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Study on mechanical properties of a layered rock with holes under the support structure
  • +3
  • Jian Tang,
  • Cheng Li,
  • Rui Lei,
  • Fang Yuan,
  • Ling Kong,
  • Jun Teng

Abstract

In order to analyze the action mechanism of the tunnel support structure and its supporting characteristics in a layered and weak rock tunnel, an experimental study on seven types of support situations, namely, rough tunnel, systematic rock bolt support, systematic rock bolt, and shotcrete support, systematic rock bolt and shotcrete and steel arch support, steel pipe support, steel pipe, and shotcrete support, and steel pipe and shotcrete and steel arch support, has been conducted. The mechanical, deformation, and support characteristics of the rock with holes under uniaxial compression tests have been studied. The experimental results demonstrated that (1) all different support structures can enhance the uniaxial compressive strength of the specimens, but different support structures exhibit different effects. The rock bolt can significantly enhance the strength of the specimen, but the supporting effect of concrete and steel arches is not evident. (2) The bedding direction directly affects the strength enhancement of the support structure to the specimen, the support strength of the support structure to the rock with a bedding angle of 90° is higher than that of the rock with a stratification angle of 0°, and the bedding affects the failure process of the rock mass and the secondary crack distribution. (3) By using the CT scan of the specimens after the test, it is found that the bolt’s crack arrest effect on cracks is the result of weakening, shearing, and arresting of cracks in the anchorage zone; the crack arrest effect is related to the size of the anchorage zone, and the larger the range of the anchorage zone, the better the crack arrest effect.