Assessment of the reinforced tunnel face stability in sand soils

For the Taidacun tunnel of Yumo railway, combined with theory of Proctodyakonov’s pressure arch and the three-dimensional rotational failure mechanism, an improved three-dimensional rotational failure model with considering soil arching effect was proposed to investigate the tunnel face stability in sand soils. The proposed failure mechanism could be divided into two parts: (1) the rotational failure part in the crossed layer; (2) the arching failure part in the cover layer. Based on the proposed failure mechanism, the soil-anchor model was used to study the stability of reinforced tunnel faces. The results show that: (1) compared with the existing research results, the proposed method is reliable and more suitable for the stability analysis of tunnel faces in sand soils; (2) Combined with the practical tunnel engineering, it can be seen that the method proposed in this study can effectively guide the design and construction of tunnel face reinforcement in sandy soils. © 2021, Central South University Press. All rights reserved.