Designing with geosynthetics by Robert M. Koerner, April 14, , Prentice Hall edition, Hardcover in English - 5 edition. 1 Geosynthetic Institute, Folsom, PA (e-mail: but also for many new engineering applications and specific designs that were . Koerner (). Designing with Geosynthetics - 6th Edition Vol. 1. By Robert M. Koerner through four individual chapters on geosynthetics, geotextiles, geogrids and geonets.
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Library of Congress Cataloging-in-Publication Data Koerner, Robert M., Designing with geosynthetics / Robert M. Koernerth ed. musicmarkup.info Includes. Designing with. Geosynthetics. Second Edition. Robert M. Koerner, Ph. D., P. E.. Bowman Professor of Civil Engineering. Director. Geosynthetic Research. Read "Designing with Geosynthetics - 6Th Edition Vol. 1" by Robert M. Koerner available from Rakuten Kobo. Sign up today and get $5 off your first download.
Following the structure of previous editions, Volume 1 of this Sixth Edition proceeds through four individual chapters on geosynthetics, geotextiles, geogrids and geonets. Volume 2 continues with geomembranes, geosynthetic clay liners, geofoam and geocomposites. The two volumes must accompany one another. All are polymeric materials used for myriad applications in geotechnical, geoenvironmental, transportation, hydraulic and private development applications. In addition to describing and illustrating the various materials; the most important test methods and design examples are included as pertains to specific application areas. This latest edition differs from previous ones in that sustainability is addressed throughout, new material variations are presented, new applications are included and references are updated accordingly.
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Leonard Meirovitch. J Bai. Bimal Kumar. Manufacturing Processes for Advanced Composites. Flake C Campbell Jr. Design and Manufacture of Plastic Components for Multifunctionality. Vannessa Dr Goodship. Programmable Logic Controllers: Industrial Control. Khaled Kamel. Durability of Building Sealants.
Engineering Hydrology for Natural Resources Engineers. Ernest W. Andreas Athienitis. Ultra-Supercritical Coal Power Plants. Handbook of Nondestructive Evaluation, Second Edition. To produce tailor- made industrial fabrics,appropriate machinery is needed. Natural fibres: Natural fibers in the form of paper strips, jute nets, wood shavings or wool mulch are being used as geotextiles.
In certain soil reinforcement applications, geotextiles have to serve for more than years. But bio-degradable natural geotextiles are deliberately manufactured to have relatively short period of life. They are generally used for prevention of soil erosion until vegetation can become properly established on the ground surface. The fibres have silky luster and have white appear uneven in the unbleached condition. They constitute of pure cellulose and possess highest tenacity among allplant fibres.
Their quick biodegradability becomes weakness for their use as a geotextile. However, their life span can be extended even up to 20 years through different treatments and blendings. Thus, it is possible to manufacture designed biodegradable jute geotextile, having specific tenacity, porosity, permeability, transmissibility according to need and location specificity. Soil, soil composition, water, waterquality, water flow, landscape etc.
For erosion control and rural road considerations, soil protection from natural and seasonal degradation caused by rain, water, monsoon,wind and cold weather are very important parameters. Jute geotextiles, as separator, reinforcing and drainage activities, along with topsoil erosion inshoulder and cracking are used quite satisfactorily.
Further more, after degradation of jute geotextiles,lignomass is formed, which increases the soil organic content, fertility, texture and also enhance vegetative growth with further consolidation and stability of soil.
Synthetic Fibres: The four main synthetic polymers mostwidely used as the raw material for geotextiles are — polyester, polyamide, polyethylene and polypropylene.
Another group of polymers with a long production history is the polyamide family, the first of which was discovered in The next oldest of the four main polymer families relevant to geotextile manufactureis polyester, which was announced in The most recent polymer family relevant to geotextiles to bedeveloped was polypropylene, which was discovered in The second type is also an aliphatic polyamide obtained by thepolymerization of a salt of adipic acid and hexamethylene diamine.
These are manufactured in the form of threads which are cut into granules. Theyhave more strength but less moduli than polypropyleneand polyester They are also readily prone tohydrolysis. The fibre has high strength modulus, creep resistance and generalchemical inertness due too which it is more suitable for geotextiles.
It is attacked by polar solvent likebenzyl alcohol, phenol, and meta-cresol. At pH rangeof 7 to 10, its life span is about 50 years. It possesseshigh resistance to ultraviolet radiations.
However, theinstallation should be undertaken with care to avoid unnecessary exposure to light. Homo-polymers and copolymersare two types of polypropylene. Homopolymers are used for fibre and yarn application where as co-polymers are used for varied industrial applications.
Propylene is mainly available in granular form. Both polyethylene and polypropylene fibres are creep prone due to their low glass transition temperature. These polymers are purely hydrocarbons and arechemically inert. They swell by organic solvent and have excellent resistance to diesel and lubricating oils.
Soil burial studies have shown that except for lowmolecular weight component present, neither HDPEnor polyethylene is attacked by micro-organisms. The basic raw materials utilized forproduction of PVC is vinyl chloride. PVC is available in free- flowing powder form. They are usually made from polymers such as polyester or polypropylene.
The geotextiles are further prepared in three different categories — woven fabrics, non-woven fabrics and knitted fabrics Woven fabrics: Large numbers of geosynthetics are of woven type, which can be sub-divided into several categories based upon their method of manufacture. These were the first to be developed from the synthetic fibers.
As their name implies, they are manufactured by adopting techniques which are similar to weaving usual clothing textiles. This type has the characteristic appearance of two sets of parallel threads or yarns. The majority of low to medium strength woven geosynthetics are manufactured from polypropylene which can be in the form of extruded tape, silt film, monofilament or multifilament. Higher permeability is obtained with monofilament and multifilament than with flat construction only.
Woven Geotextile Fig 2. The fibers can be bonded together by adopting thermal, chemical or mechanical techniques or a combination of techniques.
The typeof fibre staple or continuous used has very little effect on the properties of the non — woven geosynthetics. Thermally bonded non-wovens contain wide range ofopening sizes and a typical thickness of about 0. Onthe other hand mechanically bonded non-wovenshave a typical thickness in the range of mm andalso tend to be comparatively heavy because a large quantity of polymer filament is required to provide sufficient number of entangled filament cross wires for adequate bonding.
In this process interlocking a series of loops of yarn together is made. An example of a knitted fabric is illustrated in figure. Only a very few knittedtypes are produced. All of the knitted geosyntheticsare formed by using the knitting technique in conjunction with some other method of geosynthetics manufacture, such as weaving. Knitted Geotextile Apart from these three main types of geotextiles, other geosynthetics used are geonets, geogrids, geo-cells, geomembranes, geo composites, etc.
Many of the reported properties are important in the manufacture and quality control of geosynthetics; however, many others are also important in design. The material properties related to the manufacture and quality control of geosynthetics are generally referred to as index properties and those related to the design as design or performance properties. Considering their different properties, the several geosynthetic products can perform different functions and, consequently, they should be designed to satisfy minimum criteria to adequately perform these functions.
The different functions performed by geosynthetics are discussed in Section The most common geosynthetic design methods are by experience, by specification, or by function Koerner, Design-by-specification is practiced, for example, by government agencies e.
It often consists in selecting geosynthetic products for common application areas, taking as a basis minimum or maximum-specified property values. Evaluate the criticality and severity of the application 2.
Determine the function s of the geosynthetic 3. Calculate, estimate, or otherwise determine the required property value for the function s 4. Test or otherwise obtain the allowable property of the candidate geosynthetic material 6.
Determine if the resulting factor of safety is significantly high for the site-specific situation under consideration 7. Prepare specifications and construction documents 8. Observe construction and post-construction performance. For example, a major cause of failure of roadways constructed over soft foundations is contamination of the aggregate base courses with the underlying soft subgrade soils Figure Contamination occurs due to: 1 penetration of the aggregate into the weak subgrade due to localized bearing capacity failure under stresses induced by wheel loads, and 2 inclusion of fine-grained soils into the aggregate because of pumping or subgrade weakening due to excess pore water pressures.
Subgrade contamination results in inadequate structural support, which often leads to premature failure of the system.
A geotextile can be placed between the aggregate and the subgrade to act as a separator and prevent the subgrade and aggregate base course from mixing Figure Among the different geosynthetics, geotextiles have been the products generally used in the function of separation. Examples of separation applications are the use of geotextiles between subgrade and stone base in roads and airfields, and between geomembranes and drainage layers in landfills.
Separation function of a geotextile placed between road aggregate and soft subgrade. Design and construction of stable slopes and retaining structures within space constraints are aspects of major economical significance in geotechnical engineering projects. For example, when geometry requirements dictate changes of elevation in a highway project, the engineer faces a variety of distinct alternatives for designing the required earth structures. Traditional solutions have been either a concrete retaining wall or a conventional, relatively flat, unreinforced slope Figure Although simple to design, concrete wall alternatives have generally led to elevated construction and material costs.
On the other hand, the construction of unreinforced embankments with flat slope angles dictated by stability considerations is an alternative often precluded in projects where design is controlled by space constraints. Geosynthetic products typically used as reinforcement elements are nonwoven geotextiles, woven geotextiles, geogrids, and geocells.
Reinforced soil vertical walls generally provide vertical grade separations at a lower cost than traditional concrete walls. Reinforced wall systems involve the use of shotcrete facing protection or of facing elements such as precast or cast-in-place concrete panels. Alternatively, steepened reinforced slopes may eliminate the use of facing elements, thus saving material costs and construction time in relation to vertical reinforced walls.
As indicated in Figure The effect of geosynthetic reinforcements on the stability of sand slopes is 12 illustrated in,which shows a reduced scale geotextile-reinforced slope model built using dry sand as backfill material.
As indicated in Table Both adequate hydraulic conductivity provided by a geotextile with a relatively open structure and adequate soil retention provided by a geotextile with a relatively tight structure should be offered by the selected product. In addition, considerations should be made regarding the long-term soil-to-geotextile flow compatibility such that the flow through the geotextile will notreduce excessively by clogging during the lifetime of the system.
The geosynthetic-to-soil system should then achieve an equilibrium that allows for adequate liquid flow with limited soil loss across the plane of the geotextile over a service lifetime compatible with the application under consideration. Filtration concepts are well established in the design of soil filters, and similar concepts can beused in the design of geotextile filters.
As the flow of liquid through the geotextile increases, the geotextile voids should be larger. However, large geotextile voids can lead to an unacceptable situation called soil piping, in which the soil particles are continuously carried through the geotextile, leaving large soil voids behind.
The liquid velocity then increases, which accelerates the process and may lead to the collapse of the soil structure.
This process can be prevented by selecting a geotextile with voids small enough to retain the soil on the upstream side of the fabric. It is the coarser soil fraction that must be initially retained. The coarser-sized particles eventually filter the finer-sized particles and build up a stable upstream soil structure Figure The test method used in the United States to determine the geotextile opening size is called the apparent opening size AOS test.
The drainage function of geosynthetics allows for adequate liquid flow with limited soil loss within the plane of the geotextile over a service lifetime compatible with the application under consideration. Thick, needle-punched nonwoven geotextiles have considerable void space in their structure and canconvey large amounts of liquid.
Geocomposite drains can transmit one to two orders of magnitude more liquid than geotextiles. Proper design should dictate what type of geosynthetic drainage material is necessary.
Except for the consideration of flow direction, the soil retention and the long-term compatibility considerations regarding the drainage function of geosynthetics are the same as those discussed in Section The geotextile, either when used as a drain itself or when placed onto a core to form geocomposite must fulfill the filtration function. The compatibility of the soil with the geotextile filter must be ensured over the lifetime of the system being built.
General references on design methods for the use of geosynthetics for drainage applications can be found in Holtz et al. As shown in Table Geosynthetic barriers are commonly used as liners for surface impoundments storing hazardous and nonhazardous liquids, as covers above the liquid surface of storage reservoirs, and as liners for canals used to convey water or chemicals.
Geosynthetic barriers are also used as secondary containment for underground storage tanks and in applications related to dams and tunnels. Of particular relevance for groundwater applications is the use of geosynthetic barriers for seepage control HDPE vertical barrier systems. A common application of geosynthetics as infiltration barriers is for base and cover liner systems of landfills.
In landfill applications, infiltration barriers are 14 typically used instead of or in addition to low-hydraulic conductivity soils.
Base liners are placed below the waste to prevent liquids from the landfill leachate from contaminating the underlying ground and the groundwater. Geosynthetic cover liner systems are placed above the final waste configuration to keep precipitation water from entering the waste and generate leachate. If a building or other structure is constructed on a landfill, a geosynthetic barrier may be placed under the building foundation to provide a barrier for vapors such as landfill gas.
The use of geosynthetics in infiltration barriers is further described in Koerner 6. A common example is the use of geotextiles to provide protection against puncture of geomembranes in waste and liquid containment systems. Adequate mechanical protection must be provided to resist both short-term equipment loads and long-term loads imparted by the waste. Experience has shown that geotextiles can play an important role in the successful installation and longerterm performance of geomembranes by acting as a cushion to prevent puncture damage of the geomembrane.
In the case of landfill base liners, geotextiles can be placed 1 below the geomembrane to resist puncture and wear due to abrasion caused by sharp-edged rocks in the subgrade, and 2 above the geomembrane to resist puncture caused either by the drainage aggregate or direct contact with waste materials. Likewise, in the case of landfill cover liners, geotextiles can be placed below the geomembrane to reduce risk of damage by sharp objects in the landfill and above the geomembrane to prevent damage during placement of drainage aggregate or cover soil.
Key characteristics for the geotextile cushions are polymer type, mass density, method of manufacture, and construction survivability.
Detailed procedures and methods for conducting these evaluations are described by Holtz et al. The fabrics are used to provide tensile strength in the earth mass in locations where shear stress would be generated.
Moreover, to allow rapid dewatering of the roadbed, the geotextiles need to preserve its permeability without losing its separating functions. Its filtration characteristics must not be significantly altered by the mechanical loading.
Railway Works: The development of the railway networks is being greatly boosted by the present state of economy because of their profitability in view of increasing cost of energy and their reliability as a result of the punctuality of trains even in the adverse weather conditions. The woven fabrics or non-wovens are used to separate the soil from the sub-soil without impeding the ground water circulation where ground is unstable.
Enveloping individual layers with fabric prevents the material wandering off sideways due to shocks and vibrations from running trains. When used in conjunction with natural or artificial enrockments, they act as a filter. For erosion prevention, geotextile used can be either woven or nonwoven. The woven fabrics are recommended in soils of larger particle size as they usually have larger pore size. Nonwovens are used where soils such as clay silt are formed.
Where hydrostatic uplift is expected, these fabrics must be of sufficiently high permeability. Such wash in soil causes clogging of the drains and potential surface instability of land adjacent to the drains. The use of geotextiles to filter the soil and a more or less single size granular material to transport water is increasingly seen as a technically and commercially viable alternative to the conventional systems. Geotextiles perform the filter mechanism for drainages in earth dams, in roads and highways, in reservoirs, behind retaining walls, deep drainage trenches and agriculture.
Caselon playing fields are synthetic grass surfaces constructed of light resistance polypropylene material with porous or nonporous carboxylated latex backing pile as high as 2. Astro Turf is a synthetic turf sport surface made of nylon 6,6 pile fibre knitted into a backing of polyester yarn which provides high strength and dimensional stability.
The nylon ribbon used for this is of 55 Tex. It is claimed that t surface 16 can be used for Modern Astro Turfcontains polypropylene as the base material. For the improvement of muddy paths and trails those used by cattleor light traffic, nonwoven fabrics are used and are folded by overlapping to include the pipe or a mass of grit. Utilization of geotextile in civil engineering is not a new technology.
But their modern uses have started with the advancement of synthetic and polymeric products and their ever increasing application in different forms and areas of civil engineering was initiated only a few decades ago.
Again uses of natural fibrous materials in the field of bioengineering, erosion control and agro-mulching are also recent practices.