文献类型：期刊文献

中文题名：考虑基质渗透性的岩体单裂隙渗流及影响因素的室内和数值试验研究

英文题名：Experimental and numerical investigations on fluid flow and corresponding influencing factors in a single rough-walled fracture surrounded by permeable matrix

作者：钟振[1,2,3];孟醒[1,2,3];胡云进[1,2,3];张丰收[4,5];李小双[1,2,3];周宇[1,2,3]

机构：[1]绍兴文理学院浙江省岩石力学与地质灾害重点实验室,浙江绍兴312000;[2]绍兴文理学院土木工程学院,浙江绍兴312000;[3]绍兴文理学院浙江省山体地质灾害防治协同创新中心,浙江绍兴312000;[4]同济大学土木工程学院,上海200092;[5]同济大学岩土与地下工程教育部重点实验室,上海200092

年份：2023

卷号：42

期号：9

起止页码：2148

中文期刊名：岩石力学与工程学报

外文期刊名：Chinese Journal of Rock Mechanics and Engineering

收录：CSTPCD、、EI(收录号：20233914792225)、Scopus、CSCD2023_2024、北大核心、CSCD、北大核心2020

基金：国家自然科学基金资助项目(51509154,41977256);浙江省自然科学基金资助项目(LGJ20E090001)。

语种：中文

中文关键词：岩石力学;裂隙岩体;裂隙粗糙度;基质渗透性;围压阈值;涡流

外文关键词：rock mechanics;fractured rocks;fracture roughness;matrix permeability;confining pressure threshold;vortex

中文摘要：为客观评价基质渗透性,并探明其在裂隙岩体渗流中的作用和比重,采用自主研制的应力–渗流耦合试验装置,开展水力耦合条件下完整岩芯和含贯穿单裂隙岩芯(泥岩、砂岩、石灰岩)的渗透试验研究,探究变围压(10~18 MPa)和变裂隙粗糙度系数(1.64~15.52)条件下裂隙、基质的渗流过程及规律。试验结果表明:基质和裂隙的渗透率均随围压的增加而降低,且裂隙渗透率的下降速率快于基质的下降速率,造成裂隙与基质的渗透率比值(K_(f)/K_(m))也逐渐下降;当围压增加至18 MPa时,泥岩的K_(f)/K_(m)已介于7~8(与裂隙粗糙度有关),小于一个数量级,基质渗透率已不容忽视。为进一步探索不可忽略基质渗透率的围压阈值,采用COMSOL构建含贯穿单裂隙岩芯的数值模型,模型中假定基质和裂隙内的渗流分别服从Darcy定律和Forchheimer定律,进而开展更大围压(3~53 MPa)范围和粗糙度系数(2.58~17.4)下的渗流数值模拟。数值模拟结果与试验结果较为一致,精准复现了裂隙及基质渗透率随围压和粗糙度系数的演化规律。若以K_(f)/K_(m)=10作为界定不可忽略基质渗透性的界限值,对应泥岩、砂岩、石灰岩的围压阈值分别为18,20,46 MPa。通过深入分析裂隙渗流场表明,随着围压和粗糙度系数的增加,裂隙的接触面积增大,过流面积相应降低,水流主要沿着缩窄的渗流通道贯穿裂隙;同时,过流通道的缩窄导致流速增加,在流场内形成涡流,进一步降低了裂隙的渗透性。系统探索了流体在裂隙和基质内的渗流过程及规律,提出采用K_(f)/K_(m)判定可否忽略基质渗透性的方法,为评价基质渗透性在裂隙岩体渗流中发挥的作用提供了定量指标。

外文摘要：To accurately assess matrix permeability and its role in the fluid flow through fractured rocks,flow-through experiments are conducted on both intact and split rock cores(including mudstone,sandstone and limestone)subjected to hydro-mechanically coupling conditions.By varying confining pressures(10–18 MPa)and fracture roughness(1.64 to 15.52),the influence of the confining pressure and the fracture roughness on the fluid flow within fracture and matrix were explored.The experimental results indicate that the permeability of both matrix and fracture shows a decreasing trend with increasing the confining pressure,and the permeability of fracture(Kf)declines faster than that of matrix(Km),resulting in a decrement in the ratio between them(K_(f)/K_(m)).Specifically,when the confining pressure increases to 18 MPa,K_(f)/K_(m) of mudstone reduces to 7–8(depend on fracture roughness),reflecting fracture permeability is in the same order with matrix permeability,and then matrix permeability should not be neglected.Furthermore,the numerical simulations were performed on fractured rocks with fracture roughness of 2.58–17.4,and under confining pressures of 3–53 MPa.The fluid flow in matrix and fracture were assumed to obey Darcy law and Forchheimer law,respectively.The numerical results match experimental ones well,and it successfully reproduces the evolutions of fracture and matrix permeability with confining pressure and fracture roughness.If we take K_(f)/K_(m) of 10 as a threshold,below which matrix permeability should be considered,then the critical confining pressure of 18,20,and 46 MPa can be determined for mudstone,sandstone and limestone,respectively.In addition,it is found that the contact area between rough-walled fracture surfaces increases with confining pressure and fracture roughness,leading to shrinkage in the flow channels,which consequently lowers the fracture permeability.Meanwhile,the velocity of flow within the narrowed channels will then accelerate,resulting in vortex inside the flow field,which further reduce the permeability of rough-walled fractures.This study systematically explores the fluid flow evolution within fracture and matrix,and provides a quantitative index K_(f)/K_(m) to evaluate the role of matrix permeability in fluid flow through fractured rocks.