Stability Analysis of a Station-TBM Tunnel Intersection Applying Innovative Techniques
Mona A. Mansour1, Amal N. Mohamed2
1Mona A. Mansour*, Civil Engineering Department, Helwan University, Cairo, Egypt.
2Amal N. Mohamed, Egyptian Russian University, Cairo, Egypt (ERU).

Manuscript received on January 05, 2020. | Revised Manuscript received on January 25, 2020. | Manuscript published on January 30, 2020. | PP: 3886-3894 | Volume-8 Issue-5, January 2020. | Retrieval Number: E6603018520/2020©BEIESP | DOI: 10.35940/ijrte.E6603.018520

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Abstract: Tunnel construction using a tunnel boring machine TBM may encounter a coordination difficulty where the machine may reach the station site before the station completion. A construction solution for such a station-TBM intersection is vital. In the Cairo Metro Tunnel-Line 3, Heliopolis station, infrequent construction sequence was adapted, where the station transverse diaphragm walls were firstly installed to let the tunnel boring machine entering the station vicinity and erecting the tunnel lining within and after the station. Afterward, the longitudinal diaphragm walls of the station were installed parallel to the tunnel line. In view of that, the tunnel parts enclosed by the station were required to be safely demolished, followed by completing the remaining station elements. The process of removing the lining segments within the station involves a risk of instability of the existing tunnel because of excessive deformations. Therefore, innovative four construction techniques were suggested and numerically inspected to find an optimal sequence of executing such a hard construction condition. Numerical models, established by the 2-D finite element software, PLAXIS, were adopted in a staged analysis to simulate the construction phases till the critical phase of removing the tunnel segments, where the tunnel stability was considerably reduced. At that point, stability analysis was performed to examine the liability of the four demolishing scenarios. These scenarios include partial filling the tunnel with sand at the demolishing location, and/or using internal or external link members. Lastly, the optimal technique to remove the lining segments inside the station considering stability, economy and time-saving, was decided.
Keywords: Diaphragm Wall, Intersection, PLAXIS, Station, Stability Analysis, TBM Tunnel.
Scope of the Article: Image Analysis and Processing.