Environmetal Soil Properties and Behaviour

Environmetal Soil Properties and Behaviour


DisciplinaControle e Remediação da Poluição dos Solos5 materiais18 seguidores
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more about soil genesis 
and formation should consult specialized textbooks dealing with these subjects.
We classify soils because we want to have a quick appreciation (idea) of 
a soil under consideration. The purpose or role of the soil will tell us what 
kinds of soil property and soil behaviour information we require. We recog-
nize that many of the pieces of information require detailed and laborious 
laboratory tests. However, to sort out the various kinds of soils as candidates 
for the detailed tests, it is first necessary to choose appropriate candidates, 
and therein lies the dilemma: What kinds of simple tests and what kinds 
of information are needed? The discussion on soil classification has cho-
sen to consider the role of soil in the context of soil engineering as the basis 
for classification. It is understood that detailed laboratory tests as befits the 
requirements of specific projects/plans must be undertaken to provide for a 
complete classification scheme.
1.5.1 Soil Functionality
The concept of soil functionality proposed herein for use in soil engineering 
is in essence similar in spirit to the concept of soil quality used in agriculture. 
Soil quality has been defined by the Soil Science Society of America (SSSA) as 
the capacity of a specific kind of soil to function, within natural or managed 
23Origin and Function of Soils
ecosystem boundaries, to sustain plant and animal productivity, maintain 
or enhance water and air quality, and support human health and habitation 
(Karlen et al., 1997). To ensure that the definition of soil functionality covers 
the various soil functions, we define soil functionality (SF) as \u201cthe capacity of 
a specific soil to function under designed circumstances to meet its planned 
intentions or requirement without any loss of its original functional capa-
bility.\u201d The use of the concept of soil functionality as a measure of the soil 
and its functional capability essentially establishes a base that allows one to 
measure changes in specific soil function capability, that is, specific soil func-
tionality indices (SFI), to ensure that design or intended goals are met. This 
subject will be discussed in detail in Chapter 5.
To illustrate how one might use soil functionality and soil functionality 
indices in a soil engineering project, we use the example of the performance 
or role of a bottom engineered clay barrier (of a multibarrier system) of a 
nonhazardous waste landfill, as shown in Figure 1.9. The required properties 
of the clay barrier as placed in a multibarrier system is shown in the grey box 
located at the right of the figure. These are the properties required for the 
Filter membrane
Solid W
aste Landfill
Leachate collection &
leak detection system
Geomembrane
Natural base soil
Waste pile
Engineered clay
barrier
Waste
pile
Specified values for required design
performance of engineered clay barrier
\u2022 Maximum allowable permeability
 coefficient k 
\u2022 Maximum compressibility Cc
\u2022 Minimum shear strength and values of
 cohesion c and internal friction \u3c6
\u2022 Maximum swelling pressures
\u2022 Minimum density of compacted clay
\u2022 Partition coefficients koc and kd
\u2022 Diffusion coefficients for target
 contaminants
Functional capability of
engineered clay barrier
defined by
Soil functionality (SF) is defined by
how well functional capability is met
FIguRE 1.9
Typical landfill waste bottom engineered-barrier system for nonhazardous solid wastes. The 
functional capability of the clay used for the barrier is defined by the specified values of the 
various engineering properties required to fulfill design performance of the clay barrier. Soil 
functionality at any time after onset of service life is defined by how well functional capability 
of the clay barrier is met.
24 Environmental Soil Properties and Behaviour
clay barrier to fulfil its design function. Any degradation of any of the prop-
erties will detract from the functionality of the clay. In essence, for this par-
ticular example, one uses these specified values as indicators to determine soil 
functionality indices, which in this case will be clay functionality indices.
References
Atterberg, A.M., 1908, Studien auf dem Gebiet der Bodenkunde, Landw, Versuchsanstalt, 69.
Atterberg, A.M., 1911, Über die physikalishe Bodenuntersuchung und über die 
Plastiszität der Tone, Int. Mitt. für Bodenkunde, 1:10\u201343.
Casagrande, A., 1937, Classification and identification of soils, Proc. Amer. Soc. Civil 
Engrs., 73:783\u2013810.
Karlen, D.L., Mausbach, M.J., Doran, J.W., Cline, R.G., Harris, R.F., and Schuman, 
G.E., 1997, Soil quality: A concept, definition, and framework for evaluation, 
Soil Sci. Soc. Am. J., 61:4\u201310.
Keller, W.D., 1957, The Principles of Chemical Weathering, Lucas Brothers Publishers, 
Columbia, MO, 111 pp.
Waterways Experiment Station, 1953, Unified soil classification system, U.S. Corps of 
Engineers, Tech. Memo, 3-337, Vicksburg, MS.
25
2
Nature of Soils
2.1 Introduction
To understand and to evaluate or predict soil behaviour, one needs to have 
information on the properties of the soil under consideration. The properties 
of a particular soil are dependent on the nature of the soil, that is, its compo-
sition and how its various soil fractions interact with each other to provide 
the soil its intrinsic properties and attributes. Actions from environmental 
forces and human activities will impact the nature of a soil directly. These 
impacts will change the nature of a particular soil and can be anticipated 
with knowledge of the nature of the soil and the nature of the impacts. The 
various elements that combine to establish the nature of a soil and its proper-
ties are discussed in this chapter.
2.1.1 Soil Composition
We study soil composition because the nature of a soil is by and large deter-
mined by its composition. As we have seen from the discussion in Chapter 1, 
the composition of a soil is determined by the various pedogenic processes 
consistent with the particular region, climate, and anthropogenic activities. 
With the many different types of source materials, and the various factors 
and conditions governing weathering processes and regional controls, it 
follows that the composition of soils will vary from point to point and from 
location to location. To obtain a clearer picture of the nature of soils in 
general, it is expedient to consider them as complex systems consisting of 
solids, fluids, and gas. Common terminology refers to soils as three-phase 
systems consisting of a solid phase, a fluid phase, and a gaseous phase. In most 
cases, the gaseous phase is air, and the fluid phase is water with dissolved 
solutes. The solid phase consists of particles (soil solids) of various types 
such as carbonates, clay minerals, oxides, and so forth. The various types of 
soil solids are called soil fractions.
The various soil fractions, together with the fluid and gaseous phases in 
a soil, constitute the basic elements that define the composition of a soil. 
A key element in soil composition is the types of soil fractions. In large 
26 Environmental Soil Properties and Behaviour
measure, this will influence the proportioning of each of the phases in a 
soil. In a typical soil, one would have such soil fractions as clay miner-
als, the various oxides and hydrous oxides, humic material or soil organic 
matter, and carbonates and primary minerals. How the various soil solids, 
fluid, and gas phases interact with each other will determine the charac-
teristics and properties of the soil. In essence, soil composition is a funda-
mental feature of a soil that has considerable impact on the development of 
the structure (i.e., macrostructure) of the soil and the various physical and 
physicochemical properties of the soil. In turn, these properties will have