裂隙扩张及惯性效应共同作用下裂隙中非达西渗流模拟研究  

Numerical investigation on the non-Darcy flow in fractures under the joint influence of fracture dilation and inertial effect

作　　者：戴君一 王礼春 孙晓林 DAI Junyi;WANG Lichun;SUN Xiaoin(Institute of Surface-Earth System Science,School of Earth System Science,Tianjin University,Tianjin300072,China;Critical Zone Observatory of Bohai Coastal Region,Tianjin University,Tianjin 300072,China;Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim,Tianjin 300072,China;Tianjin Geothermal Exploration and Development Design Institute,Tianjin 300250,China)

机构地区：[1]天津大学地球系统科学学院表层地球系统科学研究院,天津300072 [2]天津环渤海滨海地球关键带国家野外科学观测研究站,天津300072 [3]天津市环渤海地球关键带科学与可持续发展重点实验室,天津300072 [4]天津地热勘查开发设计院,天津300250

出　　处：《水文地质工程地质》2025年第2期44-52,共9页Hydrogeology & Engineering Geology

基　　金：国家自然科学基金面上项目(42477063)。

摘　　要：裂隙渗流是核废料、CO_(2)地质储存等重大工程的关键因素,常涉及高压环境。随着水力梯度增加,惯性效应增强,导致非达西效应(表观渗透率减少)。然而,前人研究常忽略高压下水力耦合作用对裂隙的扩张及相应的表观渗透率上升效应,造成刻画和模拟渗流过程不准确。为此,基于二维粗糙单裂隙和裂隙-基质系统,采用直接数值模拟方法研究裂隙扩张和惯性效应2种机制共同作用下的非达西渗流发展规律,探讨不同岩石基质力学性质对裂隙非达西渗流的影响。结果表明:(1)当压力梯度较小时,渗流处于达西流态,2种机制对渗流的影响都可以忽略,随着压力梯度逐渐升高,渗流进入非达西流态,2种机制都起到重要作用;(2)在2种机制竞争作用下,非达西渗流由惯性效应主导转向裂隙扩张主导,与之对应,裂隙等效水力开度呈现出先减小后增大的规律;(3)基质岩石的抗变形能力越弱,裂隙扩张主导效应越显著,并且使得由惯性效应转向裂隙扩张作用主导的临界值也越小,反之惯性效应主导显著。研究成果能为准确研判高压环境下裂隙介质中后达西渗流机制提供科学依据。The fluid flow in fractures is crucial for major engineering projects such as nuclear waste disposal and CO_(2) geological storage,which often involve with high-pressure environments.Previous studies have revealed that as hydraulic gradients increase,inertial effects become stronger,leading to non-Darcy effects(i.e.,reduced equivalent permeability).Unfortunately,past studies often neglected the influence of hydromechanical coupling on modifying fracture morphology.This oversight leads to a failure in capturing the effects of pressure-induced dilation and the consequent increase in equivalent permeability,resulting in inaccuracies in characterizing fluid flow in fractures.To this end,this study,based on two-dimensional rough single fractures and fracture-matrix systems,used direct numerical simulation methods to investigate the joint effects of two mechanisms:fracture dilation and inertial effects on the development of non-Darcy flow,and explored the influence of different mechanical properties of rock matrix on non-Darcy flow in fractures.The study leads to following key findings:(1)when the pressure gradient is small,the fluid flow is in Darcy flow regime,and the effects of both mechanisms on fluid flow can be ignored.As pressure gradient gradually increases,the non-Darcy flow regime emerges,where both mechanisms play important roles.(2)Under the joint effects of above two mechanisms,non-Darcy regime can be further divided into two phases:inertial effect domination and fracture dilation domination.Correspondingly,the equivalent hydraulic aperture decreases first and then increases.(3)Moreover,the weaker the deformation resistance of the matrix rock,the more significant the dominant effect of fracture dilation,and the smaller the critical value at which the transition from inertial effect to fracture dilation occurs.Conversely,inertial effects dominate significantly.The findings of this study can provide a scientific basis for accurately assessing fluid flow in fractured media in high-pressure environments,ultima

关 键 词：粗糙裂隙 非达西渗流 裂隙扩张作用 数值模拟 水力开度 临界雷诺数 

分 类 号：P641.2[天文地球—地质矿产勘探]