This thesis presents an original theoretical investigation, based on diffraction theory (extended for permeable structures by Sollitt & Cross [56]), of the performance of segmented rubble mound breakwaters. The amount of protection offered by such a breakwater is a function of the rubble construction (characterized by porosity and permeability), geometry and spacing of segments as well as depending on the the characteristics of the incident wave field. To explore the influence of these factors on the performance of these breakwaters, the diffraction by three related structures have been considered :a periodic array of impermeable blocks, a single continuous rectangular section permeable structure and a periodic array of permeable blocks in shallow water.

Black Sea coast line is a hazardous region especially in winter due to the dominant wave action. Therefore, rubble mound breakwaters used as ship shelters are vital structures especially for the fishermen. Construction of the breakwater requires good quality durable armourstones. Due to the nature of the rubble mound breakwaters, armourstones having various sizes and types are used in the construction of these structures. The deterioration of these armourstones with time in the form of abrasion and disintegration may result in the failure of the breakwater. Therefore, it is important to investigate the durability and quality of the armourstones to be used in these structures. In this thesis, the properties of the armourstones taken from five rock quarries and used in the Hisar&ouml / n&uuml / (Bartin), the Tarlaagzi (Bartin) and the Alapli (Zonguldak) rubble mound breakwaters were studied both in field and laboratory in order to assess their qualities and long term durabilities. Based on the in-situ observations and laboratory tests, the Kavakdere, Kavukkavlagi and the Tarlaagzi limestones are good (durable) rocks. However, the &Ccedil / &ouml / mlek&ccedil / ikuyu andesite is found to be generally marginal rock, and the Kiran sandstone is poor rock. CIRIA/CUR, RDId, RERS and Wet-Dry strength ratio classifications are in good agreement with the in-situ observations and the results of the laboratory tests. However RDIs, Average Pore Diameter and Saturation Coefficient classifications do not fully reflect the reality.

There are some empirical formulas used in the design of rubble mound breakwaters to find the weight of armour layer stone. The effect of wave grouping and spectral shape could not put into these design formulas since their effects are still under question. The influences of wave groups and spectral shape on the stability of rubble mound breakwaters have been investigated by several researchers up to now. However, results were not conclusive in these researches, where different wave grouping and spectral shape parameters were used. This study aims to investigate the influences of wave groups and spectral shape on the stability of rubble mound breakwaters by means of hydraulic model experiments. According to the result of the experiments, the damage to breakwater armour layer is almost same for different spectrum shapes and pronounced wave grouping, under the condition of similar wave statistics. Experiments also indicated that the wave trains with same significant wave height, H1/3, but with different distribution of the heights of extreme waves which were defined as wave heights higher than H1/3 in this study, cause different damage levels. Based on these results, extended experiments were conducted to observe the effect of heights of extreme waves in a wave train on the stability of rubble mound breakwaters. Results of the experiments showed that the higher the extreme waves are, the more destructive the wave train is. By carrying experimental results into design conditions, it was shown that a wave train with high extreme waves may affect the design weight of armour stone. Finally, in order to achieve more practical tools for engineering applications, occurrence probabilities of extreme waves under different spectral shapes were obtained by a numerical simulation. As a result, for different occurrence probabilities of extreme waves under the most widely used spectrums of PM and JONSWAP, necessary weight of armour stone was given in a range comparing with the formula of Meer. Moreover, it was noted that the spectral shape indirectly affects the stability not due to the wave grouping but due to the extreme waves in a wave train since the occurrence probability of the high extreme waves becomes higher as the spectral shape becomes narrower under same significant wave height condition.

Coastal defense structures have primary importance from obtainabilty of resources and benefits served by the coastal regions point of view. However, the construction of coastal defense structures demand a high amount of investment. Therefore, in order to reduce the risk of collapse of these structures, model studies should be carried during the design process. In this study, model investigations were carried out on Eastern Black Sea Highway Project regarding the serviceability and damage thus stability parameters. 5 different models were constructed as berm type rubble-mound breakwaters using Van Der Meer&rsquo / s approach and berm design guidelines, with a scale of 1/31.08 and they were tested both for breaking and non-breaking waves. The experiments took place in the Coastal and Harbor Engineering Laboratory of the Middle East Technical University, Civil Engineering Department. The models were constructed and tested with different berm widths and armor stone sizes forming the back armor layer in order to examine the effect of these design parameters on the stability and serviceability of the coastal defense structure to obtain the optimum alternative cross-section. Cumulative damage was minimum for the cross-section constructed with berm width 15 m assigning the width of the prototype. Water spray and run-up values were also not significant. The test results were confirming with Van Der Meer design approach.