Evaluation of the Heading Confinement Pressure Effect on Ground Settlement for EPBTBM Using Full 3D umerical Analysis

  • سال انتشار: 1392
  • محل انتشار: مجله بین المللی معدن و مهندسی زمین، دوره: 47، شماره: 1
  • کد COI اختصاصی: JR_IJMGE-47-1_002
  • زبان مقاله: انگلیسی
  • تعداد مشاهده: 372
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نویسندگان

Amir Hossein Haghi

National Iranian South Oilfields Company, Ahvaz, Iran

Mohammad Reza Asef

Geology Department, Kharazmi University, Tehran, Iran

Ali Taheri

Zaminfanavaran Geotechnical Consulting Engineers (ZAFA), Esfahan, Iran,

Mohsen Mohkam

Ecole National des Travaux Publics de L’Etat (ENTPE), Laboratoire Geomateriaux, France

چکیده

Ground settlement is often the most serious concern when tunneling under an old city with numerous historic monuments. A successful engineering design under these conditions would require getting the most out of the ground strength parameters and avoiding any weakening maneuver throughout the operation. Knowing that surface settlement is highly affected by tunneling parameters in EPB shield tunneling lead us to estimate the optimum values for the machine heading pressure with the lower amount of the ground settlement in fragile structure of the old city for the Esfahan Subway Project. Tunnels were dug underneath some of the most prominent historical sites along the path of the project. To improve precision and efficiency in tunneling operation, at the first step, tunnel heading confinement pressure is calculated by using an advanced 3D mathematical approach based on the limit equilibrium theory. Then, a promoted 3D finite element model is developed, taking into account the tunneling procedures and the designed heading confinement pressure from the first step. Settlements were pre-calculated and the surface displacement was checked at all sensitive locations. At the third step, settlement is estimated by exerting executed face supporting pressure to the tunnel face and the concluded amounts for displacement are compared with the outputs of extensometers. This comparison leads us to check the reliability of calculated settlements and the accuracy of the designed tunnel heading confinement pressure. Furthermore, evaluating the relation between extensometer outputs and executed tunnel face pressure at the points of extensometers stations validates the assumption that the safe face supporting pressure causes least surface displacement. Although the minimum pressure occurred in short term fluctuations, this approach confirms the sensibility of settlement with the least executed face supporting pressure.. It is also found that higher executed face supporting pressures could reduce the tunnel face stability. Therefore, documentation of appropriate software facilitates design procedures. Yet a further achievement of this study concerns effective decision implementations under strictly limited.

کلیدواژه ها

EPB shield tunneling machine, extensometer, heading confinement pressure, numerical modeling settlements

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