Geotechnical Behavior of Tehran Alluvial Deposits Against Possible Seismic Events

Due to the fast urban developing and construction of surface and sub-surface structures such as several subway lines, requiring the geotechnical studies on these structures is increasingly emphasized. The metropolitan Tehran, in south of the Central Alborz, lying on the set of Quaternary alluvial deposits and surrounded by the active seismic faults such as the Northern Tehran fault in the north and the Parchin and Pishva faults in the south requires investigations to determine the bilateral relationship betweenseismic potential of the peripheral active faults andthe geotechnical characteristics of the alluvial deposits. In this study, using field and laboratory data, geotechnical characteristics of the deposits, material of soil horizons, and different parameters of them along the 27 km length of Tehran 7th subway line have been studied by provided software to calculate: bearing capacity, settlement and liquefaction potential. Based on this study, the members C and D of the Tehran alluvial deposits has relatively high resistance value and measured settlement in all areas is limited to 2.5 cm. The data of SPT indicate any likely occurrence of liquefaction of sand layers in the east - central Tehran during a seismic event.