Estimation of Geotechnical Parameters by Comparing Monitoring Data with Numerical Results: Case Study of Arash–Esfandiar-Niayesh Under-Passing Tunnel, Africa Tunnel, Tehran, Iran

The under passing tunnels are strongly influenced by the soils around. There are some complexities in the specification of real soil behavior, owing to the fact that lots of uncertainties exist in soil properties, and additionally, inappropriate soil constitutive models. Such mentioned factors may cause incompatible settlements in numerical analysis with the obtained values in actual construction. This paper aims to report a case study on a specific tunnel constructed by NATM. The tunnel has a depth of 11.4 m, height of 12.2 m, and width of 14.4 m with 2.5 lanes. The numerical modeling was based on a 2D finite element program. The soil material behavior was modeled by hardening soil model. According to the field observations, the numerical estimated settlement at the ground surface was approximately four times more than the measured one, after the entire installation of the initial lining, indicating that some unknown factors affect the values. Consequently, the geotechnical parameters are accurately revised by a numerical back-analysis using laboratory and field test data and based on the obtained monitoring data. The obtained result confirms that typically, the soil parameters are conservatively low-estimated. And additionally, the constitutive models cannot be applied properly for all soil conditions.

• Aliakbar Golshani
• Seyyed Mehdi Poorhashemi
• Mahsa Gharizadeh

• NATM tunnel
• initial lining
• field test data
• laboratory test data
• monitoring data
• numerical back-analysis.

[1] Wang, Lei, "Probabilistic Back Analysis of Geotechnical Systems" (2013). All Theses. Paper 1727.
[2] Design and construction of road tunnels (FHWA-NHI-10-034), December 2009.
[3] The British Tunnel Society and Institution of Civil Engineers, “Tunnel Lining Design Guide”, Thomas Telford Ltd., 2004.
[4] Brinkgreve, R. B. J., Broere, W., Waterman; D, PLAXIS 2D- Version 8.
[5] T. Schanze, P. A. Vermeer, P. G. Bonnier, "The hardening soil model: formulation and verification", Beyond 2000 in Geotechnical Geotechnics, ten years of PLAXIS, 1999 Balkema, Rotterdam, ISBN 90 5809 040X.
[6] ACI 318-99, Building Code Requirements for Structural Concrete and Commentary.