Location
Chicago, Illinois
Date
02 May 2013, 7:00 pm - 8:30 pm
Abstract
The highly inhomogeneous nature of the river deposits in central Esfahan induced unforeseen problems for tunneling of 2×5 km long of middle section of the Esfahan Subway Project. A noticeable phenomenon in these course grained fluvial (river) deposits is the locally cementation of the soil particles by a calcium carbonate binder and formation of some semi-hard to hard conglomerate lenses. This unique phenomenon is named locally as “Sovord” rock and could be seen just in semi-aired regions as central Iran. Two 6.89 m diameter EPBTBM machines were employed to excavate shallow tunnels in the vicinity of fragile structures of the old city. The main unwanted impacts of this highly cohesive pseudo-rock were noticed as high vibration, temperature raising, tunnel face instability, low rate of machine’s advance, early tools damage and finally great cutter-head damage after the first major collision with this unpredicted phenomenon. We analyzed geotechnical characteristics of this material and the corresponding effects on face supporting pressure, foaming agents, soil conditioning process and operational policy. Lowering the cylinder thrust force, ≤9000KN, improving the cutting wheel rotation speed, ≥2.5RPM, using some anti-abrasive foaming agents, ABR2 lubricants, and periodic tools inspection schedule was considered as solution for the indicated problem.
Department(s)
Civil, Architectural and Environmental Engineering
Meeting Name
7th Conference of the International Conference on Case Histories in Geotechnical Engineering
Publisher
Missouri University of Science and Technology
Document Version
Final Version
Rights
© 2013 Missouri University of Science and Technology, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Document Type
Article - Conference proceedings
File Type
text
Language
English
Recommended Citation
Haghi, Amir Hossein; Taheri, Ali; and Haghi, A. Ehsan, "Promotion of Tunneling Performance in Locally Semi-Hard to Hard Conglomerate Lenses, Case of Esfahan Historical City Subway Project" (2013). International Conference on Case Histories in Geotechnical Engineering. 5.
https://scholarsmine.mst.edu/icchge/7icchge/session05/5
Promotion of Tunneling Performance in Locally Semi-Hard to Hard Conglomerate Lenses, Case of Esfahan Historical City Subway Project
Chicago, Illinois
The highly inhomogeneous nature of the river deposits in central Esfahan induced unforeseen problems for tunneling of 2×5 km long of middle section of the Esfahan Subway Project. A noticeable phenomenon in these course grained fluvial (river) deposits is the locally cementation of the soil particles by a calcium carbonate binder and formation of some semi-hard to hard conglomerate lenses. This unique phenomenon is named locally as “Sovord” rock and could be seen just in semi-aired regions as central Iran. Two 6.89 m diameter EPBTBM machines were employed to excavate shallow tunnels in the vicinity of fragile structures of the old city. The main unwanted impacts of this highly cohesive pseudo-rock were noticed as high vibration, temperature raising, tunnel face instability, low rate of machine’s advance, early tools damage and finally great cutter-head damage after the first major collision with this unpredicted phenomenon. We analyzed geotechnical characteristics of this material and the corresponding effects on face supporting pressure, foaming agents, soil conditioning process and operational policy. Lowering the cylinder thrust force, ≤9000KN, improving the cutting wheel rotation speed, ≥2.5RPM, using some anti-abrasive foaming agents, ABR2 lubricants, and periodic tools inspection schedule was considered as solution for the indicated problem.
