Baek Seungo, Kim Kwang Yeom, Kim Gun, Yun Tae Sup
Department of Civil, Urban, Earth, and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea.
Department of Energy & Resources Engineering, Korea Maritime & Ocean University, Taejong-ro, Youngdo-gu, Busan, 49112, Republic of Korea.
Sci Rep. 2024 Nov 6;14(1):26986. doi: 10.1038/s41598-024-78367-6.
The anisotropic nature of granite, a key factor affecting its mechanical properties, is inherently governed by its mineral alignment and the presence of orthogonal cleavage planes: rift, grain, and hardway. This study examines how these cleavage planes influence anisotropy, particularly in the context of microcracking formation and acoustic properties. A new measurement procedure for the acoustic nonlinearity parameter ([Formula: see text]) is developed to address the well-known limitations of conventional linear ultrasound methods, including wave velocity and attenuation coefficient, in detecting microstructural changes induced by existing cleavage planes. Unlike other parameters, [Formula: see text] exhibits remarkable changes depending on the plane type, highlighting its high sensitivity to the mineral distribution in each cleavage plane and to the microcracks. A correlation between the linear and nonlinear parameters provides further evidence of the superiority of [Formula: see text] in detecting inherent microscale defects that develop in each plane and affect the anisotropic characteristics of granite. The findings of this study confirm that nonlinear ultrasound is capable of elucidating the mechanisms underlying the origin of anisotropy in granite due to microcracks, with broader implications for understanding unidentified chemical and mechanical phenomena in geological materials.
花岗岩的各向异性是影响其力学性能的关键因素，其本质上由矿物排列以及正交解理面（裂隙、纹理和硬路）的存在所决定。本研究探讨了这些解理面如何影响各向异性，特别是在微裂纹形成和声学特性方面。开发了一种用于声学非线性参数（[公式：见原文]）的新测量程序，以解决传统线性超声方法（包括波速和衰减系数）在检测由现有解理面引起的微观结构变化方面的众所周知的局限性。与其他参数不同，[公式：见原文]根据平面类型表现出显著变化，突出了其对每个解理面中矿物分布和微裂纹的高敏感性。线性和非线性参数之间的相关性进一步证明了[公式：见原文]在检测在每个平面中形成并影响花岗岩各向异性特征的固有微观缺陷方面的优越性。本研究结果证实，非线性超声能够阐明由于微裂纹导致花岗岩各向异性起源的潜在机制，这对于理解地质材料中未识别的化学和力学现象具有更广泛的意义。
