Engineering geology of the tunnel route between Üçyol district and Fahrettin Altay public square

The tunnel cross-section is 5,2 km long the second phase of the İzmir metro passing through the between the Üçyol District and Fahrettin Altay Public square of the city. There are 5 stations on the route those which the platform of Hatay, Göztepe and Poligon stations are tunnels, ticket halls are cut-and-cover, Fahrettin Altay station is hybrid system, İzmirspor station and the spaces between stations are tunnel excavations. Within the scope of this study, in order to form a base for "Engineering Geology" initially general geology of the route is summarized. For this purpose, previous studies on this area by different researchers and tunnel-scarp sections at certain intervals prepared by engineers working in metro during the excavations are utilized; furthermore, by personel investigations in the tunnel the lithological and structural properties of the route were outlined. As a part of the engineering geological studies, the result of the laboratory test performed on the core samples belong to the boreholes of subsurface investigation undergone previously and geotechnical data on the tunnel scrap sections were utilized; furthermore geological and hydrogeological measurements and observations were done. Weathering states and rock quality designation of the rocks present in tunnel excavation cross-section were examined, the laboratory test results belonging to some physical (dry unit weight, saturated unit weight, porosity) and mechanical (uniaxial compressive strength, point load and tensile strengths) properties of the units forming the route were evaluated statistically. Besides, the hydrogeological environment in the second phase of the İzmir metro, water table level and the variations of water coming through the tunnel depending on the geological properties of rock mass were investigated. After that, rock mass classifications (NATM, RMR, GSI and Q systems) of the units belonging to the Yamanlar Volcanites and Altındağ Formation were done. The tunnelling technics (New Austrian and New Italian) and tunnel support systems were outlined, tunnel types and rock mass classification systems used in the study and their properties were explained as being a base for the numerical modelling. In the numerical modelling chapter, the numerical modelling was done for 5 different zones determined in the tunnels excavated in the work of İzmir second phase metro project by Phase2 (v.07) software; the stresses active on the tunnel cross-section, deformations (permanent ground deformations) and related total displacements were computed and the results were evaluated. Three of these zones are of the andesites present in the Yamanlar Volcanites, two of them to claystone-siltstone-sandstone-conglomerate intercalation forming the Altındağ Formation. Models were formed due to the different weathering degrees (slightly, moderately and highly weathered), evaluated in the case of supported and unsupported conditions, after that, whole model was examined under the seismic loadings of 0.1g and 0.15g, seperately. As a result, 90 different model were derived from these 5 zones.