault rupture are shown to compare favorably with the results of large-scale tests in which strike-slip fault movement was imposed on 250 and 400 mm diameter high-density polyethylene pipelines in partially saturated sand. Analytical results normalized with respect to maximum lateral force are provided on 360° plots to predict maximum pipe loads for any movement direction. The resulting methodology and dimensionless plots are applicable for underground pipelines and conduits at any depth, subjected to relative soil movement in any direction in dry or saturated and partially saturated medium to very dense sands.
The analysis of buried pipelines has conventionally been based on elastic theory. In the Netherlands, codes of practice embodying this approach were published in 1971 and 1973. However, when these codes were applied to pipeline crossings already in existence at the time of publication, several of them were found not to satisfy the requirements. Therefore the crossings in question were judged to be deficient in safety by dyke managers. In view of the character of the loads (imposed deformations due to differential settlement) it was expected that, by applying plastic theory, it could be shown that the actual loadbearing and deformation capacity of the pipelines are substantially greater than calculated with elastic analysis. The principal results of the research are reported in the present publication. The effect of the internal pressure on the flexural behavior is described, along with the effect of external loads such as earth pressure and bending upon the rupturing pressure. The various failure modes are discussed, and the limit values to be compiled with are indicated. The research has led to the development of a new design method, which is explained, and rules for practical application of the method are derived. The practical application possibilities for the new design method are considered and the principal conclusions summarized.
Prepared by the Task Committee on Buried Flexible (Steel) Pipe Load Stability Criteria and Design of Pipeline Division of ASCE. This manual provides appropriate analytical concepts to address the principles of buried steel pipe design and attempts to correct misusage of the 1958 Modified Iowa Formula. The most current work of Dr. Reynold K. Watkins and others is presented in this book to develop external loading design concepts. The goal of Buried Flexible Steel Pipe is to offer sound information on the structural design and analysis of buried steel pipe-for water and wastewater-consistent with the latest pipe/soil design concepts of the industry. In conjunction with the external design of the pipe/soil interaction, the manual addresses internal pressure design, vacuum and external fluid pressure analysis, and many other nonstandard conditions pipe designers will likely encounter. This manual will be valuable to students and professionals involved in pipe design and construction. © 2009 by the American Society of Civil Engineers. All Rights Reserved.
Pipeline susceptibility to ground deformation resulting from natural hazards, such as earthquake-induced surface rupture, lateral spreading and landslides, as well as construction related movements is well-documented. The present need to replace and retrofit existing infrastructure in high risk areas is being addressed through the introduction of a variety of hazard-resilient pipeline systems. This paper reports on a large-scale testing program to characterize the performance of a novel hazard-resilient pipeline structure under large deformation. The experiments were performed at Cornell University’s Geotechnical Lifelines Large-Scale Testing Facility and include tests to characterize the axial capacity of a geometric inclusion (or wave feature) for use in continuously welded steel transmission pipelines crossing fault zones. Results from the testing program show that the wave feature can accommodate significant levels of deformation without pipeline rupture or leakage while limiting loss of cross-sectional area and flow capacity.
The present paper offers an overview of available methodologies and provisions for the structural analysis and mechanical design of buried welded steel water pipelines subjected to earthquake action. Both transient (wave shaking) and permanent ground actions (from tectonic faults, soil subsidence, landslides and liquefaction-induced lateral spreading) are considered. In the first part of the paper, following a brief presentation of seismic hazards, modelling of the interacting pipeline-soil system is discussed, in terms of either simple analytical models or more rigorous finite elements, pin-pointing their main features. In the second part of the paper, pipeline resistance is outlined, with emphasis on the corresponding limit states. Possible mitigation measures for reducing seismic effects are also presented, and the possibility of employing gasketed joints in seismic areas is discussed. Finally, the above analysis methodologies and design provisions are applied in a design example of a buried steel water pipeline, located in an area with severe seismic action.
JFE Engineering has developed "Steel Pipe for Crossing Fault (hereinafter SPF)," which can absorb extremely large fault displacement in order to secure the seismic safety of water pipelines crossing faults. Installation of plural SPF deformation nodes (buckling pattern sections) in straight pipes before and after a fault enables control of the location and mode of deformation in the pipeline when absorbing fault displacement. This function makes it possible to maintain inner section of the pipe, and thereby maintain the water supply with no leakage, even in very large earthquakes with ground transformation of several meters around the fault plane.
A general classification for scale in geotechnical engineering is used to explore the modelling of large, geographically distributed systems and their response to geohazards. Both component and network performance are reviewed. With respect to components, prototype-scale experiments of underground pipeline response to abrupt ground deformation are described, including control of soil properties, soil-pipeline interaction, and performance of high-density polyethylene pipelines. Direct shear (DS) apparatus size is shown to have a significant effect on DS strength, and the most reliable DS device is identified from comparative tests with different equipment. Mohr-Coulomb strength parameters for partially saturated sand are developed from DS test data and applied in finite element simulations of soil-pipeline interaction that show excellent agreement with prototype-scale experimental results. Apparent cohesion measured during shear failure of partially saturated sand is caused by suction-induced dilatancy. With respect to networks, the modelling of liquefaction effects on the San Francisco water supply is described, and a case history of its successful application during the Loma Prieta earthquake is presented. The systematic analysis of pipeline repair records after the Northridge earthquake is used to identify zones of potential ground failure, and correlate pipeline damage rates with strong ground motion. Hydraulic network analyses are described for the seismic performance of the Los Angeles water supply, with practical applications for emergency response. The effects of Hurricane Katrina are reviewed with respect to the New Orleans hurricane protection system, Gulf of Mexico oil and gas production, and interaction between electric power and liquid fuel delivery systems. The sustainability of the Mississippi delta is discussed with regard to flood control, maintenance of wetlands and barrier islands, and catastrophic change in the course of the Mississippi River.
Direct Tension and Cyclic Testing of JFE SPF Wave Feature
- B A Berger
- B P Wham
- T D O'rourke
- H Stewart
Berger, B.A., Wham, B.P., O'Rourke, T.D., Stewart, H. (2018). Direct Tension and Cyclic Testing
of JFE SPF Wave Feature, Ithaca, NY: Cornell University. Available.
Large-Scale Testing of JFE Steel Pipe Crossing Faults: Testing of SPF Wave Feature to Resist Fault Rupture
- B P Wham
- T D O'rourke
- H E Stewart
- T K Bond
- C Pariya-Ekkasut
Wham, B.P., O'Rourke, T.D., Stewart, H.E., Bond, T.K., & Pariya-Ekkasut, C. (2016). Large-Scale Testing of JFE Steel Pipe Crossing Faults: Testing of SPF Wave Feature to Resist
Fault Rupture. Ithaca, NY: Cornell University.
Standard Test Methods for Tension Testing of Metallic Materials
- ASTM International
Rolled Steel for General Structure
- Japanese Standards Association
Japanese Standards Association. (2015). "Rolled Steel for General Structure," JIS G 3010, Aug.
2015.