scholarly journals Effects of Axial Relative Ground Movement on Small Diameter Polyethylene Piping in Loose Sand

2021 ◽  
Vol 6 (12) ◽  
pp. 168
Author(s):  
Auchib Reza ◽  
Ashutosh Sutra Dhar
Keyword(s):  
Distribution System ◽  
Design Method ◽  
Small Diameter ◽  
Friction Angle ◽  
Design Guidelines ◽  
Ground Movement ◽  
Loose Sand ◽  
Ground Movements ◽  
Rate Dependent ◽  
Pulling Force

Small diameter (42 mm) medium density polyethylene (MDPE) pipes are widely used in the gas distribution system in Canada and other countries. They are sometimes exposed to ground movements resulting from landslides or earthquakes. The current design guidelines for evaluating the pipes subjected to ground movement were developed for steel pipes of larger diameters and may not apply to flexible MDPE pipes. This paper evaluates 42 mm diameter MDPE pipes buried in loose sand under axial relative ground movement for developing a design method for the pipes. MDPE is a viscoelastic material; therefore, the behaviour of MDPE pipes exposed to landslides would depend on the rate of ground movements. In this research, full-scale laboratory tests were conducted to investigate the responses of buried pipes under various rates of relative axial displacement. Finite element modelling of the tests was used to interpret the observed behaviour using the continuum mechanics framework. The study revealed that the pulling force on the pipe depends on the rate of relative ground displacement (pulling rate). The nondimensional pulling force possessed a nonlinear relationship with the pulling rate. A rate-dependent interface friction angle could be used to calculate the maximum pulling forces using the conventional design guidelines for the pipes in loose sand. Based on the pulling force, the pipe wall strains can be estimated using the methods available for larger diameter pipes.

Use of Discrete Element Modeling to Capture the Effect of Backfill Particle Size on the Soil Restraints of Buried Pipelines Subjected to Lateral Ground Movement

2014 ◽  
Author(s):  
Sadana Dilrukshi ◽  
Dharma Wijewickreme
Keyword(s):  
Particle Size ◽  
Friction Angle ◽  
Discrete Element ◽  
Ground Movement ◽  
Scale Model ◽  
Discrete Element Modeling ◽  
Buried Pipelines ◽  
Ground Movements ◽  
Backfill Material ◽  
Ground Deformations

Geotechnical hazards can be a major cause of damage to pipelines, particularly as a result of unacceptable strains induced in buried pipelines due to permanent ground deformations. The common design philosophy in reducing soil restraint involves taking measures to effectively isolate the pipeline from the anticipated surrounding soil movements. One of the important engineering design considerations in this regard is the selection of suitable trench backfill material(s). Full-scale model tests have revealed that, in addition to the internal friction angle, coarseness of the backfill material is also an important parameter in controlling the lateral soil restraints on the pipes due to ground movements. It can be demonstrated that discrete element approach is suitable to study the effect of particle size on lateral soil loads of buried pipelines subjected to ground movement. This paper describes the outcome from DEM numerical modeling of the response of buried pipelines subjected to lateral ground movements, with a comparison of the findings with experimental results.

Integrity Management of Ground Movement Hazards

2016 ◽  
Author(s):  
Yong-Yi Wang ◽  
Don West ◽  
Douglas Dewar ◽  
Alex McKenzie-Johnson ◽  
Millan Sen
Keyword(s):  
Management Program ◽  
Ground Movement ◽  
Tensile Failure ◽  
Weld Strength ◽  
Factors Affecting ◽  
Ground Movements ◽  
Decision Points ◽  
Starting Point ◽  
Integrity Management ◽  
Girth Welds

Ground movements, such as landslides and subsidence/settlement, can pose serious threats to pipeline integrity. The consequence of these incidents can be severe. In the absence of systematic integrity management, preventing and predicting incidents related to ground movements can be difficult. A ground movement management program can reduce the potential of those incidents. Some basic concepts and terms relevant to the management of ground movement hazards are introduced first. A ground movement management program may involve a long segment of a pipeline that may have a threat of failure in unknown locations. Identifying such locations and understanding the potential magnitude of the ground movement is often the starting point of a management program. In other cases, management activities may start after an event is known to have occurred. A sample response process is shown to illustrate key considerations and decision points after the evidence of an event is discovered. Such a process can involve fitness-for-service (FFS) assessment when appropriate information is available. The framework and key elements of FFS assessment are explained, including safety factors on strain capacity. The use of FFS assessment is illustrated through the assessment of tensile failure mode. Assessment models are introduced, including key factors affecting the outcome of an assessment. The unique features of girth welds in vintage pipelines are highlighted because the management of such pipelines is a high priority in North America and perhaps in other parts of the worlds. Common practice and appropriate considerations in a pipeline replacement program in areas of potential ground movement are highlighted. It is advisable to replace pipes with pipes of similar strength and stiffness so the strains can be distributed as broadly as possible. The chemical composition of pipe steels and the mechanical properties of the pipes should be such that the possibility of HAZ softening and weld strength undermatching is minimized. In addition, the benefits and cost of using the workmanship flaw acceptance criteria of API 1104 or equivalent standards in making repair and cutout decisions of vintage pipelines should be evaluated against the possible use of FFS assessment procedures. FFS assessment provides a quantifiable performance target which is not available through the workmanship criteria. However, necessary inputs to perform FFS assessment may not be readily available. Ongoing work intended to address some of the gaps is briefly described.

Die Wertstrommethode in der Prozessindustrie*/The Value Stream Method in the process industry - Analysis of its shortcomings and recommendations for adaption

2017 ◽  
Vol 107 (04) ◽  
pp. 231-234
Author(s):  
K. Erlach ◽  
E. Sheehan ◽  
S. Hartleif
Keyword(s):  
Production Systems ◽  
Design Method ◽  
Design Guidelines ◽  
Process Industry ◽  
Joint Production ◽  
Industry Analysis ◽  
Process Industries ◽  
Good Industry ◽  
Value Stream ◽  
Different Characteristics

In der Stückgutindustrie lassen sich die acht Gestaltungsrichtlinien der Wertstrommethode nach Erlach hervorragend anwenden. In der Prozessindustrie weist die Produktion jedoch häufig andere Merkmale (beispielsweise eine Kuppelproduktion) auf, die neue Herausforderungen an die Wertstrommethode stellen. Aufbauend auf den acht Gestaltungsrichtlinien des Wertstromdesigns werden in diesem Fachbeitrag Handlungsempfehlungen für die Anwendung der Wertstrommethode in der Prozessindustrie diskutiert.   The eight design guidelines of Erlach‘s Value Stream Design Method work well in streamlining operations in the piece-good industry. In the process and chemical industries, however, production systems exhibit different characteristics, like joint production, that present challenges for the eight step value stream design method. Building on the eight design guidelines, this article discusses the deficits of this method in the process industries and gives recommendations for its adaptatio.

Management of Ground Movement Hazards: An Overview of a JIP

2020 ◽  
Author(s):  
Yong-Yi Wang ◽  
Don West ◽  
Doug Dewar ◽  
Alex Mckenzie-Johnson ◽  
Steve Rapp
Keyword(s):  
Best Practice ◽  
Major Elements ◽  
Ground Movement ◽  
Management Approach ◽  
Hazard Management ◽  
Ground Movements ◽  
Strain Design ◽  
Hazard Avoidance ◽  
Actual Field ◽  
Girth Welds

Abstract Ground movements such as landslides, subsidence, and settlement can pose serious threats to the integrity of pipelines. The consequences of a ground movement event can vary greatly. Certain types of ground movements are slow-moving and can be monitored and mitigated before a catastrophic failure. Other forms of ground movements can be difficult to predict. The most effective approach could be hazard avoidance, proactive means to reduce strain demand on pipelines, and/or building sufficiently robust pipeline segments that have a high tolerance to the strain demand. This paper provides an overview of a Joint Industry Project (JIP) aimed at developing a best-practice document on managing ground movement hazards. The hazards being focused on are landslides and ground settlement, including mine subsidence. This document attempts to address nearly all major elements necessary for the management of such hazards. The most unique feature of the JIP is that the scope included the hazard management approach often practiced by geotechnical engineers and the fitness-for-service assessment of pipelines often performed by pipeline integrity engineers. The document developed in the JIP provides a technical background of various existing and emerging technologies. The recommendations were developed based on a solid fundamental understanding of these technologies and a wide array of actual field experiences. In addition to the various elements involved in the management of ground movement hazards, the JIP addresses some common misconceptions about the adequacy of codes and standards, including: • The adequacy of design requirements in ASME B31.4 and B31.8 with respect to ground movement hazards, • The adequacy of linepipe standards such as API 5L and welding standards such as API 1104 for producing strain-resistant pipelines, • The proper interpretation of the longitudinal strain design limit of 2% strain in ASME B31.4 and B31.8, and • The effectiveness of hydrostatic testing in “weeding out” low strain tolerance girth welds.

An integral solution of the electromagnetic seismograph equation

1960 ◽  
Vol 50 (3) ◽  
pp. 461-465
Author(s):  
R. E. Ingram
Keyword(s):  
Differential Equation ◽  
Green’S Function ◽  
Green's Function ◽  
Integral Solution ◽  
Ground Movement ◽  
Ground Movements ◽  
Angular Movement ◽  
Electromagnetic Seismograph

ABSTRACT In investigating the response of an electromagnetic seismograph to various ground movements it is advantageous to have the solution of the differential equation as an integral. This is done by finding the Green's function, f(s), for the particular instrument. The angular movement of the galvanometer is then θ(t)=q∫0tf(s)x″(t−s)ds where x(t) is the ground movement and prime stands for the operator d/dt. It is sufficient to find one function, F(s), with dF/ds = f(s), to give the response to a displacement test, a tapping test, or a ground movement.

A New Multidimensional Design Method Based on Meta Model Assistance

2017 ◽  
Vol 7 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Nazih Selmoune ◽  
Zaia Alimazighi
Keyword(s):  
Data Warehouse ◽  
Case Studies ◽  
Design Method ◽  
Essential Element ◽  
Design Guidelines ◽  
Data Warehouses ◽  
Multidimensional Model ◽  
Meta Model ◽  
The Real ◽  
Basic Concepts

Data warehouses have become over the last two decades an essential element in the area of economic intelligence. Although the basic concepts related to this technology are now more standardized (multidimensional model, OLAP technology...), the design method issue remains in discussion, since no proposed method does seem attractive enough to be used rigorously in the real case studies. Indeed, most of the 'Data Warehouse projects' simply follow some design guidelines from the most informal methods. In this paper the authors propose an approach based on the use of the sources metadata to provide help in the multidimensional design. Their approach falls into the category of supply-driven methods, and attempts to cover the various stages of the lifecycle of data warehouses design. The proposed method is associated with a MultiDimensional Design Assistance environment (M2DA) to support the automatic and semi-automatic steps, providing the expected forms of assistance, and managing the interaction with the designer.

scholarly journals Sensitivity Analysis of Influencing Factors of Building Slope Stability Based on Orthogonal Design and Finite Element Calculation

2018 ◽  
Vol 53 ◽  
pp. 03076
Author(s):  
RUAN Jin-kui ◽  
ZHU Wei-wei
Keyword(s):  
Finite Element ◽  
Slope Stability ◽  
Design Method ◽  
Orthogonal Design ◽  
Slope Angle ◽  
Friction Angle ◽  
Range Analysis ◽  
Factors Affecting ◽  
Orthogonal Test Design ◽  
The Stability

In order to study the sensitivity of factors affecting the homogeneous building slope stability, the orthogonal test design method and shear strength reduction finite element method were used. The stability safety factor of the slope was used as the analysis index, and the range analysis of results of 18 cases were carried out. The results show that the order of sensitivity of slope stability factors is: internal friction angle, slope height, cohesion, slope angle, bulk density, elastic modulus, Poisson's ratio. The analysis results have reference significance for the design and construction of building slope projects.

Method of Predicting Differential Case Bolt Behavior

2015 ◽  
Author(s):  
Takanori Nukata ◽  
Yasuo Arai ◽  
Mitsunori Kamimura ◽  
Taketoshi Kido ◽  
Masahiko Yamazaki
Keyword(s):  
Contact Surface ◽  
Design Method ◽  
Maximum Load ◽  
Design Guidelines ◽  
Ring Gear ◽  
Bearing Surface ◽  
Surface Pressure Distribution ◽  
Screw Surface ◽  
Bolt Loosening ◽  
Seating Surface

This paper proposes a CAE-based method to predict the maximum load at which bolts start to loosen. The qualitative validity of this method was confirmed using the fastening bolts between the differential case and ring gear. In general, the differential case and ring gear are fastened with bolts. Therefore, it is essential to estimate the maximum load of bolt loosening when designing these bolts. Moreover, prototypes found that tightening bolts are more likely to loosen as the thickness of the differential case or ring gear decreases and becomes easier to deform. This indicates that the deformation of the differential case and ring gear must be considered in bolt design. However, predicting the maximum load is relatively difficult because the behavior of both the screw and the contact surface between the differential case and ring gear is complicated. In contrast, recent transmissions require further weight reduction without sacrificing reliability. Consequently, a method of predicting the maximum load of bolt loosening is required. First, this paper describes a CAE model for estimating the pressure and friction generated at the contact surface between the differential case and ring gear, as well as at the screw surface and bolt seating surface. Furthermore, a method for determining bolt loosening is described that incorporates the pressure and friction on the bolt seating surface into friction circle theory. This method was used to derive the maximum load of bolt loosening. In addition, it was also confirmed that the results qualitatively agree with actual cases of bolt loosening. Second, this paper identifies the relative sliding of the screw surface and contact surface when the load increases. In this case, it was verified that the sliding on the contact surface between the differential case and ring gear induces relative sliding of the screw, followed by sliding of the bolt bearing surface and loosening of the bolt. Finally, this paper refers to design guidelines for reducing the weight of the differential case using an experimental design method. Certain ribs cause non-uniform bolt bearing surface pressure distribution, which likely affects bolt loosening. Through this research, the validity of the method was confirmed and the bolt behavior was clarified when a differential case and ring gear are loaded in one direction. Based on these results, it should be possible to apply this method to more complicated load cases in the future.

scholarly journals Slope stability analysis in the case of probabilistic and semi-probabilistic design method

2019 ◽  
Vol 97 ◽  
pp. 04044
Author(s):  
Hubert Szabowicz
Keyword(s):  
Finite Element ◽  
Internal Friction ◽  
Design Method ◽  
Probability Distributions ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Probabilistic Modelling ◽  
Finite Element Software ◽  
Random Finite Element Method ◽  
Slope Factor

This paper addresses the issue of probabilistic and semi-probabilistic modelling of soil slopes. A slope made of cohesive-frictional soil of specific geometry was analysed as an example. Results were calculated for two methods using the Z-Soil finite element software. It has been assumed that the probability distributions of strength parameters, cohesion and internal friction angle are normal distributions with average values and coefficient of variation = 0.2. Random finite element method (RFEM) has been used for probabilistic modelling. Random fields of cohesion and internal friction angle have been generated using the Fourier series method (FSM). Monte Carlo simulation has been used to calculate the statistics of the slope factor of safety in order to determine the probability of failure. Moreover, assumed parameter distributions allowed to determine safe characteristic values used in the semi-probabilistic partial factors method. Both approaches have been compared in the article.

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