Geotechnical Challenges of Tehran Metro Line 7 (South Northern Route)

Tunneling in urban areas, has raised the level of difficulty and challenge in respecting the constraints deriving from humanpresence and, therefore, the necessity for the study of geological and geotechnical properties and parameter, classificationof the soils according to their engineering behavior, choosing the right TBM, determine groundwater level and determiningpossible geological hazards. In this paper some geological and geotechnical study took place along the tunnel route. Thisinvestigation is done by the result of 73 machinery borehole and 32 manual borehole that took place in the process ofstudying the tunnel route and continued by the result of field tests and laboratory tests and according to the result, thegeological zone classified in 6 zone in tunnel route; due to the result of Cerchar abrasivity test and since Alluvial soil isthe main soil in most of the tunneling route, the excavation soil classified as highly abrasive. In some part of tunnellingthere is a risk of clogging due to the high amount of clay. Based on the results of Lofran tests the permeability of most ofthe classified soils in route of the tunnel was obtained less that 10E-7 m/s.

Keywords:

Liquefaction Potential Index , Geographic Information System (GIS) , Yangon City , Liquefaction Potential Map , SPT Data