Bedding Plane Effects on Mechanical Behavior of Surrounding Rock in Mountain Tunneling

Shuang You,Jincui Sun,Hongtao Wang,Fan Feng

doi:10.1155/2021/7346061

Shuang You, Jincui Sun + Show 2 more

Open Access

https://doi.org/10.1155/2021/7346061

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Abstract

The layered rock showed the characteristics in Mountain tunnel, Yunnan. A series of uniaxial compression tests and variable angle shear tests were carried out, and the aim was to investigate the effect of the bedding on its mechanical parameters and failure modes. The test results show that the uniaxial compressive strength, elastic modulus, and Poisson's ratio of layered rock present a U-shaped distribution with the increase in bedding orientation from 0° to 90°. All of them have a maximum when the bedding orientation is 0° and a minimum when the bedding orientation is 45°. The failure modes of layered rock can be summarized into three types: the fracture tensile failure parallel to the weak plane of bedding; the shear slip failure along bedding weak plane; and tension-shear composite failure between bedding weak plane and matrix. Based on the testing data and analysis results, it can be concluded that the layered rock specimen with different bedding orientations is an important reason for the anisotropy of mechanical parameters and failure modes.

Highlights

Rough the uniaxial compression test and variable angle shear test, the variation law of peak strength and mechanical parameters of layered rocks with different bedding orientations was explored, and the failure modes were classified and analyzed
Cohesion Internal friction angle bedding plane; when the bedding orientation is 30°, the shear failure along the weak bedding plane and through the bedding plane occurs; when the bedding orientation is 60°, the shear slip failure along the weak bedding plane occurs, and the ends present the phenomenon of crossing the matrix; when the bedding orientation is 90°, the splitting tensile failure along the weak bedding plane occurs, and the failure surface is relatively regular
The variation trend of both is similar to the compressive strength of layered rock

Summary

Experimental Tests

In order to study the anisotropic characteristics of rock mass under different bedding orientations, core drilling sampling was carried out from five directions of 0°, 30°, 45°, 60°, and 90°, respectively. E uniaxial compression test and variable angle shear test were carried out on cylinder specimens and cube specimens, respectively.

Analysis of Test Results

Conclusions