Experimental Study on the Full-Field Characteristics of Displacements of a Bedded Limestone by Digital Image Correlation
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ORIGINAL PAPER
Experimental Study on the Full-Field Characteristics of Displacements of a Bedded Limestone by Digital Image Correlation Yang-Yi Zhou
. Xu-Feng Liu . Yan-Hua Gong . Guo-Qiang Zhu
Received: 27 May 2020 / Accepted: 19 November 2020 Ó Springer Nature Switzerland AG 2020
Abstract Rocks with bedding or foliation usually behave as anisotropic body. Understanding the fullfield displacement characteristics of anisotropic rocks is of particular interest, since the behaviors of anisotropic rocks vary with the angle between bedding and loading direction, and are thus more difficult to predict than isotropic rocks. By the digital image correlation technique, the two-dimensional displacement fields of a bedded limestone with different bedding angles are obtained in this paper. Displacement field evolution process with loading is described in detail, in which the progressive rotation of principal strains can be identified. The displacement field pattern also varies with loading angle. If some threshold of loading angle is surpassed, the pattern can transit from one to another, which is essentially determined by the tensor transformation rule of compliance matrix. The non-coaxiality between Y.-Y. Zhou (&) X.-F. Liu Y.-H. Gong Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines, Northeastern University, Shenyang 110819, Liaoning, China e-mail: [email protected] G.-Q. Zhu State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China G.-Q. Zhu University of Chinese Academy of Sciences, Beijing 100049, China
principal strains and stresses with respect to different loading angles are calculated from both test results and numerical simulation, which further confirms the validity of transverse isotropy—a fundamental assumption for rocks exhibiting layered structure. Keywords Anisotropic rock Full-field displacement Digital image correlation Principal strain Non-coaxiality
1 Introduction As natural material with geological origin, rocks in most cases cannot be treated as ideally isotropic body, due to certain mineral composition and arrangement pattern. In other words, the deformation and strength characteristics of rocks often exhibit different degrees of anisotropy. For example, the genesis of sedimentary rocks usually brings about bedding structure, which illustrates as layered or lamellar arrangements of material (minerals or larger fragments) at different scales. As a result, more prominent deformation can often be observed perpendicular to bedding. Besides, fracturing along certain paths and the corresponding strength anisotropy can be associated with various kinds of metamorphic rocks, in which the directional distributions of minerals such as foliation, schistocity, cleavage, etc., are generally developed. Deeper
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Geotech Geol Eng
understanding of the mechanical properties of rocks can be gained by investigating the anisot
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