Prefabricated Vertical Drains for Enhanced In Situ Remediation
Author: J. J. Bowders, M. A. Gabr, O. M. Collazos and J. D. Quaranta | Size: 630 KB | Format:PDF | Quality:Original preprint | Publisher: Geosynthetics Research and Development in Progress | pages: 13
Prefabricated vertical drains (PVDs), also known as wick or strip drains, commonly used to accelerate consolidation of fine-grained soils and sludges, have been successfully demonstrated for enhancing in situ remediation of contaminated soils and groundwater. Over the last decade, the technology basis was developed for using PVDs to accelerate in situ flushing, i.e., removal of contaminants below the groundwater table. During the last five years, the basis for using PVDs to enhance soil vapor extraction systems, i.e., removal of contaminated soil gas in the vadose zone was developed. Both of these geosynthetic applications have been field demonstrated on a limited basis. The first at an abandoned TCE evaporation pond at a U.S. Department of Energy processing plant and the second at a municipal solid waste landfill experiencing subsurface lateral migration of methane gas. The PVD enhanced remediation technologies have yet to find wide acceptance and utilization. Perhaps if several remaining issues are resolved and additional, well-instrumented field demonstrations are performed with results implemented in a design manual, consultants, remediation contractors and regulatory agencies will begin to include and utilize these technologies among their remediation options. In this paper we present an overview of the PVD-remediations technologies, a brief description of some past field demonstrations and our thoughts on research/development issues necessary to further the use of this technology.
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FILTRATION CRITERIA FOR PREFABRICATED VERTICAL DRAIN GEOTEXTILE FILTER JACKETS IN SOFT BANGKOK CLAY
Author: D.T. Bergado, R. Manivannan and A.S. Balasubramaniam | Size: 200 KB | Format:PDF | Quality:Original preprint | Publisher: GEOSYNTHETICS INTERNATIONAL | Year: 1996 | pages: 21
Filtration tests on soil-geotextile filter systems were conducted in the laboratory in order to evaluate the filtration and clogging performance of prefabricated vertical drain (PVD) geotextile filter jackets in soft Bangkok clay. Initially, the flow was very slow for all types of PVD geotextile filter jackets and the soil permeability characteristics controlled the flow behavior. Subsequently, flow increased with time followed by a loss of fine particles. Finally, flow decreased and reached an equilibrium stage. As a result of the laboratory filtration tests, filtration and clogging criteria are proposed for geotextile filter jackets on PVDs in soft Bangkok clay.
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Author: Albert T Yeung | Size: 580 KB | Format:PDF | Quality:Scanner | Publisher: Journal of Getotechnical and Geoenvironmental Engineering | Year: 1997 | pages: 5
Vertical drains and preloading are very effective and economical ground modification techniques for accelerating primary consolidation and compensating some secondary compression of soft compressible soils. If vertical sand drains are used, they can be installed at different diameters. The drain diameter required thus becomes a dependent variable in the design process and the drain spacing is determined a priori. The required parameters can be obtained after a few iterations. However, the number of iterations may increase significantly when prefabricated vertical drains or strip drains are used as the drain size is predetermined by manufacturers and available only in a very limited range. Design curves are developed for prefabricated vertical drains in this paper. The equivalent drain diameter is used as the independent variable and drain spacing becomes the dependent variable. Soil smear around the drain is considered but well resistance of the drain is neglected. The curves can be used to design a vertical drain system without unnecessary iterations and/or interpolations when the equivalent drain diameter, degree of consolidation required, time available, and pertinent geotechnical engineering properties of the soil to be consolidated are given.
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Author: Mark Randolph, Mark Cassidy, Susan Gourvenec & Carl Erbrich | Size: 4.2 MB | Format:PDF | Quality:Original preprint | Publisher: Int. Conf. on Soil Mechanics and Geotechnical Engineering (ICSMGE) | Year: 2005 | pages: 54
Design practice in offshore geotechnical engineering grew out of onshore practice, but the two areas have diverged over the last 30 years, driven partly by the scale of the foundation elements used offshore, and partly by fundamental differences in construction techniques.
Groups of many moderate sized piles used onshore are replaced by a few very large diameter piles for offshore applications. Similarly excavation of shallow soft sediments is replaced by the use of deep skirts, transferring the effective foundation depth to the level of the skirt tips, or by forcing footings to penetrate several diameters into the seabed; underwater installation has allowed the use of 'suction' (or underpressure) to aid installation of skirted foundations and caissons.
Emphasis in offshore design is focused more on capacity, paying particular attention to the effects of cyclic loading but generally with less concern on deformations compared with onshore design.
These differences have led to the development of separate design codes for offshore structures, which are in most cases more prescriptive than onshore codes but are also more sophisticated in key areas.
The state of the art report was prepared with colleagues Mark Cassidy and Susan Gourvenec from the University of Western Australia and Carl Erbrich from Advanced Geomechanics in Perth. It describes design principles for foundation and anchoring systems, ranging from shallow footings to piles and caissons, highlighting differences between onshore and offshore practice and also the link (or gap) between research and practice.
It outlines the challenges associated with offshore geotechnics, and reviews current design approaches and research trends for a range of foundation and anchor types.
Shallow foundation systems
In contrast to onshore design, offshore shallow foundations generally incorporate steel or concrete skirts that penetrate through surficial soft soils, forcing any failure surface down to skirt tip level.
Pumping, creating underpressure within the skirted compartments, is generally required to help penetrate the skirts. By subsequently sealing the compartments, the foundation is then able to withstand transient tensile loading, or high applied moments.
Wave loading during design storm conditions typically leads to larger horizontal and moment loading than for onshore structures and hence interaction between vertical, horizontal and moment loading is critical. Rather than the traditional approach of bearing factors accounting for inclination and eccentric of the applied load, three-dimensional failure envelopes in V-M-H space are used in offshore design.
Operation of mobile drilling rigs is still the area with the highest frequency of unpredicted foundation response, both during preloading of the spudcan foundations and during storm conditions.
As these rigs are used in increasing water depths, there is a need for innovative analysis techniques to assess spudcan installation; potential punch through into underlying weaker soil; performance during remobilising in areas where footprints from previous operations exist on the sea floor; and response during eccentric and combined V-M-H loading.
Site characterisation and anchoring systems in deep water Within each offshore region, there has been an inevitable progression from shallow to deep water, with recent installations in 2,000m of water in the Gulf of Mexico and deeper fields being planned.
This has necessitated considerable investment in research to validate new foundation and anchoring systems and also to improve methods for characterising the soil.
Facilities have evolved from fixed steel or concrete platforms, to floating facilities ranging from tension leg platforms with vertical tethers anchored to piles, to SPARs and tankers held in position by catenary mooring chains or, more recently, by lightweight 'taut wire' polyester ropes.
In the soft sediments typically found in deep water, novel 'full flow' penetrometers have been developed to obtain more reliable strength measurements. The average T-bar factor for different sites appears to have a smaller coefficient of variation than the average cone factor, reducing the need to calibrate an appropriate T-bar factor for each site from laboratory tests.
Floating facilities for deep water developments are restrained by mooring systems that may range from vertical tethers, in the case of a tension leg platform, to heavy chains in the form of catenaries that apply predominantly horizontal load to the anchors.
More recently, lightweight polyester ropes provide 'taut wire' mooring systems, where the resulting load on the anchor will lie at 35¦ to 45¦ from the horizontal.
For suction caissons, this angle is such that the failure mode will tend to be vertical, but the potential for a crack to form between the trailing edge of the caisson and the soil is an important consideration.
In ultra deep water, simplicity of installation is at a premium, and novel approaches such as the deep penetrating anchor (DPA) or the simple torpedo anchor become attractive.
Such anchors, typically 10m to 15m long, are allowed to free fall from more than 50m above the seabed and achieve terminal penetration velocities in the vicinity of 30m/s.
This allows the anchor to penetrate to two or three times the length of the anchor, achieving capacities of several MN per anchor. Although such anchors are relatively inefficient in terms of the ratio of holding capacity to weight, this is compensated for by their ease of installation.
ABOUT AUTHOR :
Professor Mark Randolph is director of the ARC-funded Special Research Centre for Offshore Foundation Systems at the University of Western Australia. His research includes many aspects of pile design, but is currently focused on offshore developments in deep water, especially soil characterisation and the estimation of limiting loads for foundation and anchoring systems.
Randolph interacts closely with the offshore industry, particularly through his role as a director of specialist geotechnical consultant, Advanced Geomechanics. He is a fellow of the Australian Academy of Science and of the UK Royal Academy of Engineering and was the 2003 Rankine Lecturer for the British Geotechnical Association. He has recently been awarded a five-year Federation Fellowship by the Australian Research Council.
ABSTRACT :
Design practice in offshore geotechnical engineering grew out of onshore practice, but the two application areas have tended to diverge over the last 30 years, driven partly by the scale of the foundation elements used offshore, and partly by fundamental differences in construction (or installation) techniques. Groups of many moderate-sized piles are replaced by a few very large diameter piles; excavation of shallow soft sediments is replaced by the use of deep skirts, transferring the effective foundation depth to the level of the skirt tips, or by forcing footings to penetrate several diameters into the seabed; underwater installation has allowed the use of ‘suction’ (or under-pressure) to aid installation of skirted foundations and caissons. Emphasis in design is focused more on capacity, paying particular attention to the effects of cyclic loading but generally with less concern on deformations compared with onshore design. These differences have led to the development of separate design codes for offshore structures, which are in most cases more prescriptive than onshore codes but are also more sophisticated in key areas. The paper describes design principles for foundation and anchoring systems ranging from shallow footings to piles and caissons, highlighting differences between onshore and offshore practice and also the link (or gap) between research and practice.
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RAM Elements V8i (SELECTseries 4) 13.0.0.22 1000 days trial
Size: 391 MB
This program provides unequaled flexibility for the design and analysis of different types of 2D or 3D structures containing linear members and shell elements.
The types of analysis available are: First order (Linear Analysis), Second order (P-Delta Analysis) and Dynamic (Seismic Analysis).
In addition, RAM Elements is also capable of designing hot-rolled or cold-formed steel members, wood (sawn lumber and glulam) and reinforced concrete members using the AISC 360-05 ASD, AISC 360-05 LRFD, AISC 360-10 ASD, AISC 360-10 LRFD, AISC 341-05, AISC 341-10, BS 5950-00, AISI 01 ASD, AISI 01 LRFD, AS 4100-98, CSA S16-09, NDS 05 ASD, NDS 05 LRFD, ACI 318-99, ACI 318-05 and BS8110-97 codes respectively. The program includes special modules for designing spread footings, combined footings, reinforced concrete columns, retaining walls, concrete walls, tilt-up walls, masonry walls, continuous beams and trusses.
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IMPORTANT NOTICE: You may use this software for evaluation purposes only.
If you like it, it is strongly suggested you buy it to support the developers.
By any means you may not use this software to make money or use it for commercial purpose.
The book reviews the two features of the variational approach: its use as a universal tool to describe physical phenomena and as a source for qualitative and quantitative methods of studying particular problems.
Berdichevsky’s work differs from other books on the subject in focusing mostly on the physical origin of variational principles as well as establishing their interrelations. For example, the Gibbs principles appear as a consequence of the Einstein formula for thermodynamic fluctuations rather than as the first principles of the theory of thermodynamic equilibrium. Mathematical issues are considered as long as they shed light on the physical outcomes and/or provide a useful technique for the direct study of variational problems. In addition, a thorough account of variational principles discovered in various branches of continuum mechanics is given.
In this book, the first volume, the author covers the variational principles for systems with a finite number of degrees of freedom; the variational principles of thermodynamics; the basics of continuum mechanics; the variational principles for classical models of continuum mechanics, such as elastic and plastic bodies, and ideal and viscous fluids; and direct methods of calculus of variations.
Variational Principles of Continuum Mechanics: II. Applications
This book, the second volume, describes how the variational approach can be applied to constructing models of continuum media, such as the theory of elastic plates; shells and beams; shallow water theory; heterogeneous mixtures; granular materials; and turbulence. It goes on to apply the variational approach to asymptotical analysis of problems with small parameters, such as the derivation of the theory of elastic plates, shells and beams from three-dimensional elasticity theory; and the basics of homogenization theory. A theory of stochastic variational problems is considered in detail too, along with applications to the homogenization of continua with random microstructures.
Both volume in a single 5.5MB rar file
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Author: Leonid P. Lebedev, Michael J. Cloud, Victor A Eremeyev | Size: 2.07 MB | Format:PDF | Quality:Original preprint | Publisher: World Scientific Publishing Company | Year: May 18, 2010 | pages: 373 | ISBN: 9814313122, ISBN-13: 978-9814313124
The tensorial nature of a quantity permits us to formulate transformation rules for its components under a change of basis. These rules are relatively simple and easily grasped by any engineering student familiar with matrix operators in linear algebra. More complex problems arise when one considers the tensor fields that describe continuum bodies. In this case general curvilinear coordinates become necessary. The principal basis of a curvilinear system is constructed as a set of vectors tangent to the coordinate lines. Another basis, called the dual basis, is also constructed in a special manner. The existence of these two bases is responsible for the mysterious covariant and contravariant terminology encountered in tensor discussions.
A tensor field is a tensor-valued function of position in space. The use of tensor fields allows us to present physical laws in a clear, compact form. A byproduct is a set of simple and clear rules for the representation of vector differential operators such as gradient, divergence, and Laplacian in curvilinear coordinate systems.
This book is a clear, concise, and self-contained treatment of tensors, tensor fields, and their applications. The book contains practically all the material on tensors needed for applications. It shows how this material is applied in mechanics, covering the foundations of the linear theories of elasticity and elastic shells.
The main results are all presented in the first four chapters. The remainder of the book shows how one can apply these results to differential geometry and the study of various types of objects in continuum mechanics such as elastic bodies, plates, and shells. Each chapter of this new edition is supplied with exercises and problems most with solutions, hints, or answers to help the reader progress. An extended appendix serves as a handbook-style summary of all important formulas contained in the book.
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Author: Frank M. White | Size: 35.3 MB | Format:PDF | Quality:Scanner | Publisher: McGraw-Hill | Year: January 5, 2005 | pages: 629 | ISBN: 0072402318, ISBN-13: 978-0072402315
Frank White's Viscous Fluid Flow, Third Edition continues to be the market leader in this course area. The text is for a senior graduate level elective in Mechanical Engineering, and has a strong professional and international appeal.
Author Frank White is has a strong reputation in the field, his book is accurate, conceptually strong, and contains excellent problem sets. Many of the problems are new to this third edition; a rarity among senior and graduate level textbooks. The references found in the text have been updated and reflect the most current information available. Users will also be interested to find explanations of, and references to ongoing controversies and trends in this course area.
Topically speaking, the text contains modern information on technological advances, such as Micro- and Nano-technology, Turbulence Modeling, Computational Fluid Dynamics (CFD), and Unsteady Boundary Layers.
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Author: Allan F. Bower | Size: 15.3 MB | Format:PDF | Quality:Original preprint | Publisher: CRC Press | Year: October 5, 2009 | pages: 820 | ISBN: 1439802475, ISBN-13: 978-1439802472
Modern computer simulations make stress analysis easy. As they continue to replace classical mathematical methods of analysis, these software programs require users to have a solid understanding of the fundamental principles on which they are based.
Applied Mechanics of Solids is a powerful tool for understanding how to take advantage of these revolutionary computer advances in the field of solid mechanics. Beginning with a description of the physical and mathematical laws that govern deformation in solids, the text presents modern constitutive equations, as well as analytical and computational methods of stress analysis and fracture mechanics. It also addresses the nonlinear theory of deformable rods, membranes, plates, and shells, and solutions to important boundary and initial value problems in solid mechanics.
The author uses the step-by-step manner of a blackboard lecture to explain problem solving methods, often providing the solution to a problem before its derivation is presented. This format will be useful for practicing engineers and scientists who need a quick review of some aspect of solid mechanics, as well as for instructors and students.
Borrowing from the classical literature on linear elasticity, plasticity, and structural mechanics, this book:
* Introduces concepts, analytical techniques, and numerical methods used to analyze deformation, stress, and failure in materials or components
* Discusses the use of finite element software for stress analysis
* Assesses simple analytical solutions to explain how to set up properly posed boundary and initial-value problems
* Provides an understanding of algorithms implemented in software code
Complemented by the author’s website, which features problem sets and sample code for self study, this book offers a crucial overview of problem solving for solid mechanics. It will help readers make optimal use of commercial finite element programs to achieve the most accurate prediction results possible.
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