编号：CDUT-2024-6

标题：Impact of stress-driven crack growth on the emergence of anomalous transport in critically connected natural fracture networks

入藏号：WOS:001049618900001

中国科学院文献情报中心期刊分区：工程技术1区TOP（2023）

本校作者：王晓光；刘礼军

来源出版物：INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES  卷: 170  文献号: 105532

出版年：2023

第一地址：成都理工大学

关键词：In -situ stress; Critically connected natural fracture networks; Shear dilation; Crack growth; Anomalous transport

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摘要：We study the role of in-situ stresses in fluid flow and mass transport through a two-dimensional fractured rock. The fracture network is based on a real outcrop with a connectivity state around the percolation threshold. We simulate stress-dependent fracture propagation and deformation using a geomechanics model based on the hybrid finite-discrete element method. The hydrodynamic transport through the deformed rock mass is then modeled based on particle tracking simulations. By exploring various scenarios of different stress ratios and orientations, we systematically analyzed how the superimposed multiple geomechanical processes (i.e., compression-induced closure, shear-induced dilation, and stress-induced propagation) control the aperture patterns, flow fields, and transport behaviors of the fracture network. Our results show that an increased stress ratio tends to promote fracture shear dilation and thus enhance flow channelization, resulting in an anomalously early arrival of solute transport. Furthermore, the increased differential stress attempts to drive the growth of wing cracks that bridge pre-existing fractures and form new flow pathways. We observe a qualitative transformation of the flow structure from a disconnected to a connected regime accompanied by a significant alteration of its overall transport properties. This phenomenon is attributed to the superimposed effect of stress-driven crack propagation and shear-induced fracture dilation. By quantitative parameter analyses of global flow and transport properties, we further found that the breakthrough time median of particles is well correlated with the equivalent permeability of the fractured rock when the effect of new cracks is removed. However, this correlation is greatly reduced when fracture propagation is considered; instead, the breakthrough time shows a good correlation with mean tortuosity. Our findings have important implications for the strategy design of geothermal production and waste disposal in critically connected fractured geological media under various stress conditions.

文章链接地址: https://www.sciencedirect.com/science/article/pii/S136516092300206X?via%3Dihub