Experimental Study on Hydro-mechanical Behaviour of Anisotropic Columnar Jointed Rock-Like Specimens
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ORIGINAL PAPER
Experimental Study on Hydro‑mechanical Behaviour of Anisotropic Columnar Jointed Rock‑Like Specimens Zhipeng Xiang1 · Huanling Wang2 · Weiya Xu1 · Wei‑chau Xie3 Received: 12 August 2019 / Accepted: 5 September 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Columnar jointed rock masses (CJRM), characterized by regular arrays of polygonal prisms or columns, are exposed in the dam foundation of the Baihetan hydropower station and pose a challenge to the stability of the project. To understand the hydro-mechanical behaviour of Baihetan CJRM, triaxial compression experiments are carried out on artificial CJRM specimens with regular arrays of hexagonal columns, which are similar to the actual CJRM. Based on the experimental results, mechanical and hydraulic behaviour of CJRM is studied. It is found that the compressive strength of CJRM varies in a typical U-shape with the joint inclination angle. Three failure modes associated with the angle of joint inclination are observed. The evolution of permeability with stress exhibits distinct phased characteristics: initial compression stage, linear elastic stage, yield stage, and strain-softening stage. The results of this study provide helpful information for the design and construction of the Baihetan project involving CJRM. Keywords Columnar jointed rock masses · Hydro-mechanical coupling · Anisotropic characteristics · Permeability evolution List of Symbols 𝛽 Angle of joint inclination K Permeability K0 Initial permeability 𝜇 Water dynamic viscosity L Length of flow path Δt Time interval
* Huanling Wang [email protected] Zhipeng Xiang [email protected] Weiya Xu [email protected]
ΔV Volume change of water pump within each time interval A Cross-sectional area of rock specimen Δp Hydraulic pressure difference between the top and the bottom of the specimen 𝜎i Peak deviatoric strength of columnar jointed specimen 𝜎c Peak deviatoric strength of intact specimen Re Reduction parameter E50 Deformation modulus Es Elastic modulus 𝜀1 Axial strain 𝜀3 Radial strain 𝜀v Volumetric strain
Wei‑chau Xie [email protected]
1 Introduction
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The presence of joints greatly affects the mechanical behaviour of rock masses (Bobet 2000; Gehle and Kutter 2003; Hoek and Martin 2014; Lee et al. 2017). Columnar joints are characterized by regular or irregular polygonal arrays. The intact rock mass is cut by columnar joints into rock blocks, resulting in weak jointed rock masses (Fig. 1). Columnar jointed rock masses (CJRM) are commonly found in
Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, Jiangsu, China
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Key Laboratory of Ministry of Education for Coastal Disaster and Defense, Hohai University, Nanjing 210098, Jiangsu, China
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Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON N2L3G1, Canada
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Fig. 1 Columnar jointed rock masses at the Baihetan hydropower station
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