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Geomechanics and Engineering
  Volume 17, Number 1, January20 2019 , pages 97-107

An improved collapse analysis mechanism for the face stability of shield tunnel in layered soils
Guang-hui Chen, Jin-feng Zou and Ze-hang Qian

    Based on the results of Han et al. (2016), in the failure zone ahead of the tunnel face it can be obviously identified that a shear failure band occurs in the lower part and a pressure arch happens at the upper part, which was often neglected in analyzing the face stability of shield tunnel. In order to better describe the collapse failure feature of the tunnel face, a new improved failure mechanism is proposed to evaluate the face stability of shield tunnel excavated in layered soils in the framework of limit analysis by using spatial discretization technique and linear interpolation method in this study. The developed failure mechanism is composed of two parts: i) the rotational failure mechanism denoting the shear failure band and ii) a uniformly distributed force denoting the pressure arch effect. Followed by the comparison between the results of critical face pressures provided by the developed model and those by the existing works, which indicates that the new developed failure mechanism provides comparatively reasonable results.
Key Words
    face stability; shield tunnel; layered soils; limit analysis; pressure arch effect
Guang-hui Chen, Jin-feng Zou and Ze-hang Qian: School of Civil Engineering, Central South University, No.22, Shaoshan South Road, Central South University Railway Campus, Changsha, Hunan Province, People

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