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Contour maps of horseshoe-shaped tunnel’s strain and stress. (a) Surfer contour map of σP. (b) Surfer contour map of σθ. (c) Surfer contour map of τρθ . (d) Surfer contour map of ϵρ. (e) Surfer contour map of εθ. (f) Surfer contour map of σρθ.
Source publication
While the tunnel is in the high tectonic stress environment and surrounding rock of tunnel has the characteristics of soft texture and stronger expansion, the preference of tunnel shape is horseshoe. An elastic-plastic model is analyzed by complex function theory in accordance with the deformation characteristics of a horseshoe-shaped tunnel in an...
Citations
... It can be concluded that the stress concentration of the surrounding rock is closely related to the strike of the rock stratum until rockburst. In other words, rockburst is closely related to the direction of tectonic stress [44,45]. In addition to geological factors, mining conditions and construction procedures are also very important factors affecting rockburst. ...
To study the occurrence process, as well as the temporal and spatial evolution laws, of rockburst disasters, the roof deformation of continuous heading roadways during rockburst was studied through a physical similarity simulation test with a high similarity ratio and low strength. The deformation and failure evolution law of the roadway roof in the process of rockburst were analyzed by using detection systems, including a strain acquisition system and a high-power digital micro-imaging system. The results show that the rockburst of the roadway roof can be divided into four stages: equilibrium, debris ejection, stable failure, and complete failure stage. According to the stress state of a I–II composite crack, the theoretical buckling failure strength of the surrounding rock is determined as 1.43 times the tensile strength. The flexural failure strength of a vanadium-bearing shale is 1.29–1.76 times its compressive strength. With continuous advancement in the mining time, the internal expansion energy of the roadway roof-surrounding rock in the equilibrium stage continuously accumulates. The fracture network continuously increases, developing to the stable failure stage, with bending deformation, accompanied by continuous particle ejection until the cumulative stress in the failure stage increases, and the tensile state of the rock surrounding the roof expands radially into deep rock. A microscopic damage study in similar material demonstrated that the deformation of the roadway roof is non-uniform and uncoordinated. In the four stages, the storage deformation of the rock surrounding the roadway roof changes from small accumulation to continuous deformation, to the left (or deep rock). Finally, the roadway roof-surrounding rock becomes completely tensioned. The research results presented in this study provide a reference for the prediction and control of rockburst in practical engineering.
Examining the modal analysis of an integrated structure consisting of a box-girder bridge and a tunnel with a railroad track is critical for ensuring structural integrity, safety, and functionality, especially concerning resonance with time-varying external forces such as vehicle and seismic loads. Prior studies have indicated that modal analysis of this kind of integrated system has received little attention. The key objective of this research is to determine the natural frequency and mode shape of this integrated system. The free vibration analysis of the FEM model of the integrated system is carried out by the FEM software, ANSYS. The modal character parameters of the present model are investigated by comparing free vibration analysis with and without a railway track. The natural frequencies of this model without the railway track system were reduced as an outcome of a decrease in model stiffness.
