Fondazioni – Lancellotta Calavera Mcgraw Hill. Uploaded by Valdri Vasquez. Download as PDF, TXT or read online from. Scribd. Flag for inappropriate content . Lancellotta PDF | DropPDF. – [Geotecnica] Fondazioni -. Lancellotta Calavera -. Mcgraw Hill by lucia_duca in Types > Books -. Non-fiction Thu. Renato Lancellotta. Kondner R.L. Lancellotta R. () Stability of a rigid column with non-linear restraint. Lancellotta R. and Calavera J. () Fondazioni.
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Home Documents Geotechnical Engineering 2nd ed. Post on Dec views. Renato Lancellotta gives a clear presentation of the fundamental principles of soilmechanics and demonstrates how these principles are applied in practice to engineer-ing problems and geotechnical design.
This is supported by numerous examples withworked solutions, clear summaries and extensive further reading lists throughout thebook. Thorough coverage is given to all classic soil mechanics topics such as boundaryvalue problems and serviceability of structures and to topics which are often missedout of other books or covered more briefly including: Geotechnical Engineering is suitable for soil mechanics modules on undergraduatecivil engineering courses and for use as a core text for specialist graduate geotechnicalengineering students.
It explores not only the basics but also several advanced aspectsof soil behaviour, and outlines principles which underpin more advanced professionalwork therefore providing a useful reference work for practising engineers.
Lancellotta, Calavera [Fondazioni – 1999]
Readers willgain a good grasp of applied mechanics, testing and experimentation, and methodsfor observing real structures. No part of this lancelpotta may be fnodazioni or reproduced or utilized in any form orby any electronic, mechanical, or other means, now known or hereafter invented,including photocopying and recording, or in any information storage or retrievalsystem, without permission in writing from the publishers.
The publisher makes no representation, express or implied, with regard to theaccuracy of the information contained in this book and cannot accept any legalresponsibility or liability for any efforts or omissions that may be made. First English language edition published by A. Includes bibliographical references and index. It hasbeen primarily designed as a classroom teaching book, but it also coversmore advancedaspects, usually included in upper level courses on civil and geotechnical engineering.
To provide a clear separation of basic and more advanced arguments, the material falavera in a series of focused sections, and having included much more material hasthe advantage of giving the teacher the possibility to adapt the book to his personalview, when it is being used in a one or two-semester course. Fkndazioni is no necessity for a motivation to study soil mechanics. Since lancellott beginningof time man has been a builder, he had to deal with earth pressures, groundwater flow,stability of earth constructions, settlement and stability of structures interacting withsoils.
Man learned to solve complex problems by caoavera and error, and, paradoxically,when he was successful, this ability remained invisible. The behaviour of soil is today approached on sound and rational bases, using con-cepts of continuummechanics, findazioni experimental evidences prove that fondazionni is a significantand powerful procedure.
To give this book a self-contained character, all basic concepts of continuummechanics and mathematical prerequisites have been collected in Chapters 2 and 3,but readers who have a good grasp of these prerequisites can obviously omit thesechapters and move from Chapter 1 to Chapter 4. Soils are natural materials and the solution of engineering problems requires theknowledge of the properties of real soils. These properties have to be investigated,rather then being prescribed, so that it is necessary to be familiarwith testing techniquesand to be aware of the relevance of field investigation.
However, both phases of programming and interpreting experimental tests requirea conceptual framework, and for this reason reference has been made throughout thisbook to the Critical State Theory.
The central idea of this theory is that volume changesplay a role so important as the effective stresses and it is the relation between the initialstate and the critical state that has a major influence on soil behaviour.
Moreover, thistheory also provides a link between fondazioji mechanics and previously grasped concepts aselasticity and plasticity, that in turn are extensively used in two final chapters, aimedat applications.
The material contained in this book has been organized and developed followingthis line of thought, and, having the students in mind, many worked examples havebeen disseminated throughout the book in order to show how basic principles areapplied to solve problems of engineering interest. Finally, the author thanksauthors and publishers and especially the Council of the Institution of Civil Engineersof London for permission to reproduce many figures from Gotechnique.
Renato Lanceloltta, November Chapter 1Origin, description andclassification of soilsThe beginning reader will quickly realize that calaverw are unusual engineering materials,mainly if compared with materials described in structural mechanics. The reason isthat soils lanceklotta natural materials, formed by the weathering of rocks, and the behaviourof soils is a legacy of natural processes, from their origin to the actual state. Thisgives soils a character of inhomogeneity and anisotropy, and basic parameters, suchas strength, stiffness and hydraulic conductivity, need to be measured instead of beingspecified and may vary over a wide range.
The discrete particles lzncellotta make up soils are not cslavera bounded together, they arefree to move relatively among themselves and, when a soil element deforms, the overalldeformation is essentially the result of relative sliding between particles and rotationof particles. Therefore, it is not surprising that soil behaviour is highly non-linear andirreversible. Furthermore, it must be realized that the voids or pores between particles are filledwith water, or there may be more than one fluid, typically water and air at near-surface depths, but there could be water and liquid and gaseous hydrocarbon in certaincircumstances.
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It follows that soils are multi-phase materials, their behaviour beinginfluenced by the interaction between solids and fluids. From this concise description, and mainly from the consideration that we have todeal with natural materials, it appears that a first step to learn about the behaviour ofsoils is certainly that of having a knowledge about the origin of soils.
For this reason,in this chapter we will study the weathering processes of rocks, as well as the mainfeatures of natural soil deposits. Then, we say that basic parameters, such as strength,stiffness and hydraulic conductivity, need to be measured by specific tests rather thenbeing specified. However, an accurate description of soils can help the engineer byproviding him with a general guidance about the expected soil behaviour.
Therefore,a second step is to learn how to describe fondazoini, by using a common language, in order tobenefit from any description. Finally, we need to learn how to classify soils, presumingthat soil samples within the same class have a similar behaviour. This history includes calavvera, transportation, deposition andpost-depositional changes.
The actual state of homogeneity and anisotropy of any soildeposit is calavdra to this formational history and to subsequent changes, summarizedin Figure 1. RocksWeatheringBiological weathering 1 2 3 4 Physicalprocesses: Origin, description and classification of soils Physical processes include the breakdown of rocks into particles.
This process of dis-integration is promoted by the presence of discontinuities cracks, joints and faults ,deriving from tectonic events as well as from stress relief due to uplift, erosion orchanges of fluid pressure.
When water enters rocks lancelllotta cracks and fissures, the iceformed by freezing exerts high pressures and is able to disintegrate lancellotat outer layer ofrocks. In addition, expecially in hot climates, the rock surface is subjected to a widerange of temperatures up to 60 Cgiving rise to cycles of expansion fondazionni contrac-tion.
The result is that outer layers can be calvera away and this process is calledexfoliation. Chemical weathering, or decomposition, is the breakdown of minerals into newcompounds, by the action of chemical agents such as acids in the rain and flowingwater and in the air. Weathering can also be attributed to plants and animals. Understanding chemical weathering requires to digress on some basic aspects of soilmineralogy, so thatwe start by recalling thatminerals are defined as naturally occurringinorganic substances, which have a definite chemical composition fondaizoni a regular atomicstructure to which its crystalline form is related.
Mineral composing rocks are mainly a combination of elements listed, in decreas-ing order of abundance, in Table 1.
The remaining minerals, with the exception of carbonates, do not appear in suchquantities to affect both physical and mechanical properties of common rocks andsoils. The fundamental unit of silicate minerals is the tetrahedron SiO4, formed by4 oxygen ions grouped around a single tetravalent silicon ion Figure 1. The bond-ing energy Si-O is half the bonding energy of the oxygen ion, so that this latter can belinked to another available silicon ion, or the excess of four negative valencies can bebalanced when the SiO4 group is linked to metal ions Mg, Fe, Ca.
This originates arrangements, or structures, of tetrahedra, and silicate minerals arethen grouped according to these arrangements. As an example, when the tedrahedra are linked by sharing three of four oxygen ions,and their bases lie in a common plane, the sheet structure of phyllosilicates is formed.
Sheet structures are found in micas and flaky minerals such as chlorite, talc and clayminerals. If the tetrahedron is sharing all its oxygen with adjacent tetrahedra, this origi-nates a three-dimensional structure, called three-dimensional framework.
The mineralquartz SiO2 is a representative of framework structure. Another example of framework is provided by feldspars, the most abundant groupin igneous rocks. Important non-silicate minerals are calcite CaCO3 and dolomite CaMg CO3 2 ,essential components of detrital calcareous sediments limestone, dolomite anddolomitic limestone. The processes most commonly involved in chemical weathering are represented bythe reactions of minerals with water, oxygen and organic acids.
Quartz an essential constituent of granites, of most sands and sandstones, alsofound abundantly in gneisses, quartzites, in some schists and other metamorphicrocks and muscovite which occurs in granites and other acid rocks as well as insedimentary rocks as micaceous sandstones are very stable minerals.
Geotechnical Engineering 2nd ed – [PDF Document]
On the con-trary, feldspar minerals are sensitive to weathering and their alteration forms clayminerals. Examples are provided by orthoclase potassium feldsparwhich alters throughhydrolysis, i. Other examples of chemical weathering processes consist of hydration absorp-tion of water molecules into the mineral structuresolution dissociation of mineralsinto ionsoxidation the combination of oxygen with a mineral to form oxidesand hydroxidesleaching the migration of ions produced by all the previouslyOrigin, description and classification of soils 5mentioned processescation exchange absorption of positively charged cations insolution onto the negatively charged surface of clays.
The rate of chemical weathering depends upon the presence of water and is greaterin wet climates than in dry climates. It is also correlated to the activity of vegetation,to the production of carbon dioxide and to the frequency of rain.
When the products of rock weathering disintegration and alteration are not trans-ported as sediments but accumulate in place, a residual soil originates. As can beinferred from their geographical distribution, residual soils are predominant in warm,humid regions, where they can develop significant thicknesses, up to about 30 m. If the current turbulence is greater thanthe settling velocity, the smaller sediments are transported in suspension.
The largestparticles are moved by dragging along the bottom, while intermediate particles lancelllotta by saltation. Finally, soluble materials can be transported in solution and mayprecipitate successively. Therefore transportation has the effect of sorting the particles in general the particles are coarser towards the place of origin and of abrasion, thusmodifying the shape of particles.
Theproperties of the aggregate are linked to the environment of deposition, which repre-sents the condition of accumulation and consolidation. For this reason it is importantto distinguish between continental glacial, alluvial, aeolian, paludal or lacustrine ,mixed estuarine, deltaic and marine environments.
Main features of these depositswill be discussed in Section 1. In this respect, the termclay lancellorta used to indicate particles smaller than 2m. But the same term is also usedmore generally to describe natural soils in which the properties of the clay size rangepredominate. Finally the term clay can be used to refer to specific minerals, as is the lancellofta the sequel. Clay minerals are hydrous aluminium silicates plus other metallic ions, and canform as either primary or secondary minerals.
They can only be seen with an electronmicroscope, since they are very small crystals, of platy-like ca,avera and of colloidalsize. On the basis of X-ray diffraction, it has been found that they are formed oftwo-dimensional sheets, which are kancellotta one upon another. These sheets are of two6 Origin, description and classification of soilskinds: There are dozens of clay minerals, depending on the way the basic sheets are stackedtogether and depending on the cations calavefa in the tetrahedral and octahedral sheets.
However, since the objective here is to show the cwlavera features of their microstruc-ture in order to elucidate qualitatively its influence on soil behaviour, it is sufficient todescribe only a few examples of clay minerals. Kaolinite caalvera made up of layers of one tetrahedral sheet and one octahedral sheet forthis reason kaolinite is also called a 1: Thebasic layer has a thickness of 0.
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A kaolinitecrystal typically contains 70 to layers. Origin, description and classification of soils 7Montmorillonite presents a more complicated structure Figure 1. The bonding between the silica sheets isrepresented by van der Waals forces, so it is a weak bond. Molecular water may also occur fodnazioni.
As a consequence, the crystals can be rather small the thickness can be of theorder of 1 nm and clay soils containing montmorillonite are susceptible to swelling,with important engineering implications. From the above description of microstructural features we can deduce that the seatof positive charges and the seat of negative charges do not calabera, so that a clayparticle exhibits a surface negatively charged.
It can then be expected that the interaction of adjacent soil particles, as well as theinteraction of a particle with its surrounding ambient, will be influenced by this netcharge deficiency and by this charge distribution.
Since the magnitude of the electrical charge calaverx directly related to the surface of theparticles, a measure of the surface area per unit mass of the particle is an indicatorof the influence of surface forces relative to mass forces on the behaviour of a soilparticle. This measure is termed specific surface. To neutralize the net charge deficiency, soil fonrazioni attract cations to its surface,as well as dipolar molecules of water.