One of the most common retaining systems for deep excavations is by supporting a wall with multiple levels of anchors. In densely built urban areas, preventing soil movement with such a system can be very costly. Additionally, anchored walls are assumed and forced to act independently during design calculations, thus fail to take the advantage of the rigidity of the whole system at the corners of the excavation area. An alternative support system that uses the entire system is bracing of the walls with struts. But such a system greatly hinders construction space. In this research, a new type of supporting system has been investigated by performing a parametric study in finite element analyses program. New system is a single ring at each support level, supporting the system at several locations. A comparative study has been undertaken between the conventional systems and the new system in both 2D and 3D. PLAXIS finite element analysis software was used for the analyses. The primary aim was to investigate the structural and geotechnical performance of the arch supported system. The study revealed that the new system provides improvement for specific cases and can be considered as an alternatve support system for such cases.

With the industrial revolution, the world was acquainted with the concept of speed. &bdquo / Speed

Urbanisation and suburban housing development are the foci subjects of this thesis. The process of urbanisation may differ from one country to another in terms of socio-economic and political structures, environmental characteristics and also local features. In this context, housing areas at the urban fringe of Ankara were found to have been developed highly compatible with urban land use theories / but different from the process experienced in developed countries. In this thesis, a different dimension of suburbanisation has been discussed with regards to middle and lower-middle income groups&rsquo / suburban movement. The reasons why lower-middle and lower income residents prefer to live at the urban fringe have been found out. Suburban developments have various opportunities for the households such as larger housing unit due to cheap and available land, better urban services, quiet and clean environment and privacy. However, households living in urban fringe who are relatively from middle and lower-middle income are subject to high transportation cost. It is expected that they make a trade off between lower housing units and greater commuting distances and also many opportunities of living in such a suburb. With regard to these, the process of suburbanisation of middle and lower-middle income groups in Ankara within the boundaries of Sincan and Etimesgut Quarters in terms of their social characters and the features of using their urban space and house is discussed according to plan decisions, house builder and households&rsquo / characteristics, urban development pattern of Turkey and Ankara and then Etimesgut and Sincan, considering the theoretical basis and historical process.

Sub-center formation is closely come out when urban environment started to grow and by decentralization and sub-urbanization process to lower the congestions and increase the efficiency in urban life. Besides, by means of rising problems of the growth in an urban area, there emerged the need to share the central activities within the metropolitan region. The growth followed by creation of new towns in the peripheries. Within that organization of the city, sub-centers started to appear to share the burden of the city centers. In this study, the sub-center evolution will be examined with respect to its relationship to urban growth and development. Hence the sub-center formation will be defined and studied in terms of city center, neighborhood center and shopping center developments of the settlements. The criteria on land-use, planning process, design of the built environment, district and neighborhood centers and policies of revisions in the suburb within world examples will help the study to develop principles for sub-center formation. This will provide us to build up some criteria for the central area especially in New Development areas. After the 1970s, the city of Ankara expanded rapidly and there emerged new development areas of the metropolitan region in the West Corridor. With respect to these, Ankara is analyzed with a new urban development area in that corridor called Batikent. With the help of discussions and analysis on sub-center formation on smaller plots belonging to private and a world example of sub-center development produced by the government, design and planning principles of Sub-center growth and development will be proposed in case of Batikent.