Geotechnical consideration regarding the routing of twin railway tunnels across the Karoun river

Abstract

Ahwaz city is located in the Khoozestan Province, a floodplain, almost flat area on the south western margin of the Zagros mountain range, well known by its giant oil fields. The four main geological phenomena of this area are: the Ahwaz fault, the Ahwaz anticline, the Aghajari formation and the alluvium deposits of Quaternary. Karoun, the biggest river of Iran, runs through this city. The Ahwaz Urban Railway Project was started in 2006 (the engineering, procurement and construction (EPC) contractor is Kayson Company). About 100 bore holes were drilled along the project, and the main problem was how to cross the river. Due to the city condition (streets, buildings...) the tunnels should pass under the river, but where and at what depth is the question. The agglomeration of people and transportation system were dictated by the zone of river crossing but in order to find the exact location and depth of the tunnels, complete studies were undertaken. © 2012 WIT Press.