scholarly journals CEOHYDRAULIC INVESTIGATIONS OF RUBBLE MOUND BREAKWATERS

1988 ◽  
Vol 1 (21) ◽  
pp. 166 ◽  
Author(s):  
W. Burger ◽  
H. Oumeraci ◽  
H.W. Partenscky
Keyword(s):  
Pore Pressure ◽  
Scale Effects ◽  
Numerical Models ◽  
Model Tests ◽  
Physical Models ◽  
Core Material ◽  
Scale Model ◽  
Small Scale ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

Due to the increase of ship sizes in recent decades a number of harbours and terminals have been built in deeper waters. Accordingly, the structures which have to provide protection against wave action become higher, too. In most cases, these protective structures are of the rubble mound type. Under such conditions the flow induced by waves within the breakwater and the related geotechnical behaviour of the rubble mound fill become more significant fcr the overall stability and should be considered in the design. In addition, it is known that the scales usually adopted in hydraulic models (1:30 to 1:60) for investigating the stability of large rubble mound breakwaters generally lead to scale effects with respect to the flow field inside the breakwater. This means that small-scale model tests are not appropriate for investigating the internal flow patterns or for evaluating the pore pressure field induced by the incident waves in,the core material. because of the uncontrolled conditions in the prototype, and since the actual permeability of the prototype rubble mound fill cannot be predicted (segregation, settlement, variation in grading, etc.), the use of large-scale physical models seems to be the most promising method for basic investigations of this kind. Moreover, the results of such largescale model tests may be used to validate the usual smaller scale models and to calibrate numerical models. Therefore, it is one of the objectives of our research programme on rubble mound breakwaters, which started in 1987, to concentrate on the evaluation of the wave-induced flow and pore pressure distribution within the breakwater.

Prototype measurements and small-scale model tests of wave overtopping at shallow rubble-mound breakwaters: the Ostia-Rome yacht harbour case

2009 ◽  
Vol 56 (2) ◽  
pp. 154-165 ◽  
Author(s):  
Leopoldo Franco ◽  
Jimmy Geeraerts ◽  
Riccardo Briganti ◽  
Marc Willems ◽  
Giorgio Bellotti ◽  
...  
Keyword(s):  
Model Tests ◽  
Scale Model ◽  
Small Scale ◽  
Wave Overtopping ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters ◽  
Small Scale Model

scholarly journals ON THE STABILITY OF RUBBLE-MOUND BREAKWATERS Jose Joaquim

2011 ◽  
Vol 1 (7) ◽  
pp. 34
Author(s):  
Jose Joaquim Reis De Carvalho ◽  
Daniel Vera-Cruz
Keyword(s):  
Model Tests ◽  
Scale Model ◽  
Small Scale ◽  
Existing Structures ◽  
Rubble Mound ◽  
The Stability ◽  
Steep Slopes ◽  
Rubble Mound Breakwaters ◽  
The Waves ◽  
Level 2

Until the beginning of the second quarter of the present century, characteristics of rubble-mound breakwaters were determined by entirely empirical methods, although harbour engineers had been deal ing with this problem for man;> centuries. As a rule, designers merely compared the case under study with existing structures, prescribing sturdier breakwaters when those located in shores with a similar exposure had not withstood the most violent storms acting on them. The first empirical formula for breakwater design did not appear before 1933, but this and other similar formulas did not go beyond ordering and reducing the use of arbitrary methods in the choice of the elements making up the breakwater slopes more directly subjected to wave action; no sensible progress resulting there? From for the design methods of these structures.lt can even be stated that, due to the use of Iribarren's formula - the most widely used in Europe - which leads to the utilization of too heavy blocks placed in steep slopes (about ^/3)» a tendency began to be observed in designers, towards a considerable reduction of these slopes. Such a situation which, bearing in mind the knowledge available until about 10 years ago, was perfectly admissible, has been subjected to considerable changes thanks to: 1) the enormous advances achieved in the theoretical field, which placed our knowledge on the majority of Maritime Hydraulics subjects on a satisfactory level; 2) the invaluable help of small scale model tests, and3) our improved knowledge on natural phenomena which makes possible a comparatively satisfactory estimate of the characteristics of the waves to be anticipated at any point of the coast*We have merely to persevere along the route followed in the latter years in order to determine more accurate values fir the coefficients of the available formulas, representing the results obtained by means of graphs and tables, resorting for that purpose both to model tests and to a careful observation of the behaviour of completed structures throughout the world, above all those which underwent damages. On the other hand efforts should not be spared in concentrated attempts to discover new formulas as phenomena are, no doubt much too complex in the destruction of a breakwater to allow of a single satisfactory scheaetization. It should be borne in mind that, in spite of the laboratory tests recently carried out, our knowledges is limited to the area directly affected by the wave breaking and so a total knowledge of the stability of rubble-mound breakwaters lies still a long way ahead.

scholarly journals Photogrammetric analysis of rubble mound breakwaters scale model tests

2016 ◽  
Vol 3 (3) ◽  
pp. 541-559 ◽  
Author(s):  
Rute Lemos ◽  
◽  
Maria A. R. Loja ◽  
João Rodrigues ◽  
José A. Rodrigues
Keyword(s):  
Model Tests ◽  
Scale Model ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

scholarly journals SCALE EFFECTS IN RUBBLE-MOUND BREAKWATERS

1972 ◽  
Vol 1 (13) ◽  
pp. 102
Author(s):  
Kenneth W. Wilson ◽  
Ralph H. Cross
Keyword(s):  
Boundary Layer ◽  
Scale Effects ◽  
Layer Growth ◽  
Effective Porosity ◽  
Model Tests ◽  
Experimental Results ◽  
Linear Wave ◽  
Reflection And Transmission ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

In conducting model tests of wave transmission through permeable rubble-mound breakwaters, it is impossible to satisfy simultaneously the Froude and Reynolds criteria for dynamic similarity. The common practice has been to scale the wave parameters and breakwater dimensions in accordance with the Froude Number, and to use large models. This study represents an attempt to develop theoretical expressions for the coefficients of reflection and transmission as functions of the effective porosity of the breakwater structure, as influenced by the Reynolds-dependent boundary layer growth an the pores. These expressions use linear wave theory and boundary layer theory to estimate the effective decrease in pore diameter due to growth of the displacement boundary layer thickness in the pore. The theoretical expressions were compared with experimental results from a series of three model tests with breakwaters having vertical faces and using gravel with diameters of 1.37 in., 0.762 in., and 0.324 in. respectively. The prototype to model ratios (using the largest model as the prototype) were 1/1.80 and 1/4.23 respectively. The experimental results show clearly the existence of scale effects in both coefficients of reflection and transmission. The theoretical expressions were found to overestimate the scale effect in reflection and to underestimate it in transmission.

scholarly journals Experimental Analysis of Wave Overtopping: A New Small Scale Laboratory Dataset for the Assessment of Uncertainty for Smooth Sloped and Vertical Coastal Structures

2019 ◽  
Vol 7 (7) ◽  
pp. 217 ◽  
Author(s):  
Hannah E Williams ◽  
Riccardo Briganti ◽  
Alessandro Romano ◽  
Nicholas Dodd
Keyword(s):  
Time Series ◽  
Physical Model ◽  
Numerical Models ◽  
Vertical Wall ◽  
Model Tests ◽  
Physical Models ◽  
Small Scale ◽  
Wave Condition ◽  
Wave Overtopping ◽  
Physical Model Tests

Most physical model tests carried out to quantify wave overtopping are conducted using a wave energy spectrum, which is then used to generate a free surface wave time series at the wave paddle. This method means that an infinite number of time series can be generated, but, due to the expense of running physical models, often only a single time series is considered. The aim of this work is to investigate the variation in the main overtopping measures when multiple wave times series generated from the same spectrum are used. Physical model tests in a flume measuring 15 m (length) by 0.23 m (width) with an operating depth up to 0.22 m were carried out using a stochastic approach on two types of structures (a smooth slope and a vertical wall), and a variety of wave conditions. Results show variation of overtopping discharge, computed by normalising the range of the discharges at a certain wave condition with the maximum value of the discharge in the range up to 10 % , when the same wave time series is used, but this range increases to 75 % when different time series are used. This variation is found to be of a similar magnitude to both the one found with similar experiments looking at the phenomena in numerical models, and that specified by the confidence bounds in empirical methods.

Analytical and model studies of reinforcement of a layer of granular fill on a soft clay subgrade

1987 ◽  
Vol 24 (4) ◽  
pp. 611-622 ◽  
Author(s):  
J. P. Love ◽  
H. J. Burd ◽  
G. W. E. Milligan ◽  
G. T. Houlsby
Keyword(s):  
Soft Clay ◽  
Model Tests ◽  
Reinforced Soil ◽  
Physical Models ◽  
Scale Model ◽  
Small Scale ◽  
Membrane Action ◽  
Geogrid Reinforcement ◽  
Granular Fill ◽  
Soft Clay Subgrade

The effectiveness of geogrid reinforcement, placed at the base of a layer of granular fill on the surface of soft clay, has been studied by small-scale model tests in the laboratory. In the tests, monotonic loading was applied by a rigid footing, under plane strain conditions, to the surface of reinforced and unreinforced systems, using a range of fill thicknesses and subgrade strengths. Continuous measurements were made of footing load and footing displacement, and deformations of the subgrade and of the geogrid reinforcement were measured from photographs. From these measurements the different mechanisms of failure in the unreinforced and reinforced system were established. Performance of reinforced systems was found to be superior even at small deformations, owing to the significant change in the pattern of shear forces acting on the surface of the clay, brought about by the presence of the reinforcement. Membrane action of the reinforcement only became significant at large deformations.A finite element computer program has been specially formulated to allow inclusion of a thin reinforcing layer, and to handle correctly the large deformations and strains induced in the physical models. This formulation is able to reproduce satisfactorily the main features of behaviour observed in the models, and may now be used with some confidence to perform accurate predictions for full-scale structures. Key words: bearing capacity, clays, finite elements, foundations, geotextile, granular materials, model tests, reinforced soil, roads.

scholarly journals Using 3D Modelling Techniques for Surveys in Two Dimensional Scale Model Tests of Breakwaters

2018 ◽  
Vol 26 (2) ◽  
pp. 15-23
Author(s):  
Rute Lemos ◽  
Maria Henriques ◽  
António Muralha ◽  
Ricardo Jónatas ◽  
Conceição Fortes ◽  
...  
Keyword(s):  
3D Modelling ◽  
Model Tests ◽  
Scale Model ◽  
Two Dimensional ◽  
Experimental Conditions ◽  
Irregular Wave ◽  
Scale Models ◽  
Modelling Techniques ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

AbstractThis paper focuses on a study of different methodologies for surveying two-dimensional scale models of rubble mound breakwaters.Tests were conducted in one of the LNEC’s irregular wave flumes and involved the use of four different methodologies using photogrammetric and 3D scanning techniques.This paper describes the materials and methods used during the experiments, as well as the results obtained.The data analysis contains the profiles and comparison of the meshes used in each of the techniques, in order to evaluate their application in scale model tests of rubble mound breakwaters. Also, the specific experimental conditions needed for using each of these techniques were investigated.

Small‐Scale Model Tests of Structural Steel Assemblies

1989 ◽  
Vol 115 (8) ◽  
pp. 1999-2015 ◽  
Author(s):  
Benjamin J. Wallace ◽  
Helmut Krawinkler
Keyword(s):  
Structural Steel ◽  
Model Tests ◽  
Scale Model ◽  
Small Scale ◽  
Small Scale Model
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