Download or read book Assessing Alternative Conceptual Models of Fracture Flow written by and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Conceptual Models of Flow and Transport in the Fractured Vadose Zone written by National Research Council and published by National Academies Press. This book was released on 2001-05-21 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid flow and solute transport within the vadose zone, the unsaturated zone between the land surface and the water table, can be the cause of expanded plumes arising from localized contaminant sources. An understanding of vadose zone processes is, therefore, an essential prerequisite for cost-effective contaminant remediation efforts. In addition, because such features are potential avenues for rapid transport of chemicals from contamination sources to the water table, the presence of fractures and other channel-like openings in the vadose zone poses a particularly significant problem, Conceptual Models of Flow and Transport in the Fractured Vadose Zone is based on the work of a panel established under the auspices of the U.S. National Committee for Rock Mechanics. It emphasizes the importance of conceptual models and goes on to review the conceptual model development, testing, and refinement processes. The book examines fluid flow and transport mechanisms, noting the difficulty of modeling solute transport, and identifies geochemical and environmental tracer data as important components of the modeling process. Finally, the book recommends several areas for continued research.
Download or read book Alternative Conceptual Models and Codes for Unsaturated Flow in Fractured Tuff written by Clifford K. Ho and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Groundwater travel time (GWTT) calculations will play an important role in addressing site-suitability criteria for the potential high-level nuclear waste repository at Yucca Mountain, Nevada. In support of these calculations, Preliminary assessments of the candidate codes and models are presented in this report. A series of benchmark studies have been designed to address important aspects of modeling flow through fractured media representative of flow at Yucca Mountain. Three codes (DUAL, FEHMN, and TOUGH 2) are compared in these benchmark studies. DUAL is a single-phase, isothermal, two-dimensional flow simulator based on the dual mixed finite element method. FEHMN is a nonisothermal, multiphase, multidimensional simulator based primarily on the finite element method. TOUGH2 is anon isothermal, multiphase, multidimensional simulator based on the integral finite difference method. Alternative conceptual models of fracture flow consisting of the equivalent continuum model (ECM) and the dual permeability (DK) model are used in the different codes.
Download or read book Advanced Conceptual Models for Unsaturated and Two Phase Flow in Fractured Rock written by and published by . This book was released on 2003 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project was initiated in FY03. As of December 2003, we have accomplished the following: (1) We conducted a more detailed evaluation of the preliminary experiments used to develop our investigative approach. In those experiments, water was invaded at a variety of flow rates into an air-filled, two dimensional analog fracture network. Results demonstrated the critical control that fracture intersections place on two-phase flow in fracture networks. At low flows, capillary and gravitational forces combined to create a narrow pulsing flow structure that spanned the system vertically. At higher flows, viscous forces acted to remove the pulsation; however, the flow structure remained narrow. The intersections acted to impose a narrow ''slender ladder'' structure on the flowing phase that did not expand with depth, but instead remained focused. A manuscript documenting this effort has been published in Water Resources Research [Glass et al., 2003a]. (2) We initiated a collaborative relationship with a research group at Seoul National University. This group, which is led by Dr. Kang-Kun Lee is also using a combined experimental numerical approach to consider DNAPL migration in fracture networks. They are particularly interested in the influence of ambient groundwater flows, making their work complementary to ours. The first fruit of that collaboration is an article demonstrating that modification of an Invasion Percolation algorithm to include gravity and the first-order effects of viscous forces shows good agreement with physical experiments in a simplistic fracture network. Results were published in Geophysical Research Letters [Ji et al., 2003a]. (3) We carried out an extensive review of models for fracture networks. These include models developed from observations of networks on outcrops at several scales and stochastic models that are prevalent in the literature from the 1980s to very recent developments. The results of this review were included as par t of a review paper co-authored by Rajaram, which was submitted to Reviews in Geophysics [Molz et al., in press]. (4) We prepared a manuscript based on previous work that will be used to support the development of our new conceptual model(s) for transport in fractured rock. Eight experiments were conducted to evaluate the repeatability of flow under nearly identical conditions and to characterize general patterns in flow behavior. Collected data revealed that flow generally converged to a single fracture in the bottom row of blocks. Periods of pathway switching were observed to be more common than periods with steady, constant flow pathways. We noted the importance of fracture intersections for integrating uniform flow and discharging a ''fluid cascade'', where water advances rapidly to the next capillary barrier creating a stop and start advance of water through the network. The results of this simple experiment suggest that the interaction of multiple fracture intersections in a network creates flow behavior not generally recognized in popular conceptual and numerical models. A manuscript documenting this effort has been accepted for publication in Vadose Zone Journal [Wood et al., 2003]. (5) Slender transport pathways have been found in laboratory and field experiments within unsaturated fractured rock. We considered the simulation of such structures with a Modified form of Invasion Percolation (MIP). Results show that slender pathways form in fracture networks for a wide range of expected conditions, can be maintained when subsequent matrix imbibition is imposed, and may arise even in the context of primarily matrix flow due to the action of fractures as barriers to inter-matrix block transport. A manuscript documenting this effort has been submitted to Geophysical Research Letters [Glass et al., 2003b].
Download or read book Characterization Modeling Monitoring and Remediation of Fractured Rock written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2021-01-29 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fractured rock is the host or foundation for innumerable engineered structures related to energy, water, waste, and transportation. Characterizing, modeling, and monitoring fractured rock sites is critical to the functioning of those infrastructure, as well as to optimizing resource recovery and contaminant management. Characterization, Modeling, Monitoring, and Remediation of Fractured Rock examines the state of practice and state of art in the characterization of fractured rock and the chemical and biological processes related to subsurface contaminant fate and transport. This report examines new developments, knowledge, and approaches to engineering at fractured rock sites since the publication of the 1996 National Research Council report Rock Fractures and Fluid Flow: Contemporary Understanding and Fluid Flow. Fundamental understanding of the physical nature of fractured rock has changed little since 1996, but many new characterization tools have been developed, and there is now greater appreciation for the importance of chemical and biological processes that can occur in the fractured rock environment. The findings of Characterization, Modeling, Monitoring, and Remediation of Fractured Rock can be applied to all types of engineered infrastructure, but especially to engineered repositories for buried or stored waste and to fractured rock sites that have been contaminated as a result of past disposal or other practices. The recommendations of this report are intended to help the practitioner, researcher, and decision maker take a more interdisciplinary approach to engineering in the fractured rock environment. This report describes how existing tools-some only recently developed-can be used to increase the accuracy and reliability of engineering design and management given the interacting forces of nature. With an interdisciplinary approach, it is possible to conceptualize and model the fractured rock environment with acceptable levels of uncertainty and reliability, and to design systems that maximize remediation and long-term performance. Better scientific understanding could inform regulations, policies, and implementation guidelines related to infrastructure development and operations. The recommendations for research and applications to enhance practice of this book make it a valuable resource for students and practitioners in this field.
Download or read book Rock Fractures and Fluid Flow written by National Research Council and published by National Academies Press. This book was released on 1996-08-27 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific understanding of fluid flow in rock fracturesâ€"a process underlying contemporary earth science problems from the search for petroleum to the controversy over nuclear waste storageâ€"has grown significantly in the past 20 years. This volume presents a comprehensive report on the state of the field, with an interdisciplinary viewpoint, case studies of fracture sites, illustrations, conclusions, and research recommendations. The book addresses these questions: How can fractures that are significant hydraulic conductors be identified, located, and characterized? How do flow and transport occur in fracture systems? How can changes in fracture systems be predicted and controlled? Among other topics, the committee provides a geomechanical understanding of fracture formation, reviews methods for detecting subsurface fractures, and looks at the use of hydraulic and tracer tests to investigate fluid flow. The volume examines the state of conceptual and mathematical modeling, and it provides a useful framework for understanding the complexity of fracture changes that occur during fluid pumping and other engineering practices. With a practical and multidisciplinary outlook, this volume will be welcomed by geologists, petroleum geologists, geoengineers, geophysicists, hydrologists, researchers, educators and students in these fields, and public officials involved in geological projects.
Download or read book Use of Hydraulic Tests to Identify Conceptual Models of Heterogeneity for Fractured Rock Aquifers written by Pablo A. Cello and published by . This book was released on 2011-09-09 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: Important aquifers, petroleum reservoirs, geothermal reservoirs, and waste disposal sites throughout the world are located in fractured rock formations. Responsible management of these resources and sites requires appropriate field characterization studies and modeling techniques to assess the impact of management alternatives. Characterization and modeling of aquifers is particularly challenging in fractured media, where flow is concentrated into channels and thus violates the assumptions of traditional analysis approaches. The General Radial Flow (GRF) model is an alternative method for hydraulic test interpretation that infers an additional parameter, the flow dimension n, to describe the flow geometry. Previous studies have reported non-integer flow dimensions for a number of aquifers and reservoirs of various rock types, suggesting that flow is dominated by a series of fractal channels [Acuna and Yortsos, 1995]. Typically, the information carried by the flow dimension is ignored in subsequent modeling studies. The present work is a Monte Carlo analysis of numerical models of aquifer tests in two-dimensional fractured media, with the objective to identify stochastic models of aquifer heterogeneity that consistently produce stable apparent flow dimensions in agreement with those inferred from aquifer test conducted in fractured rock aquifers. The flow dimension is examined first for three conventional stochastic models of the transmissivity field: multivariate log Gaussian (mvG), Fractional Brownian Motion (fBm), and Site Percolation Network (SPN). Then, the more realistic discrete fracture network (DFN) model, with fracture lengths distributed as a power-law is analyzed. The study is focused on the relationships among the parameters of a DFN, the flow dimension, and the regime of diffusion of pressure transients of aquifer tests (e.g., Fickian or non-Fickian). Results demonstrate that the DFN model is the best candidate to represent the heterogeneity of fractured rock aquifers. In particular for the DFN model, the apparent flow dimension and anomalous diffusion exponent k depend on both the density and the power of the fracture length distribution, and thus also on the connectivity regime of the fracture network system. Depending on the connectivity regime, the apparent flow dimension stabilizes to less than the Euclidean dimension and the apparent value of k
Download or read book Rock Fractures and Fluid Flow written by National Research Council and published by National Academies Press. This book was released on 1996-09-27 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific understanding of fluid flow in rock fracturesâ€"a process underlying contemporary earth science problems from the search for petroleum to the controversy over nuclear waste storageâ€"has grown significantly in the past 20 years. This volume presents a comprehensive report on the state of the field, with an interdisciplinary viewpoint, case studies of fracture sites, illustrations, conclusions, and research recommendations. The book addresses these questions: How can fractures that are significant hydraulic conductors be identified, located, and characterized? How do flow and transport occur in fracture systems? How can changes in fracture systems be predicted and controlled? Among other topics, the committee provides a geomechanical understanding of fracture formation, reviews methods for detecting subsurface fractures, and looks at the use of hydraulic and tracer tests to investigate fluid flow. The volume examines the state of conceptual and mathematical modeling, and it provides a useful framework for understanding the complexity of fracture changes that occur during fluid pumping and other engineering practices. With a practical and multidisciplinary outlook, this volume will be welcomed by geologists, petroleum geologists, geoengineers, geophysicists, hydrologists, researchers, educators and students in these fields, and public officials involved in geological projects.
Download or read book Development and Experimental Evaluation of Models for Low Capillary Number Two phase Flows in Rough Walled Fractures Relevant to Natural Gradient Conditions written by Robert J. Glass and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Conceptual Models of Fluid Flow in Fractures written by Rajsekhar Kona and published by . This book was released on 1994 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radioactive Waste Management written by and published by . This book was released on 1981 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ASCE Combined Index written by American Society of Civil Engineers and published by . This book was released on 1996 with total page 1212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Indexes materials appearing in the Society's Journals, Transactions, Manuals and reports, Special publications, and Civil engineering.
Download or read book Environmental Assessment written by and published by . This book was released on 1986 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume 1. Chapters 1-5 - Volume 2. Chapters 6-Appendix B - Volume 3. Appendix C.
Download or read book Draft Environmental Impact Statement for a Geologic Repository for the Disposal of Spent Nuclear Fuel and High level Radioactive Waste at Yucca Mountain Nye County Nevada Impact analyses written by United States. Department of Energy. Office of Civilian Radioactive Waste Management and published by . This book was released on 1999 with total page 944 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Site Characterization Progress Report written by and published by . This book was released on 1994 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1990 with total page 972 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Site Assessment and Remediation Handbook written by Martin N. Sara and published by CRC Press. This book was released on 2003-06-27 with total page 1161 pages. Available in PDF, EPUB and Kindle. Book excerpt: Completely revised and updated, the Second Edition of Site Assessment and Remediation Handbook provides coverage of new procedures and technologies for an expanded range of site investigations. With over 700 figures, tables, and flow charts, the handbook is a comprehensive resource for engineers, geologists, and hydrologists conducting site investi
