Behnam. Eslami, Aliakbar. Golshani

:ABSTRACT

The current study is aimed at investigating the basic soil behavior involved in a TBM-EPB excavation and the capability of the Modify Cam Clay (MCC) model is verified for the analysis of the soil settlement in cohesive soils. Tunnel Excavation in urban areas can engender considerable ground movements, which is known as one of the complicated issues that may have negative effects on the extant structures. In this paper, the construction of the second line of Mashhad metro is considered as a case study. Each section of the ground was modeled by two constitutive models namely MCC and Mohr-Coulomb (MC). Afterwards, the results of numerical analyses and monitoring data were compared with each other. In addition, real parameters of soil such as volume loss and the inflection point were obtained via empirical approaches verified by tunnel monitoring. Numerical modeling was performed by FLAC3D software. Based on the transverse and longitudinal sections settlement, MCC model showed high capabilities of predicting the surface settlement in comparison to MC model. Finally, using MCC model was chosen as a rational strategy to predict the soil behavior especially for soft clay with low pre-consolidation ratio or normal consolidation.

KEYWORDS: EPB -TBM, MCC, MC, Tunnel monitoring, surface settlement

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