Equivalent gas aperture of rock fracture: Theoretical model and experimental validation

IF 7.5 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

International Journal of Rock Mechanics and Mining Sciences Pub Date : 2025-06-25 DOI:10.1016/j.ijrmms.2025.106186

Yaoyao Zhao, Zhihong Zhao, Yunzhe Jin

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引用次数: 0

Abstract

Fractures are the main channels for fluid and gas flow in rock masses. Hydraulic aperture, which is derived for an incompressible fluid, is commonly employed to characterize flow properties of rock fractures. However, hydraulic aperture may not be suitable for describing the gas flow behavior through rock fracture when considering gas compressibility and slippage. Therefore, a new concept of gas aperture is proposed to characterize gas flow properties of rock fractures, and its definition and determination procedure are provided. A number of gas flow tests on granite fractures with flat or rough surfaces are conducted under varying confining and gas pressures. The results show that hydraulic apertures can underestimate gas apertures by 5–30 % when the ratio of the gas pressure difference between inlet and outlet to the mean gas pressure exceeds 0.25. Finally, an empirical formula is developed to describe the relationship between mechanical and gas apertures. This study advances understanding of gas flow behavior in rock fractures through the novel gas aperture concept, overcoming the limitations of hydraulic aperture in gas flow scenarios and enabling enhanced predictive modeling of gas transport in fractured rock masses.

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岩石裂隙等效瓦斯孔径：理论模型与实验验证

裂隙是岩体中流体和气体流动的主要通道。水力孔径是针对不可压缩流体导出的，通常用于描述岩石裂缝的流动特性。然而，考虑到气体的可压缩性和滑移性，水力孔径可能不适合描述岩石裂隙中气体的流动行为。为此，提出了表征岩石裂隙气体流动特性的气体孔径概念，并给出了其定义和确定方法。在不同围压和气体压力下，对具有平坦或粗糙表面的花岗岩裂缝进行了大量的气体流动试验。结果表明，当进出口气体压力差与平均气体压力之比超过0.25时，液压孔径可低估气体孔径5 ~ 30%；最后，建立了一个经验公式来描述力学和气体孔径之间的关系。该研究通过新的气体孔径概念推进了对岩石裂缝中气体流动行为的理解，克服了水力孔径在气体流动场景中的局限性，增强了对裂隙岩体中气体输运的预测建模。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

International Journal of Rock Mechanics and Mining Sciences 工程技术-工程：地质

CiteScore

14.00

自引率

5.60%

发文量

196

审稿时长

18 weeks

期刊介绍： The International Journal of Rock Mechanics and Mining Sciences focuses on original research, new developments, site measurements, and case studies within the fields of rock mechanics and rock engineering. Serving as an international platform, it showcases high-quality papers addressing rock mechanics and the application of its principles and techniques in mining and civil engineering projects situated on or within rock masses. These projects encompass a wide range, including slopes, open-pit mines, quarries, shafts, tunnels, caverns, underground mines, metro systems, dams, hydro-electric stations, geothermal energy, petroleum engineering, and radioactive waste disposal. The journal welcomes submissions on various topics, with particular interest in theoretical advancements, analytical and numerical methods, rock testing, site investigation, and case studies.