Examination of uncertainties and risk sources in Dudullu-Bostanci (Istanbul) Metro construction

Uncertainties in tunnel projects show differences from other engineering projects due to their high variability in geological, hydrogeological, seismic, and geotechnical properties. Engineering geology, geophysical, and geotechnical parameters are needed to minimize these uncertainties. Construction of the Dudullu-Bostanci Metro is being carried out in the Asian section of Istanbul, which passes under the densely populated area from north to south. Earth pressure machines (EPB-TBMs) with a diameter of 6.57 m involve the construction of 14.3 km of Dudullu-Bostanci underground metro line and its 13 stations at an average depth of approximately 30 m. Increasing priority is given to large-scale engineering projects, such as tunnels, where uncertainty is a major risk factor. The aim of this study is to examine the uncertainties and risk sources in Dudullu-Bostanci Metro Line. As a result of uncertainty and risk assessments, tunneling with EPB-TBM method is applied in tunnel excavation, which is determined as the most appropriate method.