نوع مقاله : پژوهشی
نویسندگان
1 دانشیار گروه مهندسی رودخانه و حفاظت سواحل، پژوهشکده حفاظت خاک و آبخیزداری، سازمان تحقیقات آموزش و ترویج کشاورزی، تهران، ایران
2 دانشجوی دکتری و رئیس اداره کل مهندسی سواحل و بنادر، سازمان بنادر و دریانوردی ایران
3 دانشجوی دکتری و معاون اداره کل مهندسی سواحل و بنادر، سازمان بنادر و دریانوردی ایران
4 دکتری تخصصی اداره کل مهندسی سواحل و بنادر، سازمان بنادر و دریانوردی ایران
5 دکتری تخصصی عمران، سواحل، بنادر و سازه های دریایی، دانشگاه تبریز، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction and Goal
Coastal areas in the foothills of coastal watersheds are important due to the presence of a considerable portion of the watershed's inhabitants, serving as a hub for of services and production between the inland parts of the country and abroad, as well as for sea-oriented activities. On the other hand, the coastal zone is affected by erosion and deformation due to the inherent lithology of rock units and coastal landforms, as well as the hydrodynamic conditions of waves. Therefore, sea-oriented activities are carried out under the shelter of protective structures, especially breakwaters. The aim of this research was to investigate the stability of rock mass coastal protection structures under the impact of waves from the northern Persian Gulf.
Materials amd Methods
In classifying protective structures, two aspects are considered: structural characteristics and their constituent materials, and the arrangement and location of breakwaters. To achieve the goal of this research, the stability of a profile of the protective structure of the Genaveh Port with the highest impact surface of the breaking waves near the head of the breakwater with a specific wave pattern was tested using a modeling method in the wave simulation laboratory of the National Institute of Soil Conservation and Watershed Management. The port of Genaveh in the northern Persian Gulf is of great commercial and fishing importance.
Given the challenges such as severe wave interference, coastal erosion, and poor performance of breakwaters against the prevailing waves in the region, it is necessary to more closely examine the stability of protective structures in this area. The breakwaters of this port play a vital role in the stability and safety of the port basin; therefore, analyzing their behavior under different hydrodynamic conditions using modeling in the wave-making flume can provide valuable consequences in optimizing the design and performance of these structures. In this study, the dimensions of the armor layer of the protective structure (breakwater) of the port of Genaveh were determined. The weight of the rock blocks was one of the influential metrics in selecting the most appropriate option for the armor. The important metrics in the design of the protective structure and rubble mound breakwater were divided into three categories: environmental metrics (related to waves), hydraulic metrics, and structural metrics. The damage to the armor layer (ha) was estimated by counting the number of displaced armor blocks or by measuring the eroded area of the armor layer in the transverse profile. The method of calculation the index was based on condition without displacement of armor blocks that were shaken individually or those that were displaced, individually, from their original location by a small and specific amount. The run-up (Ru) and rundown (Rd) levels of water on the slope of the structure are created in each wave impact. These levels are defined relative to the static level and are among the important design metrics. Modeling was implemented using a two-dimensional wave generator flume with a length of 33 m and a width of 5.5 m, with a water intake capacity of up to 1.5 m depth. The structural dimensions were scaled down to a scale of 1:20. The hydrodynamic conditions for the stability assessment of the selected profile included the JONSWAP irregular wave spectrum with a return period of 50 years, an effective wave height (Hs) of 2.7 m, and an amplitude of 6 seconds. This specification with a factor of 1.2 was also used to account for very critical conditions. These waves were radiated for 100 to 110 minutes, equivalent to 1500 breakwater, and in four conditions: high tide (sea tide with wind and wave surge), low tide, one-year return period, and 1.2 times of high tide on the selected profile (P6). The changes resulting from the impact of breakwater were investigated by taking before and after profile photographs using the image measurement method.
Results and Discussion
The results of the physical model to study the stability of the coastal protection structure designed for the northern wave conditions of the Persian Gulf showed that the height and slope design for the construction of Genaveh Port were acceptable. In other words, the design presented for the construction of the protection structure in the Genaveh region was reliable from both functional and structural perspectives. On the other hand, in this design, the armor layer of the protection structure was changed in the slope profile and partial settlement in the filter layer under very critical conditions. ِDuring tests related to high tide conditions, an mean of 88% of the observed run-up was at or below the design head of the structure. Displacement of armor layer pieces was also observed only at conditions equivalent to 1.2 times high water and to a very limited extent. Also, after 1300 waves of radiation, the filter layer gradually settled. These conditions were consistent with a 100-year wave return period. Therefore, it was necessary to redesign the structure with a higher height and heavier stone dimensions.
Conclusion and Suggestion
In this research, using the physical model of the Genaveh Port protective structure, the interaction of different wave conditions on the structure, especially the rock mass armor layer, was successfully measured, and stable conditions were predicted for implementation and cost reduction for the implementing agency (Ports and Maritime Organization, PMO). Therefore, in conditions where the breakwater are very critical and coincide with the highest astronomical tide level, the protective structure of Genaveh Port breaks. Therefore, it is recommended that the implementing agency prevent users from traveling along the breakwater and consider other protective measures. In addition, it is suggested that the method used in this study be used to optimize and develop protective structures in other similar coastal areas in the northern Persian Gulf.
کلیدواژه‌ها [English]
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