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Geomechanics and Engineering
  Volume 24, Number 3, February10 2021 , pages 253-266

Designing an innovative support system in loess tunnel
Zhichao Wang, Yuan Xie, Jinxing Lai, Yongli Xie, Xulin Su, Yufeng Shi and Chunxia Guo

    The sufficient early strength of primary support is crucial for stabilizing the surroundings, especially for the tunnels constructed in soil. This paper introduces the Steel-Concrete Composite Support System (SCCS), a new support with high bearing capacity and flexible, rapid construction. The bearing characteristics and construction performance of SCCS were systematically studied using a three-dimensional numerical model. A sensitivity analysis was also performed. It was found that the stress of a π-shaped steel arch decreased with an increase in the thickness of the wall, and increased linearly with an increase in the rate of stress release. In the horizontal direction of the arch section, the nodal stresses of the crown and the shoulder gradually increased in longitudinally, and in the vertical direction, the nodal stresses gradually decreased from top to bottom. The stress distribution at the waist, however, was opposite to that at the crown and the shoulder. By analyzing the stress of the arch section under different installation gaps, the sectional stress evolution was found to have a step-growth trend at the crown and shoulder. The stress evolution at the waist is more likely to have a two-stage growth trend: a slow growth stage and a fast growth stage. The maximum tensile and compressive stresses of the secondary lining supported by SCCS were reduced on average by 38.0% and 49.0%, respectively, compared with the traditional support. The findings can provide a reference for the supporting technology in tunnels driven in loess.
Key Words
    loess tunnel; steel-concrete composite support system; tunneling; mechanical property; stress distribution
Zhichao Wang, Jinxing Lai, Yongli Xie, Xulin Su and Yufeng Shi: School of Highway, Chang'an University, Xi'an 710064, China

Yuan Xie: 1.) Powerchina Xibei Engineering Corporation Limited, Xi'an 710065, China
2.) Institute of Geotechnical Engineering, Xi'an University of Technology, Xi'an 710048, China

Chunxia Guo: School of Science, Xi'an University of Architecture and Technology, Xi'an 710055,

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