Проект подвесного моста в бухте Измит

Osman Gazi Bridge Projects

Within the scope of the Osman Gazi Bridge Project; 4 different works; such as diaphragm wall works at South Anchorage Block and South Approach Viaducts, sheet pile driving and extracting works at Dry Dock, soil improvement by jet grouting at North Side Span Pier were successfully completed.

The Osman Gazi Bridge Project is located in one of the most seismically active regions in the world. Since the project alignment intersects with the North Anatolian Fault Line, the design of the structures is of special importance. The fact that the seismic activity of the South Anchor Block area has not lost its activity from the past till today increases the significance of the bridge project in terms of engineering. Especially South Anchorage Block and South Approach Viaducts represent the initials in Turkey in terms of civil engineering.

South Anchor Block

Within the scope of Osman Gazi Bridge Project, South Anchor Block was constructed. Since South Anchorage Block and South Side Span Pier were designed as gravity type integrated structure, the maximum excavation depth of 16.5 m had to be done as a whole on artificial fill area acquired from the sea. Therefore, the geometry of the shoring structure was different from the ones constructed abroad. It was designed by enabling rectangular shoring system to work together with multi-cell shoring system and compatible with the shape of integrated structure. The plan view of the shoring system looks like a guitar in shape. This shoring project is very special not only in Turkey but also in the world. Moreover, this cantilever multi-cell diaphragm wall project has been successfully accomplished for the first time in Turkey.

South Approach Viaducts Diaphragm Wall Works

Diaphragm walls are implemented as a box type deep foundation under the South Approach Viaduct Footing Foundations; which is a part of Izmit Bay Crossing Suspension Bridge Project. Since the project location crosses North Anatolian Fault and it lies on the secondary faulting zone, special techniques were used for design and construction of diaphragm walls in order to install continuous horizontal reinforcement; which is quite different from the traditional methods. Therefore, this project is very special not only in Turkey but also in the world. South Approach Viaducts located at Hersek Peninsula and having a length of 1,378.92m, are founded on 11 nos of footing placed with 125 m of spacing. Height of viaduct footings varies between 13 m to 57 m. Under these footings, total area of 14,700 m² diaphragm walls were constructed.

Viaduct footing foundation system was selected as box type foundation system which consists of monolithically working diaphragm walls having a thickness of 1m and dimensions of 21m x 8m. This foundation system which has been implemented in only a few projects in the Far East and the Middle East, was the most suitable selected foundation system. After the construction of viaduct foundations was completed, Cross Hole Sonic Logging Tests (CSL) in 100 nos of different points were performed for each foundation in order to determine the continuity of diaphragm wall panels through the panel depth by an independent laboratory. Maximum weight of “L” and “T” shaped reinforcement cages were about 40 ton. In order to maintain the rigidity of reinforcement cages of “L” and “T” shaped reinforcement cages, a special lifting frame was designed and produced for this project and cages were lifted with the help of this lifting frame.