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DarcyTools:A Computer Code for Hydrogeological Analysis of Nuclear Waste Repositories in fractured rock

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Journal of Applied Mathematics and Physics 2014年第6期2卷 365-383页

作者： Urban Svensson Michel Ferry Computer-aided Fluid Engineering AB Frankes vag 3371 65 LyckebySweden MFRDC 6 rue de la Perche44700 OrvaultFrance

A computer code for simulation of groundwater flow and transport is described. Both porous and fractured media are handled by the code. The main intended application is the analysis of a deep repository for nuclear waste and for this reason flow and transport in a sparsely fractured rock is in focus. The mathematical and numerical models are described in some detail. In short, one may say that the code is based on the traditional conservation and state laws, but also embodies a number of submodels (subgrid processes, permafrost, etc). An unstructured Cartesian grid and a finite volume approach are the key elements in the discretization of the basic equations. A multigrid solver is part of the code as well as a parallelization option based on the SPMD (Single-Program Multiple-Data) method. The main application areas are summarized and an application to a deep repository is discussed in some more detail.

关键词： fractured rock Inflow Prediction Deep Repository

Stress-dependent shear wave splitting and permeability in fractured porous rock

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Journal of rock Mechanics and Geotechnical Engineering 2019年第1期11卷 1-11页

作者： Daisuke Katsuki Marte Gutierrez Abdulhadi Almrabat Petroleum Engineering Department Colorado School of Mines Department of Civil and Environmental Engineering Colorado School of Mines

It is well known that shear wave propagates slower across than parallel to a fracture, and as a result, a travelling shear wave splits into two directions when it encounters a fracture. Shear wave splitting and permeability of porous rock core samples having single fracture were experimentally investigated using a high-pressure triaxial cell, which can measure seismic shear wave velocities in two directions mutually perpendicular to the sample axis in addition to the longitudinal compressive wave velocity. A single fracture was created in the samples using a modified Brazilian split test device, where the cylindrical sample edges were loaded on two diametrically opposite lines by sharp guillotines along the sample length. Based on tilt tests and fracture surface profilometry, the method of artificially induced tensile fracture in the sample was found to create repeatable fracture surfaces and morphologies. Seismic velocities of the fractured samples were determined under different levels of stress confinement and fracture shear displacement or mismatch. The effective confining stress was varied from 0.5 MPa to55 MPa, while the fractures were mismatched by 0 mm, 0.45 mm and 1 mm. The degree of matching of the fracture surfaces in the core samples was evaluated using the joint matching coefficient(JMC). Shear wave splitting, as measured by the difference in the magnitudes of shear wave velocities parallel(V_(S1))and perpendicular(V_(S2)) to the fracture, is found to be insensitive to the degree of mismatching of the fracture joint surfaces at 2 MPa, and decreased and approached zero as the effective stress was *** models for the stress-and JMC-dependent shear wave splitting and fractured rock permeability were developed based on the experimental observations. The effects of the joint wall compressive strength(JCS), JMC and stress on the stress dependency of joint aperture were discussed in terms of hydro-mechanical response. Finally, a useful relationship

关键词： fractured rock Sandstone Stress dependency Shear wave splitting Wave velocity Permeability Fracture stiffness Elastic modulus

Hyper-gravity experiment of solute transport in fractured rock and evaluation method for long-term barrier performance

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rock Mechanics Bulletin 2023年第3期2卷 1-14页

作者： Wenjie Xu Yingtao Hu Yunmin Chen Liangtong Zhan Ruiqi Chen Jinlong Li Duanyang Zhuang Qingdong Li Ke Li Center for Hyper-gravity Experimental and Interdisciplinary Research Zhejiang UniversityHangzhou310058China MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Zhejiang UniversityHangzhou310058China Department of Civil Engineering Hangzhou City UniversityHangzhou310015China Key Laboratory of Safe Construction and Intelligent Maintenance for Urban Shield Tunnels of Zhejiang Province Hangzhou310015China Advanced Materials Additive Manufacturing Innovation Research Center Hangzhou City University310015China

Hyper-gravity experiment enable the acceleration of the long-term transport of contaminants through fractured geological ***,the hyper-gravity effect of the solute transport in fractures are not well *** this study,the sealed control apparatus and the 3D printed fracture models were used to carry out 1 g and N g hyper-gravity *** results show that the breakthrough curves for the 1 g and N g experiments were almost the *** differences in the flow velocity and the fitted hydrodynamic dispersion coefficient were 0.97–3.12%and 9.09–20.4%,indicating that the internal fractures of the 3D printed fracture models remained stable under hyper-gravity,and the differences in the flow and solute transport characteristics were acceptable.A method for evaluating the long-term barrier performance of low-permeability fractured rocks was proposed based on the hyper-gravity *** solute transport processes in the 1 g prototype,1 g scaled model,and N g scaled model were simulated by the OpenGeoSys(OGS)*** results show that the N g scaled model can reproduce the flow and solute transport processes in the 1 g prototype without considering the micro-scale heterogeneity if the Reynolds number(Re)critical Reynolds number(Recr)and the Peclet number(Pe)the critical Peclet number(Pecr).This insight is valuable for carrying out hyper-gravity experiments to evaluate the long-term barrier performance of low-permeability fractured porous rock.

关键词： Hyper-gravity effect fractured rock 3D printed fracture Solute transport Long-term

Variation in hydraulic conductivity of fractured rocks at a dam foundation during operation

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Journal of rock Mechanics and Geotechnical Engineering 2021年第2期13卷 351-367页

作者： Yi-Feng Chen Jun Zeng Hongtao Shi Yifan Wang Ran Hu Zhibing Yang Chuang-Bing Zhou State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China Key Laboratory of rock Mechanics in Hydraulic Structural Engineering of the Ministry of Education Wuhan UniversityWuhan430072China China Three Gorges Projects Development Co. Ltd.Chengdu610000China

Characterizing the permeability variation in fractured rocks is important in various subsurface applications,but how the permeability evolves in the foundation rocks of high dams during operation remains poorly *** permeability change is commonly evidenced by a continuous decrease in the amount of discharge(especially for dams on sediment-laden rivers),and can be attributed to fracture clogging and/or hydromechanical *** this study,the permeability evolution of fractured rocks at a high arch dam foundation during operationwas evaluated by inverse modeling based on the field timeseries data of both pore pressure and discharge.A procedure combining orthogonal design,transient flow modeling,artificial neural network,and genetic algorithm was adopted to efficiently estimate the hydraulic conductivity values in each annual cycle after initial reservoir *** inverse results show that the permeability of the dam foundation rocks follows an exponential decay annually during operation(i.e.K/K0=0.97e^(-0.59t)+0.03),with good agreement between field observations and numerical *** significance of the obtained permeability decay function was manifested by an assessment of the long-term seepage control performance and groundwater flow behaviors at the dam *** proposed formula is also of merit for characterizing the permeability change in riverbed rocks induced by sediment transport and deposition.

关键词： Permeability variation fractured rock Fracture clogging Seepage control Dam engineering

Groundwater flow through fractured rocks and seepage control in geotechnical engineering: Theories and practices

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Journal of rock Mechanics and Geotechnical Engineering 2023年第1期15卷 1-36页

作者： Chuang-Bing Zhou Yi-Feng Chen Ran Hu Zhibing Yang State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China Key Laboratory of rock Mechanics in Hydraulic Structural Engineering of the Ministry of Education Wuhan430072China School of Infrastructure Engineering Nanchang UniversityNanchang330031China

Groundwater flow through fractured rocks has been recognized as an important issue in many geotechnical engineering *** key aspects of fundamental mechanisms,numerical modeling and engineering applications of flow in fractured rocks are ***,the microscopic mechanisms of fluid flow in fractured rocks,especially under the complex conditions of non-Darcian flow,multiphase flow,rock dissolution,and particle transport,have been revealed through a com-bined effort of visualized experiments and theoretical ***,laboratory and field methods of characterizing hydraulic properties(*** permeability,inertial permeability,and unsaturated flow parameters)of fractured rocks in different flow regimes have been ***,high-performance numerical simulation approaches for large-scale modeling of groundwater flow in frac-tured rocks and aquifers have been *** procedures for optimization design of seepage control systems in various settings have also been *** of coupled hydro-mechanical processes and control of flow-induced deformation have been ***,three case studies are presented to illustrate the applications of the improved theoretical understanding,characterization methods,modeling approaches,and seepage and deformation control strategies to geotechnical engi-neering projects.

关键词： fractured rock Groundwater flow Flow visualization Hydraulic property Hydromechanical coupling Groundwater flow modeling Seepage control

Friction factor correlation for airflow through broken rocks and its applications in mine ventilation

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International Journal of Mining Science and Technology 2020年第4期30卷 455-462页

作者： Leyla Amiri Seyed Ali Ghoreishi-Madiseh Ferri P.Hassani Agus P.Sasmito Department of Mining and Materials Engineering McGill UniversityMontrealQuebec H3A 2A7Canada Norman B.Keevil Institute of Mining Engineering University of British ColumbiaVancouverBritish Columbia V6T 1Z4Canada

The Atkinson equation along with its friction factor is commonly used to estimate pressure requirement in mine ***,friction factor correlation of flow through broken rock,typically found in blasted stope,gob,rock pit or block caving rock deposits,etc.,is currently ***,it is impractical to conduct direct measurements of flow resistance in an inaccessible broken rock *** paper aims to develop a new friction factor correlation of flow through broken rock that can be used directly in Atkinson *** proposed correlation is valid for broken rocks with diameter between 0.04 and 1.2 m and porosity ranging from 0.23 to 0.7.

关键词： Broken rock fractured rock Packed rock bed Large particle Pressure drop Friction factor

Frost-heaving pressure in geotechnical engineering materials during freezing process

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International Journal of Mining Science and Technology 2018年第2期28卷 287-296页

作者： Wang Pingsheng Zhou Guoqing State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and Technology Department of Civil Engineering Monash University

Energy and resources including coal, oil, and gas are in demand all over the world. Because these resources near the earth's surface have been exploited for many years, the extraction depth has *** mining shafts in the coal extraction process become deeper, especially in western China, an artificial freezing method is used and is concentrated in the fractured rock mass. The frost-heaving pressure(FHP)is directly related to the degree of damage of the fractured rock mass. This paper is focused on FHP during the freezing process, with emphasis on the frost-heaving phenomenon in engineering materials. A review of the frost phenomenon in the geotechnical engineering literature indicates that:(1) During the soil freezing process, the ice content that is influenced by unfrozen water and the freezing rate are the determining factors of FHP;(2) During the freezing process of rock and other porous media, the resulting cracks should be considered because the FHP may damage the crack structure;(3) The FHP in a joint rock mass is analyzed by the joint deformation in field and experimental tests and can be simulated by the equivalent expansion method including water migration and joint deformation.

关键词： Frost heaving pressure fractured rock Low temperature Freezing process Water and ice content

A Generalized Numerical Approach for Modeling Multiphase Flow and Transport in fractured Porous Media

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Communications in Computational Physics 2009年第6期6卷 85-108页

作者： Yu-Shu Wu Guan Qin Department of Petroleum Engineering Colorado School of MinesGoldenCO 80401USA Institute for Scientific Computation Texas A&M UniversityCollege StationTX 77843USA

A physically based numerical approach is presented for modeling multiphase flow and transport processes in fractured *** particular,a general framework model is discussed for dealing with fracture-matrix interactions,which is applicable to both continuum and discrete fracture *** numerical modeling approach is based on a general multiple-continuum concept,suitable for modeling any types of fractured reservoirs,including double-,triple-,and other multiplecontinuum conceptual *** addition,a new,physically correct numerical scheme is discussed to calculate multiphase flow between fractures and the matrix,using continuity of capillary pressure at the fracture-matrix *** proposed general modeling methodology is verified in special cases using analytical solutions and laboratory experimental data,and demonstrated for its application in modeling flow through fractured vuggy reservoirs.

关键词： Integrated finite difference conservation of mass and energy Newton iteration fully implicit reservoir simulation fractured rock

Numerical simulations of seepage flow in rough single rock fractures

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Petroleum 2015年第3期1卷 200-205页

作者： Qingang Zhang Yang Ju Wenbo Gong Liang Zhang Huafei Sun School of Mechanics and Civil Engineering China University of Mining and TechnologyBeijing 10083China State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China State Key Laboratory of Coal Resources and Safe Mining China University of Mining and TechnologyBeijing 100083China

To investigate the relationship between the structural characteristics and seepage flow behavior of rough single rock fractures,a set of single fracture physical models were produced using the WeierstrasseMandelbrot functions to test the seepage flow *** single fractures,with various surface roughnesses characterized by fractal dimensions,were built using COMSOL multiphysics *** fluid flow behavior through the rough fractures and the influences of the rough surfaces on the fluid flow behavior was then *** numerical simulation indicates that there is a linear relationship between the average flow velocity over the entire flow path and the fractal dimension of the rough *** is shown that there is good agreement between the numerical results and the experimental data in terms of the properties a of the fluid flowing through the rough single rock fractures.

关键词： Seepage flow Single fracture Rough surface Fractal dimension fractured rock