Geohazards and Pipelines: State-of-the-Art Design Using Experimental, Numerical and Analytical Methodologies

By Spyros A. A. Karamanos

This book presents state-of-the-art methodologies for the design and analysis of buried steel pipelines subjected to severe ground-induced action, including tectonic (quasi-static) effects, slope movements (landslides), liquefaction-induced actions or excavation-induced settlements. The text is an amended version of the final deliverables of the GIPIPE project, sponsored by the European Commission (Research Fund for Coal and Steel programme, 2011-2014).
Geohazards and Pipelines presents an integrated investigation of this subject, using advanced and innovative experimental techniques, high-performance numerical simulations and novel analytical methodologies, which account for the particularities of buried steel pipelines with an emphasis on soil-pipeline interaction.
Geohazards and Pipelines will be of use to professionals working in the field of pipeline engineering, including design consultants and industrial practitioners involved in projects related to pipeline infrastructure. Structural engineers, mechanical engineers, geotechnical engineers, geologists and seismologists may also find this book of interest, as may graduate students and researchers in these areas.

• Language: English
• Publisher: Springer
• Release date: Oct 31, 2020
• ISBN: 9783030498924

Book preview

Part IIntroductory Concepts of Pipeline Behavior in Geohazard Areas

© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021

S. A. Karamanos et al. (eds.)Geohazards and Pipelineshttps://doi.org/10.1007/978-3-030-49892-4_1

1. Introduction

Spyros A. Karamanos¹  , Gert J. Dijkstra², ³  , Arnold M. Gresnigt⁴, ⁵  , Wouter Huinen⁶ and Kyriaki A. Georgiadi-Stefanidi¹

(1)

Department of Mechanical Engineering, University of Thessaly, 38334 Volos, Greece

(2)

GJ-D Consult, 3155 BV Maasland, The Netherlands

(3)

Tebodin Consultants & Engineers BV (Bilfinger Tebodin), 3122 HD Schiedam, The Netherlands

(4)

Faculty of Civil Engineering, Delft University of Technology, 2628 CN Delft, The Netherlands

(5)

Gresnigt Consultancy, 2651 XT Berkel en Rodenrijs, The Netherlands

(6)

Bilfinger Tebodin Netherland B.V., 3122 HD Schiedam, The Netherlands

Spyros A. Karamanos (Corresponding author)

Email: [e-mail]

Gert J. Dijkstra

Email: [e-mail]

Arnold M. Gresnigt

Email: [e-mail]

Abstract

This introductory chapter presents the main scope of this book and the relevant background. The main objective is the development of guidelines for the analysis and design of buried steel pipelines under ground-induced actions, to be used by researchers, engineers and code-drafting committees. The GIPIPE project is summarized and an outline of the main results is offered. Finally, the last part of the chapter describes pipeline damages due to major seismic and landslide events since the early twentieth century, pin-pointing the influence of ground-induced actions on pipeline structural integrity.

1.1 Scope, Background and Objective

Steel buried pipeline networks are of paramount importance for the international economy. A possible threat to these networks is the occurrence of severe ground–induced deformations, resulting from landslides and liquefaction of soils or seismic activity. These large deformations may cause high inelastic strains in the pipe wall and, ultimately, lead to rupture and interruption of delivery.

The present book focuses on the structural safety of buried butt-welded continuous carbon steel pipelines under severe ground-induced deformations. It refers mainly to the design of new buried steel pipelines in areas where ground displacements and deformations may occur, resulting from seismic action or landslides. Nevertheless, it can also be employed for the seismic assessment of existing pipelines. The guidelines in the present book constitute the final deliverable of the GIPIPE project, sponsored by the European Commission. The content of the book can be regarded as an integration of results from the GIPIPE project with existing standards and literature on the mechanical design of buried pipelines in geohazard areas. More specifically, the present book is aimed at defining the topic and the relevant scientific background, presenting the important design issues related to the topic of Geohazards and Pipelines and providing guidance/methods to solve the problem using efficient numerical and analytical methodologies, validated by novel experimental testing.

The guidelines of this book should be used cautiously for non-metallic pipelines. In particular, the basic principles for predicting ground-induced actions on the pipeline, consisting a procedure referred to as strain demand, can be used for pipes of different material. However, the ultimate strength and deformation capacity of non-metallic pipelines can be quite different. In addition, the present guidelines do not refer to above-ground industrial piping systems in power plants, or in chemical/petrochemical industries. The guidelines focus mainly on continuous butt welded steel pipeline applications (gas, oil and water pipelines). They are not directly applicable to welded pipelines with lap joints, used extensively in the United States for water transmission. The structural response and deformation capacity of lap welded joints require special treatment, which is not part of the present book. The reader interested in this topic is referred to the recent works by Keil et al. (2018) and Chatzopoulou et al. (2018). In addition, the case of segmental pipelines, usually composed by pipeline segments connected with gasketed joints, also used extensively for water transmission, requires special attention, which is out of the scope of the present book. Finally, this book does not contain specific guidance on the retrofit of existing pipeline systems; nevertheless, parts of the book and the methodologies presented may contain useful information towards this purpose.

The present European standards on design of buried pipelines, such as EN 1594 and EN 14161, provide only limited information for the design of pipeline systems against large ground deformations, e.g. resulting from seismic faults or landslides. The design methods and design criteria in these standards do not fully cover the calculation of forces, stresses and strains in buried pipelines when these large ground-induced deformations occur and the required pipeline strength to sustain these actions. Such information can be also found in the 2006 edition of EN 1998-4, the European standard for seismic design of tanks, silos and pipelines, but the proposed design framework in that standard requires significant enhancement.

The GIPIPE research project was aimed at fulfilling this gap, including a study of the relevant international standards and guidelines, with emphasis on pipe-soil interaction of buried pipelines. The outcome of this project is summarized in Part II and comprises results from extensive analyses of pipeline components undergoing large ground-induced deformations, including pipe-soil interaction. The GIPIPE project included extensive testing and related numerical analyses of pipelines, enhancing current knowledge on the response of buried pipelines and pipe-soil interaction when the pipe is subjected to severe ground-induced deformations. The testing program within the GIPIPE program was meant for validation of numerical models (rigorous and more simplified), and the main experimental results of this testing program are outlined in Chap. 4 of this book. In addition, analytical tools are developed that enable pipeline analysis and design in a simple and efficient form.

The present book, as outcome of the GIPIPE project, is aiming at providing guidance for researchers and practicing engineers dealing with buried steel pipelines. In particular, this book provides:

identification of critical steps and parameters in the design of buried steel pipelines under severe ground-induced deformation;

recommendations for developing efficient pipe-soil interaction models;

calculation examples for pipelines under seismic fault and/or landslide, both with advanced and with simple and efficient calculation models;

information for the calibration and validation of numerical models developed within the GIPIPE project, using the results of laboratory experiments and field testing in pipe segments, subjected to large ground-induced deformations;

definition of structural resistance (ultimate limit states) of pipeline components, i.e. straight pipe segments and pipe bends.

The ultimate goal of the GIPIPE design guidelines was to assure that buried steel pipelines, fulfilling the preset requirements, after the occurrence of a severe ground-induced deformation will remain operational without loss of pressure containment.

In pipeline design, two limit states need to be considered: serviceability and ultimate. Serviceability refers to the operation of the pipeline after a seismic event (limitations on ovalization and local buckling), while the ultimate limit states refer to loss of pressure containment, which is associated with rupture of the pipe wall.

1.2 Description of the GIPIPE Project (2011–2014)

The GIPIPE project has been a pioneering research project, sponsored by the European Commission, within the Research Fund of Coal and Steel (RFCS) in the area of steel pipeline safety for transportation of energy resources. The project was entitled Safety of Buried Steel Pipelines Under Ground-Induced Deformations. It has been coordinated by the University of Thessaly, Volos, Greece. It started in July 2011 and finished in June 2014 (36-month duration). The project combined experimental, numerical and analytical tools to perform high-level research on the inter-disciplinary area of buried steel pipelines under severe ground-induced actions. Extensive experimental and numerical work has been conducted, with main purpose to investigate the interaction between the pipe and the surrounding soil; this is the key issue for determining actions on the steel pipeline in a reliable manner.

The GIPIPE consortium has been composed by the following partners:

University of Thessaly (Volos, Greece) [coordinator]

Centro Sviluppo Materiali S.p.A. (Rome, Italy)

Delft University of Technology (Delft, The Netherlands)

National Technical University of Athens (Athens, Greece)

Corinth Pipeworks S.A. (Thisvi, Greece)

Tebodin Consultants and Engineers B.V. (Bilfinger-Tebodin, Schiedam, The Netherlands).

The project combined geotechnical engineering concepts and structural design principles with mechanical and pipeline engineering practice and was aimed at developing design guidelines/recommendations for safeguarding structural integrity of buried welded steel pipelines subjected to severe ground-induced actions. More specifically, permanent ground-induced actions were considered, such as fault motion, landslides or liquefaction-induced lateral spreading. The proposed guidelines improve and extend current design practice, considering the particularities of steel pipeline behaviour, with emphasis on soil-pipe interaction. The following targets have been achieved within the GIPIPE project:

Critical evaluation of current design practice towards identification of specific needs for developing pipeline provisions in geohazard areas.

Development of rigorous three-dimensional models for analyzing buried pipelines in cohesive and non-cohesive soils under permanent ground actions (faults, landslides, lateral spreading) with special emphasis on soil material modeling.

Performance of large-scale experiments, supported by small-scale tests, to determine pipeline mechanical behavior under various ground conditions, within the purpose of examining the interaction between the soil and the steel pipe.

Extensive parametric analyses for buried pipelines under ground-induced actions due to fault action and landslide action.

Proposal of well-calibrated analytical methodologies for the simple and efficient stress analysis of buried pipelines, to be used for design purposes.

Presentation of a set of guidelines for buried pipeline design against permanent ground-induced actions, which summarizes existing knowledge and incorporates all results from the present research program.

Dissemination of GIPIPE results and interaction with the pipeline engineering community, through a dedicated workshop, organized by the project consortium (June 2014, Delft, The Netherlands).

More information on the project can be found in the final report of the project (Vazouras et al. 2015). Three major points that characterize this research program should be underlined:

1.

Most of the research work on steel pipelines and piping within the Research Fund for Coal and Steel program has been directed towards pipeline resistance, mainly failure against fracture referred to as strain capacity. The present work is the first project that focuses on pipeline strain demand, which is an equally important issue towards reliable and safe pipeline design.

2.

The present work refers to extreme loading conditions for the steel pipeline, associated with large deformation and strains well into the inelastic range of the steel material. Therefore, the results of the GIPIPE project should be considered within a strain-based design framework. Furthermore, it should be underlined that traditional analytical tools for pipeline stress analysis, based on the concept of stress-based design (developed mainly for pipeline design under pressure containment), may not be applicable in pipeline design against geohazards.

3.

The particularities of buried pipeline performance have been taken into account. In particular, one has to consider that:

loss of containment is the major limit state and refers to a severe local damage situation. This is in contrast with building structures, where local damage may not necessarily be catastrophic due to the possibility of redistribution of internal forces, if the structure is designed for this possibility;

for the particular case of seismic action in welded steel pipelines, due to soil embedment, permanent ground-induced actions are the primary actions in pipeline design. Transient (wave shaking) phenomena are much less important than permanent ground-induced actions and may be given less attention.

The main results of the GIPIPE project can be summarized as follows:

Experimental work has been conducted for supporting numerical models towards accurate predictions of strain demand in the pipeline. A good comparison has been achieved between test results and numerical predictions.

Experimental results offered a substantial contribution towards understanding soil-pipe interaction (axial and transverse direction). Distribution of pipeline pressure on the surrounding soil is measured.

Test results have also indicated that the formation of a local buckle in pressurized pipelines, in several instances, may be associated with loss of containment, given the fact that other detrimental factors (e.g. girth welds, unfavorable material properties) are also present.

Important results have been obtained for curved pipeline components (referred to as bends or elbows); their unique structural response under bending and, in particular, their increased flexibility may allow their use as mitigation devices, but require a detailed strain analysis to avoid failure of the elbow itself.

Simplified methodologies that employ pipe finite elements have been employed and compared successfully with more rigorous finite element models. Furthermore, simplified analytical methodologies, which can be used for preliminary pipeline design against geohazards, have also been proposed.

Finally, the design guidelines/recommendations developed can be used by Code Drafting Committees, for the amendment of existing design standards (e.g. EN 1998-4 for pipeline seismic design).

The results and deliverables of GIPIPE are both novel and unique, leading to

construction of innovative state-of-the-art devices for experimental simulation of buried pipeline response;

development and validation of rigorous and simplified models, capable of describing large permanent deformations of buried pipelines with a good level of accuracy;

better understanding of soil-pipe interaction under severe ground-induced actions;

significant improvement of the state-of-the-art of pipeline design in geohazard areas.

The entire GIPIPE work is reported in the final report of the project (Vazouras et al. 2015), available in digital form in the website of the Publications Office of the EU, and the corresponding deliverables, which are available upon request to the project coordinator. Furthermore, a significant number of relevant publications in international scientific journals and conferences have been presented and constitute a well-documented background for Code Drafting Committees, for developing or updating standards and guidelines towards safer and more reliable pipeline design against geohazards.

1.3 Overview of Ground Movement Induced Damage to Pipelines

The reference list at the end of this Chapter contains a brief database of literature concerning the share of ground movement induced damage to pipelines in the incident frequency (Porter et al. 2004; Savigny et al. 2005; Bolt 2006; NEB 2009; Davis et al. 2011; EGIG 2018; Girgin and Krausmann 2016; Goodfellow et al. 2018). Some examples of pipeline incident data (PID) and ground movement induced damage to buried pipelines are also provided in the present section.

1.3.1 Share of Ground Movement Induced Damage to Buried Pipelines

In this section, an overview of the share of ground movement induced damage to pipelines in different parts of the world is provided. According to the 10th Report of the European Gas Pipeline Incident Data Group (EGIG 2018), ground movement induced damage attributes approximately 15% to the total amount of incidents for the period 2007–2016 and respectively, 8% for the period 1970–2013. The primary failure frequency due to ground movement is reported to be more or less constant over the years: its value was approximately 0.026 per 1000 km.year over the period 1970–2016, with a small peak in the period 2012–2016 at 0.031 per 1000 km.year. Furthermore, ground movement is the second leading cause for the failure mode of rupture of the pipeline, after external interference.

There are many types of Ground Movement incidents and Table 1.1 presents the distribution of the different sub-causes in the category of ground movement that cause a pipeline incident, according to the recent EGIG report (EGIG 2018). Based on this data, it is clear that the vast majority of the ground movement incidents are caused by landslides, especially in the recent 10 years.

Table 1.1

Distribution of the sub-causes of ground movement in Western Europe for 1970–2016 and 2007–2016 (EGIG 2018)

In the United Kingdom, ground-induced damage in pipelines attributes approximately 4% to the total amount of incidents, according to the UKOPA Pipeline Product Loss Incidents and Faults Report for the period 1962–2016 (Goodfellow et al. 2018). It should be noted though, that the UK is not a seismic country and this justifies the low percent of incidents due to ground movement. Nevertheless, ground movement is the second leading cause related to pipeline rupture (full bore). The natural gas transmission data for the period 1984–2001 reported by the US Department of Transportation (US DOT) shows that ground movement induced damage accounted for 8.5% of the total amount of incidents (Porter et al. 2004). However, the property damage cost caused by ground movement induced damage is only exceeded by the costs caused by third party damage. From the above information, it can be concluded that, although in some parts of the world the pipeline incidents caused by ground movement represent a rather small percentage of the total amount of incidents, they are generally related to severe damage, associated with pipe-wall rupture, greater property damage costs and longer periods required for the restoration of the damaged infrastructure and the disrupted services, with respect to other types of hazard (Porter et al. 2004).

In other parts of the world, where pipelines are constructed in a more geologically active terrain, ground movement can be proved rather significant as far as pipeline incidents are concerned. The risk for a pipeline incident due to ground movement becomes greater if the specific characteristics of the difficult terrain are not appropriately taken into account during the pipeline design and construction stage. For example, data for a typical pipeline in the South American Andes indicate that ground movement may be the cause for 50% of the total amount of pipeline incidents, leading to an average failure frequency that exceeds 2.5 per 1000 km·yr, as reported by Savigny et al. (2005). This frequency is about two orders of magnitude greater than the corresponding frequency reported in Western Europe.

1.3.2 Examples of Ground Movement Induced Damage to Buried Pipelines

1.3.2.1 North American Earthquakes from 1900–1975

Table 1.2 offers a summary of various North American earthquakes that occurred in the 20th century, up to 1975, in terms of pipeline and cable damage. The data in this table are obtained by the relevant publication of O’ Rourke and McCaffrey (1984). In most instances, pipeline damage can be attributed directly to permanent ground movements. For example, the locations of cast iron water main breaks after the 1906 San Francisco earthquake show a strong correlation with the