Geotechnical site investigation for EPB-TBM tunneling in soft ground (Case study: southern extension lot of the Tehran metro Line ۶, Iran)

Identification of the geotechnical properties along the tunnel has an effectual influence for a successful excavation with EPB-TBM machines. The geotechnical information is applied for TBM selection in the pre-construction stage and their mechanical specification, the value of foam agent for soil conditioning in the work face, the accomplishment of the optimum TBM performance, optimal earth pressure balance control, and proper planning of a tunnel. In this study, the geotechnical ground characterization, including soil grouping system (USCS), soil types distribution, and geotechnical risks, is investigated in Tehran alluvial along the southern extension section metro line ۶. The soil materials on the work face along the tunnel have been divided into four engineering geological units based on physical and engineering characteristics. According to the results, most sections along the tunnel are reposed in the stiff category based on the consistency index, cavity limit pressure in the Pressuremeter test, and SPT. ۵۰% of the whole sections have medium clogging risks and moderate to high abrasiveness in the LCPC test.

کلیدواژه ها:

Engineering geological investigation ، EPB-TBM ، soft ground