TRB Publications Index

Structural Failure Characteristics of Operational Pipeline Tunnel Adjacent to Pressurized Karst Cave

Wed, 18 Feb 2026 08:50:40 GMT

Internal pressure surges in karst caves from rainfall and groundwater fluctuations critically affect adjacent tunnel stability. This study first analyzes water inrush mechanisms from pressurized karst caves and lining-defect/karst-cave distributions. Then it examines contact pressure, maximum principal stress, mechanical responses, and deformation-failure characteristics as cave pressure increases at three positions (vault, left arch waist, left sidewall) using numerical simulation and model tests. Results show that cave pressurization markedly increases nearby contact pressure, with location effects ordered: vault > left arch waist > left sidewall. For vault or left-arch-waist positions, axial-force distribution nonuniformity increases with cave pressure. Conversely, left-sidewall locations show fluctuating uniformity in axial-force distribution. Under all three working conditions, the inner side of the lining adjacent to the karst cave is subjected to significant positive bending moments, while both sides experience negative bending moments. The structural deformation patterns under the three working conditions are generally consistent, with the deformation rate being the fastest at locations adjacent to the karst cave, where abrupt changes occur before structural instability. For vault or left arch waist positions, tensile cracks tend to develop on the inner surface of the lining adjacent to the cave. For left-sidewall positions, the critical water pressure for sidewall and invert failure is the lowest because of the combined action of three factors: the sidewall simultaneously bearing compression and tension, stress concentration at the sharp corner transition, and the invert being in an eccentric compression state.

Consensus Study Report: Less Troubled Waters: Transportation as a Source of Oil in the Sea

Fri, 26 Jul 2024 09:22:39 GMT

This article focuses on several transportation-specific contributors to oil in the sea including commercial vessels, recreational vessels, aircraft fuel jettison, and spills from oil and gas transportation. The article is based on a 2022 consensus study, Oil in the Sea IV: Inputs, Fates, and Effects. The study makes recommendations for improvement in oil-spill science, prevention, and mitigation of the impact of harmful discharges on the environment. The study concludes that scientific, regulatory, and production advances since the 2010 Deepwater Horizon disaster have spurred significant reductions in harmful releases from tankers, pipelines, and other transportation-related sources.

Ensuring Timely Pipeline Shutdowns in Emergencies: When to Install Rupture Mitigation Valves

Tue, 20 Feb 2024 14:55:20 GMT

As of April 2022, the Pipeline and Hazardous Materials Safety Administration (PHMSA) requires installation of rupture mitigation valves (RMVs) on newly constructed and replaced segments of hazardous liquid and gas transmission pipelines. This study assesses regulatory standards and criteria for deciding when automatic and remote-control shutoff valves (i.e., RMVs) should be installed on existing pipelines in high consequence areas. The report includes coverage of pipeline incidents, an overview of the regulatory framework, and criteria for making decisions for when to install valves on existing pipelines. Lastly, observations about the current regulatory direction and guidance are provided to pipeline operators for deciding when to install RMVs on existing pipelines and for inspectors to verify that all obligations for deliberate and informed decisions are being met. Conclusions based on this assessment are presented along with recommendations for strengthening the guidance provided and verification methods used for ensuring sound decisions.

Dynamic Effect of Fluid–Structure Interaction and Modal Analysis of Crude–Pipeline Interaction System Considering the Fluctuating Pressure of Medium

Mon, 24 Jul 2023 16:36:48 GMT

This work explored the fluid–structure interaction (FSI) effect of crude oil and pipeline and the vibration characteristics of the pipe–crude oil structural system. A finite element computational analysis theory and corresponding simulation method were proposed for crude oil pipelines considering the FSI effect. Meanwhile, the spring model of the FSI interface between crude oil and pipeline was proposed. The experimental simulation and neural network were adopted to obtain the flow-excited pulsation pressure (FEPP), and the kinetic equations of the pipe–crude oil FSI were analyzed. The finite element computation (FEC) model for pipe–crude oil bi-directional FSI dynamics was established, which was composed of five support span lengths and four pipe liquid levels and can provide five different crude oil fluid velocities. One hundred orthogonal simulation test conditions were designed. In addition, the displacement response and acceleration response under FSI of the pipe wall were calculated, and the first six orders of inherent frequencies and main vibration patterns of the FEC model were analyzed. The results revealed that the dynamic effect of FSI between the crude oil transport medium and pipeline was complex and was influenced by the length of the pipeline crossing section, medium flow velocity, difference of liquid surface height, and displacement response. The acceleration response possessed prominent vibration decay characteristics, and the response peak in the same condition was about 8.2 times larger than that of the steady-flow state response. Therefore, the effect changed the inherent frequency and vibration pattern of the pipeline, to which the engineering design should pay sufficient attention.

Numerical Investigation of the Strain Characteristics of a Natural Gas Transportation Pipeline Crossing Tunnel

Fri, 04 Nov 2022 09:08:30 GMT

To ensure the safe operation of a natural gas transportation pipeline (NGTP) crossing tunnel, a model is established to analyze the strain characteristics. Some factors affecting the strain are considered in this paper. The results show that the strain failure of a NGTP crossing tunnel may occur in the two elbows of the NGTP located at the tunnel entrance and the position in contact with the fixed pipe clamp near the tunnel entrance. At the same time, the strain of the NGTP crossing tunnel is obviously affected by the temperature change of natural gas. So, the temperature change should be controlled within 8 K in the actual operation process. The wall thickness, the length of the NGTP, and the slope angle of the crossing tunnel are also main factors to affect the strain of the NGTP crossing tunnel, while the operation pressure and mountain slope angle have little effect when the operation pressure is 6–11?MPa. The maximum value of Mises equivalent strain is also obviously affected by the pipe diameter when it is more than 273?mm. Meanwhile, a prediction model for the maximum value of Mises equivalent strain is also established by the nonlinear fitting method and the deviation is within ±15% between the calculations and simulation results. The above conclusions will provide a theoretical basis and data support for the safe operation and design of NGTP crossing tunnels.

Case Study of the Largest Concrete Earth Pressure Balance Pipe-Jacking Project in the World

Wed, 09 Mar 2022 12:12:08 GMT

Pipe jacking has been the dominant trenchless technology for constructing small (<2?m) to medium-diameter (<4?m) tunnels. Uncertainties and construction difficulties increase significantly when the diameter of the tunnel exceeds 4?m. This paper presents a case study of the largest concrete pipe-jacking tunnel project in the world, the sewerage tunnel along Jinshan Lake, Zhenjiang, China. In this project, an underwater tunnel with a diameter of 4.67?m was constructed by the earth pressure balance (EPB) pipe-jacking method. The case study reports project background, and geological and hydrogeology conditions. The key techniques such as the selection of pipe-jacking machine, jacking force estimation and control, design of intermediate jacking station, grouting process control, launching, and reception of the tunnel boring machine, trajectory control of pipe jacking, and ventilation and gas monitoring during the construction period were investigated and discussed. Furthermore, to overcome the technical difficulties associated with the oversized jacked tunnel, the corresponding countermeasures were adopted point by point, so that the safety of the whole project could be guaranteed. This study filled the knowledge gap of technical know-how for large-diameter (over 4.5?m) pipe-jacking tunnel and is expected to provide practical guide for future large-diameter pipe-jacking tunnels.

SafeOCS: Toward a Better Understanding of Safety Event Data

Tue, 11 Jan 2022 13:37:14 GMT

The SafeOCS Industry Safety Data (ISD) Program is a voluntary confidential reporting program that collects and analyzes data to advance safety in oil and gas operations on the Outer Continental Shelf. The program was developed under a partnership between a federal regulator, the Bureau of Safety and Environmental Enforcement, and a principal federal statistical agency, the Bureau of Transportation Statistics, and phase I was conducted in collaboration with nine early implementer companies. This paper reports on development of the full program following the completion of phase I, including the unique processes developed to capture, transform, aggregate, and analyze safety event data on an industry-wide basis for companies working in the Gulf of Mexico. The aggregated data, including offshore transportation events, are then utilized to identify industry-wide trends for advancing safety in oil and gas operations.

Analysis of Ultimate Bearing Capacity and Parameters of Steel Support Cutting Pipe Roofing Structure

Tue, 14 Dec 2021 19:51:33 GMT

A new pipe-roof construction method, the steel support cutting pipe method (SSCP), was proposed to improve the construction security and accuracy of pipe jacking as well as underground space usage. The pipe-roof method is one of the underground excavation methods which push multiple steel pipes into the soil, then connect the steel pipes horizontally to form a whole. The proposed structure’s failure mode and force characteristics were determined through theoretical analysis, and then its ultimate bearing capacity and influencing parameters were analyzed through laboratory experiments and numerical simulation. The research results show that the structure’s bearing capacity depends on the steel pipe’s buckling load; the structure’s failure mode is a result of the steel pipe’s buckling. The ultimate bearing capacity of the pipe-roof structure first increases and then decreases with the increase of the steel pipe chord height ratio. The ultimate bearing capacity reaches the maximum when the ratio is 0.33. In addition, the structure’s ultimate bearing capacity is positively related to the steel pipe wall thickness and the pipe section’s length. This can be obtained from the relationship curve showing that the steel pipe wall thickness should be selected according to the engineering requirements and that the pipe section’s length is preferably 2.3 times the diameter of the steel pipe in the construction design.

Numerical Evaluation of Buried Medium Density Polyethylene Pipelines Subjected to Axial Ground Movement

Thu, 04 Feb 2021 10:57:26 GMT

Buried pipeline network forms an indispensable infrastructure that is extensively used for transporting and distributing natural gas and liquid. One of the major problems associated with the performance of this network is related to the deformation of pipelines in areas prone to ground movement. The maximum axial force on the pipeline subjected to axial ground movement is commonly calculated using a design equation developed without proper consideration of soil-pipe interaction. The authors’ recent work revealed that soil-pipe interaction significantly contributes to the axial pullout load, particularly for flexible pipes. This paper presents the results of numerical study conducted to explore the mechanics of soil-pipe interaction that could not be measured during tests. Particularly, the effect of rate-dependent interface behavior of the polyethylene pipe material on pulling resistance could not be measured during the tests. The FE model is developed through validation with full-scale laboratory test results performed at Memorial University of Newfoundland. The study reveals that FE analysis with interface friction angles of 75% to 90% of the peak friction angle of surrounding soil can successfully simulate ground movements of various rates. Based on the results obtained, a simplified equation is proposed to estimate the mobilized frictional lengths for pipeline performance assessment.

Analysis of Emergency Incidents Regarding Natural Gas Distribution Pipelines

Thu, 04 Feb 2021 10:54:40 GMT

Natural gas distribution infrastructure is critical to the daily operation of society. To improve the safety of gas distribution systems, it is vital to understand the combination and interaction of factors that contribute to the severity of incidents involving natural gas distribution pipelines. Hence, this study analyzes five years of PHMSA data using discrete outcome modeling to identify specific factors and their effects on the severity of emergency incidents involving gas distribution systems. Three discrete outcome categories were created based on both the cost of the incident and quantity of gas released to be used as the dependent variable. A multinomial logit model was fitted to the data with several independent variables. Excavation damage, explosion, incorrect operation, and public properties increased the severity of pipeline incidents. Variables such as facility shutdowns, steel pipes, and daylight decreased the severity of the incident. This study serves as a basis for introducing econometric discrete choice modeling to utility researchers, where more findings can be revealed and understood.

Safety Regulation for Small LPG Distribution Systems

Wed, 19 Aug 2020 13:48:28 GMT

This report examines the regulatory framework for gas pipeline systems that transport propane and other types of liquefied petroleum gas (LPG) for service to 100 or fewer customers. Most of the more than 12 million households and businesses that use LPG are on single-customer systems but a small number—between 3,800 and 5,800—are served by multi-user systems. These systems are potentially subject to federal safety regulations administered by the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA). In response to a congressional request under the direction of PHMSA, the report reviews the safety regulatory framework that applies to small multi-user LPG pipeline systems, reviews what is known about their safety performance, and provides recommendations on ways to make their regulatory requirements more risk-based. The committee recommends that PHMSA develop more effective means of identifying small, multi-user LPG systems and to ensure they are inspected and their risks are better understood. The report recommends actions intended to allow more uniform interpretations of regulatory terms, the collection of condition and safety information on small LPG systems, and state regulators to seek permission from PHMSA to allow some small systems to opt out of certain federal regulatory requirements that are not applicable to their risks.

Oil Sands, Pipelines and Fracking: Exploring Citizen Acceptance of Unconventional Fossil Fuels in Canada

Fri, 01 Mar 2019 15:51:21 GMT

Because the transportation sector is still 95% powered by fossil fuels, it will be strongly affected by the development of unconventional fossil fuel resources. The authors use a nationally representative survey sample of the Canadian population (n=1,407) to examine citizen acceptance of five prominent unconventional fossil fuel developments: oil sands, Northern Gateway Pipeline, TransMountain Pipeline, Energy East Pipeline, and hydraulic fracturing. Across Canada, oil sands and pipeline developments tend to have less acceptance than renewable energy and conventional oil, but more acceptance than nuclear and coal. Among Canadian regions, acceptance for unconventional fossil fuel developments is consistently higher among respondents in Alberta (the province where most fossil fuel development occurs), where respondents are more likely to perceive economic benefits and less likely to perceive environmental and social costs. Opposition tends to be higher among respondents in British Columbia and Quebec. Acceptance levels are similar for oil sands and oil sands pipelines within all Canadian regions, while hydraulic fracturing has significantly lower acceptance in each region. Regression analyses indicate consistent patterns of acceptance across the full sample: opposition is predicted by higher biospheric and altruistic values and environmental concern, and support is predicted by higher egoistic and traditional values and higher trust in oil and gas companies. Results provide insights to policymakers and stakeholders, including the strong regional differences in development acceptance, and how citizens perceive oil sands related projects differently from hydraulic fracturing projects.

Rehabilitated Culvert Structural Design and Hydraulic Enhancement Method

Fri, 01 Mar 2019 15:51:20 GMT

The purpose of this paper is to introduce and discuss solutions for culvert lining with special consideration given to the structural elements and the hydraulic inlet conditions. There are many lining solutions available to the industry today and it is essential to differentiate the solutions that meet highway design criteria. Headwater increases should be a primary concern when modeling culvert liner flow but many times the design overlooks effects the inlet has on entire system and only the properties of the pipe liner itself are considered. The purpose of this research is to show that improving the inlet conditions can be highly beneficial and can offset any concerns for the liner as a viable solution to a failing culvert. Utilizing software and other industry resources, this study analyzed the liner system and proved both structural and hydraulic sufficiency for a 63 inch outside diameter liner inside of a 72 inch host pipe and the addition of a Hydro-Bell inlet device. The structural modeling showed that the solid wall High Density Polyethylene (HDPE) pipe met the requirements of modern highway standards. Hydraulic modeling showed that even though the liner has a smaller internal diameter, it still can meet drainage requirements for the site.

Dynamic, Three Dimensional Response of a Corrugated Steel Arch Culvert

Fri, 01 Mar 2019 15:51:20 GMT

A metal arch culvert has been instrumented with optical fibres and tested under static and dynamic vehicle loads. The axis of the 2.75 m span semi-circular culvert was skewed at 45 degrees from the centreline of the roadway overhead. Distributed strain profiles around the circumference were successfully captured by the static and dynamic optical fibre systems. Calculated distributions of live load thrust showed that peak thrusts were obtained near the crown. The high magnitudes of moment compared to thrust suggest that for this shallow buried culvert, bending moments are likely as important as thrust forces and it would be preferable if they were not routinely neglected in the design standards. Dynamic testing led to thrusts and moments under the front wheels of the test truck that were from 1.07 to 1.85 times larger than those from the rear wheels. Measurements became noisier and more data were lost with increase in speed. The pavement led to a 10% decrease in thrusts in the static tests, but this influence became small as the speed increased, until velocity of 30 km/h. While the pavement had little influence on thrusts, it had a large impact on bending moments. In both static and dynamic tests, bending moments for wheels on the road pavement reduced by approximately 30%. Thrust and moment envelopes were prepared, to provided peak (most positive and least negative) values around the circumference. Envelope plots demonstrated that many locations near the crown experienced thrusts higher than those at the springlines. The development of the culvert response envelopes was greatly facilitated by the use of optic fibres (many strain gauges would be required to obtain this kind of data).

Effect of Sliplining on Behavior of Corroded Corrugated Steel Pipes under Loading

Fri, 01 Mar 2019 15:51:19 GMT

Culverts and pipes installed under roadways several decades ago are reaching the end of their service life. Excavation and replacement of these buried structures will cause disruption to their service and require significant funding. Trenchless methods (e.g., sliplining) have been increasingly used to rehabilitate deteriorated buried structures (e.g., corroded steel pipes). Sliplining involves placement of a new pipe liner inside an existing deteriorated pipe and grouting of the space between them. In this experimental study, parallel-plate loading tests were carried out to evaluate the effect of sliplining on the behavior of corrugated steel pipes with different degrees of corrosion. The nominal diameters of corrugated steel pipes and polyvinyl chloride liner were 305 and 254 mm, respectively. This study investigated three different degrees of steel pipe corrosion (0%, 50%, and 90%). A low-strength, normal density grout was used to fill the space between the steel pipe and the liner. The pipes without and with sliplining were tested for their load-carrying capacity, stiffness, vertical and horizontal diameter changes, and average strains and curvatures. The experimental results show that prior to sliplining, the steel pipe with 90% corrosion had a higher stiffness than that with 50% corrosion at a higher applied load. After sliplining, however, the steel pipe with 50% corrosion had a higher stiffness than the pipe with 90% corrosion. Sliplining increased the load-carrying capacity and stiffness of the pipe. The location of the liner relative to the existing pipe had a minor effect on the behavior of the sliplined steel pipes.