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Experimental study of the shear behavior of carbonate bedding planes cemented by different materials |
ZHOU Yangyi1,FENG Xiating1,XU Dingping1,LI Shuaijun1,CHEN Dongfang2 |
(1. State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;2. Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines,Northeastern University,Shenyang,Liaoning 110819,China) |
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Abstract Bedding planes are of significant importance for the stability of layered rock mass. In order to perform detailed stability analysis for underground excavations in layered rock mass,it is necessary to gain sufficient knowledge of shear behavior and strength of bedding planes. Due to the complex physical and chemical processes involved during diagenesis,bedding planes exhibiting different geological features(cementation,roughness,etc) are often seen in a specific engineering site. In order to better characterize the shear behavior of these bedding planes,two types of shear tests,namely the constant normal stress tests and the post-peak stepwise-decreasing normal stress tests,were conducted using the cemented bedding plane samples obtained from underground caverns of Wudongde hydropower station. Test results showed that obviously different shear behavior corresponded to different geological features. The curves of shear displacement-shear stress were mainly divided into two groups according to their peak and residual behavior. The roughness and surface materials of groups with clear peak shear stress were different from the ones without peak. Direct relationship existed between the normal stiffness and normal stress,however,no obvious correlation was found between the normal stiffness and bedding plane types. Dilation behavior and the corresponding dilation angles of different kinds were also observed. The shear strength of cemented bedding planes is higher than the one of the separated bedding planes and lower than the one of the intact rock,which weakens the whole rock mass. A deeper understanding of rock mass behavior can be achieved when the geological variety of bedding planes is properly considered.
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[10] |
PLESHA M E. Constitutive models for rock discontinuities with dilatancy and surface degradation[J]. International Journal for Numerical and Analytical Methods in Geomechanics,1987,11(4):345-362.
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