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Mechanical properties and fracture mode transformation of rocks subjected to asymmetric radial stresses
Abstract Based on the analysis of the radial stress distribution in surrounding rocks of tunnel, different asymmetric radial stresses were loaded, which can more truly reflect the stress state of surrounding rocks of tunnel. The stress state and boundary conditions of representative surrounding rock element were simulated by sandstone in this study. The mechanical response and fracture mode transformation were studied. The experimental results showed that as the depth of surrounding rocks from the free surface of tunnel increased, the properties of surrounding rocks showed the characteristics of transition from brittleness to ductility. The strengths of sandstone specimens gradually increased with the increase of the depth, and a power function can well characterize the relationship between the strength and the depth. The fracture modes of sandstone specimens transformed from tensile splitting fracture to tensile-shear complex fracture, and finally to shear fracture with the increase of the depth, which was mainly caused by the asymmetric radial stresses. According to the characteristics of fracture modes under different asymmetric radial stress conditions, four types of failure zones in the radial direction of surrounding rocks can be divided, i.e., tensile splitting failure zone, tensile-shear complex failure zone, shear failure zone, and slight shear failure zone. The shear fracture in deep surrounding rocks and the accompanying large deformation of surrounding rocks should be paid more attention in the support of tunnel. In addition, the accuracy of time-failure model was verified, and it can accurately predict the time needed for rock failure.
Mechanical properties and fracture mode transformation of rocks subjected to asymmetric radial stresses
Abstract Based on the analysis of the radial stress distribution in surrounding rocks of tunnel, different asymmetric radial stresses were loaded, which can more truly reflect the stress state of surrounding rocks of tunnel. The stress state and boundary conditions of representative surrounding rock element were simulated by sandstone in this study. The mechanical response and fracture mode transformation were studied. The experimental results showed that as the depth of surrounding rocks from the free surface of tunnel increased, the properties of surrounding rocks showed the characteristics of transition from brittleness to ductility. The strengths of sandstone specimens gradually increased with the increase of the depth, and a power function can well characterize the relationship between the strength and the depth. The fracture modes of sandstone specimens transformed from tensile splitting fracture to tensile-shear complex fracture, and finally to shear fracture with the increase of the depth, which was mainly caused by the asymmetric radial stresses. According to the characteristics of fracture modes under different asymmetric radial stress conditions, four types of failure zones in the radial direction of surrounding rocks can be divided, i.e., tensile splitting failure zone, tensile-shear complex failure zone, shear failure zone, and slight shear failure zone. The shear fracture in deep surrounding rocks and the accompanying large deformation of surrounding rocks should be paid more attention in the support of tunnel. In addition, the accuracy of time-failure model was verified, and it can accurately predict the time needed for rock failure.
Mechanical properties and fracture mode transformation of rocks subjected to asymmetric radial stresses
Zhao, Honggang (Autor:in) / Gun, Huang (Autor:in) / Jiang, Changbao (Autor:in) / Liu, Chao (Autor:in)
2022
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
BKL:
56.00$jBauwesen: Allgemeines
/
38.58
Geomechanik
/
38.58$jGeomechanik
/
56.20
Ingenieurgeologie, Bodenmechanik
/
56.00
Bauwesen: Allgemeines
/
56.20$jIngenieurgeologie$jBodenmechanik
RVK:
ELIB18
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