Nonlinear deformation and failure characteristics of horseshoe-shaped tunnel under varying principal stress direction

Abstract

To reveal the nonlinear deformation characteristics and failure mechanisms of surrounding rocks of horseshoe-shaped tunnel affected by varying principal stress directions, the physical experiments are carried out based on the similarity theory and control variable method. Simultaneously, on the basis of the statistical strength theory and meso-damage mechanics, a series of 2D numerical models which are able to consider the rock heterogeneity are established to further investigate the mechanical mechanism of damage evolution of surrounding rocks. Seven different kinds of horseshoe-shaped tunnel models are tested and the typical failure modes are analyzed according to the experimental data and numerical simulations. The results show that when the lateral pressure coefficient is small, fractures mainly develop towards the remote maximum principal stress direction; when the pressure difference between the vertical and horizontal directions is small, tunnel surrounding rocks damage seriously; initial damage of surrounding rocks basically occurs at the bottom floor corners and arch shoulders; the process of stress buildup, shadow and transfer is the fundamental mechanical process for the formation of mesoscopic damage and macroscopic failure.Overall, these achievements can provide valuable insights into the nonlinear failure mechanisms of horseshoe-shaped tunnel and will contribute to tunnel support design and stability evaluation in geotechnical engineering.

Anisotropic mechanical response of layered shales: Insights from numerical simulations

“…By introducing the heterogeneity coefficient to characterize the heterogeneity of rock material, it can simulate the redistribution of stress field and the induced creation and evolution of microfractures (Gong et al, 2022a;Wang et al, 2022c;Yu et al, 2022). It has been applied to numerically reproduce the gradual failure process of rock material by many researchers (Chen et al, 2022b;Gong et al 2019b;Gong et al 2022b). Compared with the traditional finite element method, the RFPA method has three main characteristics: (I) The heterogeneity of rock material can be considered, and the nonlinear deformation and failure process of rock material can be simulated on the basis of the elasto-brittle-plastic constitutive model; (II) Each representative volume element will maintain the linear deformation state until the element stress satisfies the strength criterion.…”

Numerical Investigation on Anisotropy and Shape Effect of Mechanical Properties of Columnar Jointed Basalts Containing Transverse Joints

“…Additionally, the effectiveness of RFPA has been verified by many benchmarks (Xu et al 2021;Wang et al 2022). Meanwhile, RFPA has been applied in the stability assessment (Chen et al 2022;Gong et al 2022a), failure mechanism (Zhou et al 2018;Gong et al 2022b) and instability precursor (Liu et al 2017;Zhang et al 2021) of rock mass.…”

Dynamic failure characteristics of surrounding rocks under different lateral pressure coefficients in deep tunnel transient excavation

“…Yi et al ( 2020 ) investigated the progressive fracture processes around tunnels triggered by blast disturbances under different lateral pressure coefficients and found that the influence of the disturbance is the smallest when the lateral pressure coefficient is 1.0. In addition, the shape of the tunnel (Zhong et al 2018 ; Gong et al 2022a , b ), the excavation methods (Falls and Young 1998 ; Yang et al 2013 ) and the external disturbance (Jiang et al 2018 ; Jian-po et al 2020 ; Yi et al 2020 ) may also influence the formation of the EDZ.…”

“…Also, the existing laboratory experimental methods cannot reproduce the tunnels’ real stress loading/unloading path (Sun et al 2021 ), especially for those excavated by D&B. The overloading tests were often conducted on the specimens with a prefabricated circular hole (Pan et al 2020 ; Yi et al 2020 ; Gong et al 2022a , b ; Zhang et al 2022 ) or by excavating a hole in an intact rock mass under pre-stress (Yang et al 2018 ; Li et al 2019 ; Abierdi and Xiang 2020 ; Zhu et al 2020 ; Xiang et al 2021 ; Askaripour et al 2022 ; Gong et al 2022a , b ; Hao et al 2022 ; Zhu et al 2022a , b ). For model tests without an overloading procedure (Sun et al 2018 ; Xu et al 2021 ; Wang et al 2022 ), the EDZ is not as significant as expected, and thus the deformation and the stress redistribution of the surrounding rock masses are mainly discussed.…”