scholarly journals SCOUR AROUND MODEL PIPELINES DUE TO WAVE ACTION

1976 ◽  
Vol 1 (15) ◽  
pp. 94 ◽  
Author(s):  
John B. Herbich
Keyword(s):  
Scale Effects ◽  
Initial Slope ◽  
Extensive Literature ◽  
Ocean Bottom ◽  
Buried Pipe ◽  
Offshore Pipelines ◽  
Size Number ◽  
Equilibrium Profiles ◽  
Equilibrium Profile ◽  
Pipeline Failures

The size, number and application of offshore pipelines are steadily increasing. At the same time, the incidence of reported pipeline failures is also increasing. There appear to be several reasons for these failures, and they can be placed in two basic categories: 1. inadequate cover, and 2. low "specific gravity" of the pipeline. Under the first category the depth of burial may be insufficient, the type of burial material may be inferior to the material alongside the trench, or the compaction of cover material may be inadequate. Under the second category the pipe may actually float up to the surface from the ocean bottom as material around the buried pipe liquifies. An extensive literature search revealed that many studies were conducted by Meyers (1936), Waters (1939), Johnson (1940), W.E.S. (1940), Rector (1954), Wiegel, et al (1954), Saville (1957), Iwagaki and Noda (1962), Nayak (1972), Noda (1972), and Earattupuzha (1974). In general, two types of "equilibrium profiles" were developed in the laboratory flumes, the "ordinary" and the "storm" (sometimes referred to as summer and winter profiles). Despite numerous previous investigations, knowledge of the "scale effects" involved in equilibrium beach profiles is inadequate. Many authors have analyzed model data without stating the relation between model and prototype dimensions. In addition, many have claimed certain phenomena observed in the model to be independent of initial slope. An extensive laboratory study was conducted to evaluate the development of underwater bars and scour patterns with the pipeline buried at various depths below the ocean bottom. Pictures of the beach profile were taken at specific time intervals through the glass wall of the wave tank. Attempts were made to correlate equilibrium profile geometric quantities, such as depth of offshore bar, scour depth and berm height with the wave characteristics. Qualitative agreement between laboratory and natural beach profiles were demonstrated by trial and error fitting of one to the other.

Equilibrium Profile of Modern Belted Radial Ply Tires: Its Determination and Performance Benefits

2013 ◽  
Vol 41 (2) ◽  
pp. 127-151
Author(s):  
Rudolf F. Bauer
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
Finite Element Methods ◽  
Mathematical Analysis ◽  
Internal Stresses ◽  
Stress Concentrations ◽  
Equilibrium Profiles ◽  
Equilibrium Profile ◽  
And Performance ◽  
Beneficial Property

ABSTRACT The benefits of a tire's equilibrium profile have been suggested by several authors in the published literature, and mathematical procedures were developed that represented well the behavior of bias ply tires. However, for modern belted radial ply tires, and particularly those with a lower aspect ratio, the tire constructions are much more complicated and pose new problems for a mathematical analysis. Solutions to these problems are presented in this paper, and for a modern radial touring tire the equilibrium profile was calculated together with the mold profile to produce such tires. Some construction modifications were then applied to these tires to render their profiles “nonequilibrium.” Finite element methods were used to analyze for stress concentrations and deformations within all tires that did or did not conform to equilibrium profiles. Finally, tires were built and tested to verify the predictions of these analyses. From the analysis of internal stresses and deformations on inflation and loading and from the actual tire tests, the superior durability of tires with an equilibrium profile was established, and hence it is concluded that an equilibrium profile is a beneficial property of modern belted radial ply tires.

SOME FEATURES OF THE EQUILIBRIUM COASTAL PROFILE FOR DIFFERENT INITIAL BED SLOPES BASED ON MODELLING STUDY

2017 ◽  
Author(s):  
Dmitry Korzinin ◽  
Dmitry Korzinin ◽  
Igor Leontiev ◽  
Igor Leontiev
Keyword(s):  
Time Scales ◽  
Wave Impact ◽  
Grain Sizes ◽  
Equilibrium Profiles ◽  
Equilibrium Profile ◽  
The Mean ◽  
Wave Conditions ◽  
Bed Slope ◽  
Coastal Profile ◽  
Modelling Study

Modelling study of the equilibrium profiles formed on sandy coasts of different bed slopes and grain sizes under the various wave conditions was realized by using the CROSS-P and Xbeach morphodynamic models. A special criterion taking into account a total volume of bed deformations per one hour was suggested to determine the conditions of profile stabilization. For both models the time scales of equilibrium profile formation were found to be the same. However, the deformation magnitudes differed significantly. Bed deformations were computed on the whole profile length over the 200-hours duration of wave impact. It was concluded that both models predict a trend of the bed slope toward a stable value. CROSS-P model shows the widening of accumulative terrace during the profile evolution. The mean slope of the equilibrium profile was found to depend on the initial bed slope.

Development of a prototype for modelling soil–pipe interaction and its application for predicting uplift resistance to buried pipe movements in sand

2018 ◽  
Vol 55 (10) ◽  
pp. 1451-1474 ◽  
Author(s):  
Yousef Ansari ◽  
George Kouretzis ◽  
Scott W. Sloan
Keyword(s):  
Scale Effects ◽  
Reaction Force ◽  
Failure Surface ◽  
Relative Displacement ◽  
Published Data ◽  
Buried Pipe ◽  
Image Velocimetry ◽  
Close Range ◽  
Uplift Resistance

This paper presents a testing rig for measuring the reactions on rigid pipes buried in sand during episodes of relative displacement. Following a detailed presentation of the 1g prototype, the test preparation procedure, and the characterization of the test sand’s shear strength and dilation potential under the low confining stresses pertinent to the problem, the paper focuses on the workflow devised to obtain accurate measurements of friction and arching effects, and accordingly normalize them to account for scale (stress level) effects. Emphasis is put on demonstrating the effectiveness of the sand deposition method for accurately controlling the density of the sample, and on quantitatively assessing its uniformity. Measurements obtained during a series of uplift tests, including reaction force – pipe displacement curves and images of the developing failure surface, facilitated by particle image velocimetry and close-range photogrammetry techniques, are compared against published data and analytical methods. The results lead to the development of a new simplified formula for calculating the uplift resistance to buried pipe movements in sand: capable of accounting for scale effects, yet simple enough to be used for the analysis of pipes in practice.

scholarly journals CARIBBEAN BEACH-FACE SLOPES AND BEACH EQUILIBRIUM PROFILES

1988 ◽  
Vol 1 (21) ◽  
pp. 120 ◽  
Author(s):  
John D. Boon ◽  
Malcolm O. Green
Keyword(s):  
Objective Measure ◽  
Field Measurements ◽  
The United States ◽  
Gravitational Acceleration ◽  
Sediment Grain Size ◽  
Practical Result ◽  
Average Value ◽  
Caribbean Islands ◽  
Equilibrium Profiles ◽  
Equilibrium Profile

Field measurements performed on two Caribbean islands revealed that two-dimensional nearshore bottom morphology is well represented by Dean's (1977) model of the beach equilibrium profile, h - A xm, where h is depth below mean water level at a distance x offshore and A is a scale factor. For the curvature, m, we obtained an average value of approximately m - 1/2 through least squares curve fitting of observed profile data, yielding a more concave and therefore steeper profile inshore than m — 2/3, the average previously reported by Dean for quartz sand beaches in the United States. Furthermore, an objective measure of beach steepness was found to be A-*-'1", a quantity which utilizes both of Dean's parameters and which may serve as a surrogate for the beach-face slope, tan /3, on highly concave beaches. Reasonable correlations were found between A?-'m and the environmental parameter, H^ /gDT , where H^ is breaker height, D is sediment grain size, T is wave period and g is gravitational acceleration. Improved prediction of Caribbean beach slopes and beach equilibrium profiles is an important practical result.

scholarly journals LABORATORY STUDY OF SCALE EFFECTS IN TWO-DIMENSIONAL BEACH PROCESSES

2011 ◽  
Vol 1 (8) ◽  
pp. 14 ◽  
Author(s):  
Yuichi Iwagaki ◽  
Hideaki Noda
Keyword(s):  
Wave Height ◽  
Scale Effects ◽  
Breaking Waves ◽  
Two Dimensional ◽  
Sediment Size ◽  
Beach Processes ◽  
Time Period ◽  
Equilibrium Profile ◽  
Profile Changes ◽  
Constant Slope

In order to disclose the essential relationship between the beach processes and wave characteristics, two dimensional model tests are often performed for beach profile changes due to incident breaking waves normal to the beach. In applying the results of such experiments to the prototype of beaches, the scale effects of waves and sediments on the beach processes with equilibrium beach profiles should necessarily be considered. In this paper, as an approach to solve this problem in two dimensional beach studies, the effects of wave height and sediment size on the shore line movement and equilibrium beach profiles are discussed based on the results of experiments made by the authors and other experiments with smaller and larger scales by some researchers. It has been found that the ratio of wave height to sediment diameter is a very significant factor in this problem. In addition, the changes m a character of breaking waves during the time period of wave action from the beach having an initial constant slope to that with an equilibrium profile are presented.

Retroerosion in a TBG Gas Pipeline Crossing and its Rehabilitation

2019 ◽  
Author(s):  
Cesar Augusto Costa ◽  
Walter Schultz Neto ◽  
Thiago Wichrestink Zozula
Keyword(s):  
Process Analysis ◽  
Temporal Trends ◽  
Gas Pipeline ◽  
Aerial Photographs ◽  
Erosion Process ◽  
Buried Pipe ◽  
Base Level ◽  
Channel Erosion ◽  
Equilibrium Profile ◽  
Pipeline Crossing

Abstract This Paper presents a case study of the Jardim Novo Maracanã stream situated in Campinas, São Paulo, in which recent streambed modifications were characterized, aiming to define the rates and the potential erosions along the channel alignment of which have Bolivia-Brazil Gas Pipeline crossing. Its presents the erosion process analysis and mitigation concepts aimed at the pipeline and fiber optic cables facilities integrity, as well as to indicate the design issues, considering the streambed deepening in this watershed. For this, satellite images and aerial photographs were collected in different periods, soil and subsoil surveys were performed, information on rainfall and watershed characteristics was analyzed, as well as hydrological and hydrotechnical studies were developed. These studies included geotechnical channel and banks analyzes, the spatial and temporal trends of the fluvial geomorphology evolution and the infrastructures safety conditions analysis. It was concluded that a new channel erosion process occurred after the streambed was filled by recent sediments. This process is associated with an increase floods magnitude, the slopes occupation intensification with the county urbanization and the streambed conditions changes, from an alignment sinuous to rectilinear and from a shallow to deeper channel. Once initiated, the channel erosion process maintained its retroerosion, i.e. its “headcutting” trend, deepening its equilibrium profile to its stratigraphic base level, located about 5.0 m below the 2014 stream bottom, in the pipeline cross section. Alternative concepts for the infrastructure integrity rehabilitation in these new morphological-fluvial conditions were also developed and dimensioned. Among these, the rectangular culverts alternative was adopted. They support a landfill at the crossing with the buried pipe and have to 100-year return period peak flows capacity.

SOME FEATURES OF THE EQUILIBRIUM COASTAL PROFILE FOR DIFFERENT INITIAL BED SLOPES BASED ON MODELLING STUDY

2017 ◽  
Author(s):  
Dmitry Korzinin ◽  
Dmitry Korzinin ◽  
Igor Leontiev ◽  
Igor Leontiev
Keyword(s):  
Time Scales ◽  
Wave Impact ◽  
Grain Sizes ◽  
Equilibrium Profiles ◽  
Equilibrium Profile ◽  
The Mean ◽  
Wave Conditions ◽  
Bed Slope ◽  
Coastal Profile ◽  
Modelling Study

Modelling study of the equilibrium profiles formed on sandy coasts of different bed slopes and grain sizes under the various wave conditions was realized by using the CROSS-P and Xbeach morphodynamic models. A special criterion taking into account a total volume of bed deformations per one hour was suggested to determine the conditions of profile stabilization. For both models the time scales of equilibrium profile formation were found to be the same. However, the deformation magnitudes differed significantly. Bed deformations were computed on the whole profile length over the 200-hours duration of wave impact. It was concluded that both models predict a trend of the bed slope toward a stable value. CROSS-P model shows the widening of accumulative terrace during the profile evolution. The mean slope of the equilibrium profile was found to depend on the initial bed slope.

Context

1999 ◽  
Author(s):  
Alan Graham
Keyword(s):  
Water Temperature ◽  
Sea Level ◽  
Middle Eocene ◽  
Extensive Literature ◽  
Ocean Bottom ◽  
Sources Of Information ◽  
Sea Level Changes ◽  
The North ◽  
Temperature Records ◽  
Forcing Mechanisms

The interaction between vegetation and the environment over time is one of the most complex of the Earth’s integrated systems. In addition to the direct methodologies of paleopalynology and paleobotany, there are other techniques that provide independent sources of information for interpreting this interaction. These include paleotemperature analysis, sea-level changes, and faunal history. The first two are also forcing mechanisms as discussed in Chapter 2, but for this survey the summary curves can also serve as convenient context information. Each is a vast subject with an extensive literature, and all are presently generating considerable discussion. For paleotemperature analysis, unsettled issues include the extent of temperature change in equatorial waters during the Early and Middle Tertiary, which would affect the poleward transport of heat by conveyer-belt mechanisms. Estimates range from surface waters as warm or warmer than the present to considerably cooler. For the Neogene, CLIMAP estimates based on the ecology of coccolithophores, diatoms, radiolarians, and especially foraminifera are that temperatures in the tropics did not cool significantly; modeling results, terrestrial paleontological evidence, and new Barbados coral data suggest they cooled by ~5°C. There is uncertainty as to when glaciations began on Antarctica; recent estimates range from the Early Eocene to late Middle Eocene to Middle Oligocene (45-35 Ma; Birkenmajer, 1990; Leg 119 Shipboard Scientific Party, 1988). This affects interpretation of 18O values during the Paleogene because they could reflect temperature alone or could be due to ocean water temperature and ice volume changes. Another challenge is to unravel the extent to which benthic temperature records track insolation-induced changes in water temperature versus new thresholds in ocean bottom-water circulation. Discussions of sea-level fluctuation are presently focused on their causes during the preglacial Early Cenozoic. In faunal history the timing of the North American Land Mammal Ages (NALMAs) or provincial ages are being revised. For vegetational history much of the older literature describes events in terms of geofloras, but this conceptual context, at minimum, requires substantial renovation, and the boreotropical hypothesis is emerging as an alternative for envisioning biotic events in the high northern latitudes.

scholarly journals Predicting Crenulate Bay Profiles from Wave Fronts: Numerical Experiments and Empirical Formulae

Geosciences ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 208
Author(s):  
Mariano Buccino ◽  
Sara Tuozzo ◽  
Margherita C. Ciccaglione ◽  
Mario Calabrese
Keyword(s):  
Wave Front ◽  
Numerical Experiments ◽  
Static Equilibrium ◽  
Wave Direction ◽  
Wave Fronts ◽  
Equilibrium Profiles ◽  
Equilibrium Profile ◽  
Analysis Of Results ◽  
Specific Shape ◽  
Shape Equation

For crenulate-shaped bays, the coastal outline assumes a specific shape related to the predominant waves in the area: it generally consists of a tangential zone downcoast and a curved portion upcoast. Many coastal engineers have attempted to derive an expression of the headland bay shapes that emerge when a full equilibrium is reached (stable or dynamic). However, even though models for static equilibrium bays exist, they are merely of an empirical kind, lacking further insight on relationships between incident wave characteristics and beach shape. In addition, it is commonly believed that shoreline profiles tend to follow wave fronts, but this has been never fully verified. In this paper, we investigate a possible correlation between static equilibrium profiles and wave front shapes. Numerical experiments have been performed using the MIKE 21 Boussinesq Wave module, and the generated wave fronts have been compared to the hyperbolic-tangent equilibrium profile. A thoughtful analysis of results revealed that a single-headland equilibrium profile is merely the wave front translated perpendicularly to the wave direction at the headland tip, without any influence of wave period or in wave direction. A new function called the “wave-front-bay-shape equation” has been obtained, and the application and validation of this formula to the case-study bay of the Bagnoli coast (south-west of Italy) is described in the paper.

scholarly journals EQUILIBRIUM PROFILES OF COARSE MATERIAL UNDER WAVE ATTACK

1974 ◽  
Vol 1 (14) ◽  
pp. 54 ◽  
Author(s):  
E. Van Hijum
Keyword(s):  
Research Programme ◽  
Design Criteria ◽  
Coarse Material ◽  
Equilibrium Profiles ◽  
Equilibrium Profile ◽  
Gravel Beaches

In order to obtain design criteria for artificial gravel beaches, a research programme was drawn up to study the behaviour of gravel beaches under wave attack. The present paper gives the main results of the first step in this programme, viz. the determination of the dimensions, form and way of formation of an equilibrium profile under regular, perpendicular wave attack. One of the conclusions is that gravel with a D0(,

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