ASSIGNMENT
(DIANE, MUNSELL SOIL COLOR CHART &
MOHS HARDNESS SCALE)
DIANE
1.
Modelling of rock mass can be done by the following referred ways:
a.
CHILE
Continuous, Homogeneous, Isotropic and Linearly Elastic. This term is
most commonly assumed for the purposes of modelling of rock material. In the CHILE
case, we assume an ideal type of material which is not fractured, or if it is fractured
the fracturing can be incorporated in the elastic continuum properties.
(1)
Continuous
is mechanically continuous; there can be variations in the
mechanical property values but there are no mechanical
breaks
(2)
Homogeneous
has the same property values at all locations
(3)
Isotropic
has the same property values in different directions
(4)
Linearly Elastic
the stress-strain curve is a line with a constant slope,
all strains are instantaneous, and all energy can be
recovered
b.
DIANE
Discontinuous, Inhomogeneous, Anisotropic, and Not Elastic. In the
DIANE case, the nature of the real rock mass is recognized and we model
accordingly, still often making gross approximations. DIANE material is the rock mass
with which the engineer has to deal. The terms in these acronyms have the following
meanings.
(1)
Discontinuous
does contain mechanical breaks having effectively zero
Tensile strength
(2)
Inhomogeneous
has different property values at different locations
(3)
Anisotropic
has different property values in different directions
(4)
Non-Elastic
On unloading not all energy input can be recovered
and strains may be time dependent.
2.
Rock mechanics started with the CHILE approach and has now developed techniques to
enable the DIANE approach to be implemented. Both approaches have their advantages and
disadvantages, and the rock engineer will utilize each to maximal advantage according to the
circumstances. In the past, the rock mass was often modelled as a CHILE material. Nowadays,
there is recognition that the rock reality is DIANE and that numerical modelling should be able to
incorporate all the DIANE aspects as required by the rock engineering design problem in hand.
Often, the pragmatic approach to characterizing a rock mass is achieved by dividing the rock mass
into structural domains, each having different property values.
4.
In terms of the DIANE nature of real rock masses, almost all rock masses are fractured and
hence Discontinuous. The fractures are critical because mechanical failure usually occurs through
the presence of a major low-strength feature, such as reactivation of movement on a fracture, rock
blocks moving, or the influence of water in the fractures. We should always assume that the rock
mass is fractured .
5.
Similarly, it should be assumed that the rock mass is Inhomogeneous, unless there is some
evidence that the degree of inhomogeneity is not significant for the rock engineering design study
underway. The best method of characterizing and simplifying inhomogeneity is to divide the rock
mass into structural domains such that the property values can be assumed essentially constant
within a domain, and the best method for the choosing of structural domains is commonsense
geology supported by sampling and geo statistics.
6.
Anisotropy refers to having different property values in different directions
7.
The rock mass will always be 'Not Elastic' because there will always be some time-
dependent component to the induced strains, and loading/unloading curves will always exhibit
hysteresis. So, even though the elastic stress and strain distributions can often be helpful in
understanding the mechanics of a rock mass it should always be remembered that the rock mass
response to engineering perturbations is Not Elastic
MUNSELL COLOR CHART
1.
Albert Munsell, an artist and professor of art at the Massachusetts Normal Art School,
wanted to create a rational way to describe color through decimal notation instead of color names.
He first started work on the system in 1898 and published it in full form in A Color Notation in
1905. Other publications include Atlas of the Munsell Color System and A Grammar of Color.
Munsell system is still widely used as under
2.
a.
ANSI to define skin and hair colors for forensic pathology
b.
USGS for matching soil colors
c.
In prosthodontics during the selection of shades for dental restorations
d.
In breweries
Soil colors are most conveniently measured by comparison with a color chart. The collection
of charts generally used with soils is a modified version of the collection appearing in the Munsell
Book of CoIor and includes only that portion needed for soils, about one-fifth of the entire range
found in the complete edition.
3.
The nine charts in the Soil Collection display 322 different standard color chips
systematically arranged according to their Munsell notations, on cards carried in a loose Ieaf
notebook. The arrangement is by the three dimensions that combine to describe aII colors and are
known in the Munsell system as Hue, Value and Chroma .The Hue notation of a color indicates
its relation to Red, Yellow, Green, Blue, and Purple; the Value notation indicates its
lightness; and the Chroma notation indicates its strength (or departure from a neutral of the
same Iightness) . The colors displayed on
the individual Soil Color Charts are of constant
Hue, designated by a symbol in the upper right hand-corner of the card . Vertically, the colors
become successively lighter from the bottom of the card to the top in visually equal steps; their
value increases. Horizontally hey increase in Chroma from left to right. The Value notation of
each chip is indicated by the vertical scale in the far Ieft column of the chart. The Chroma notation
is indicated by the Horizontal scale across the bottom of the chart.
4.
The nomenclature of soil color consists of two complementary systems : (1) Color names;
and (2) The Munsell notation of color. Neither of these alone is adequate for all purposes .The
color names ae employed in all descriptions for publication and for general use. The Munsell
notation is used to supplement the color names wherever greater precision is needed , as a
convenient abbreviation in field descriptions , for expression of the specific relations between
colors, and for statistical treatment of color data. The Munsell notation is especially useful for
international correlation, since no translation of color names is needed . The names for soil
colors are common terms now so defined as to obtain uniformity and yet accord, as nearly as
possible, with past usage by soil scientists. The soil color names and their limits are given in
the diagrams which appear opposite each chart.
5.
“The MunselI notation for coIor consists of separate notations for hue, value, and Chroma,
which are combined in that order to form the color designation. The symbol for hue is the letter
abbreviation of the color of the rainbow (R for red, YR for Yellow-Red, Y for yellow) preceded by
numbers from 0 to 10. Within each letter range, the hue becomes more yellow and less red as the
numbers increase. The middIe of the letter range is at 5; the zero point coincides with the 10 point
of the next redder hue. Thus 5 YR is in the middIe of the yellow- red hue, which extends from 10R
(zero YR) to 10YR (zero Y) .”“The notation for value consists of numbers from 0, for absolute
black, to 10, for absolute white . Thus a color of value 5 / is visuaIIy midway between absoIute
white and absolute bIack . One of value 6/ is slightly less dark , 60 percent of the way from black
to white , and midway between vaIues of 5/ and 7/. “The notation for Chroma consists of numbers
beginning at 0 for neutral grays, and increasing at equal intervals to a maximum of about 20, which
is never really approached in soil . For absolute achromatic colors (pure grays, white, and black),
which have zero Chroma and no hue , the letter N(neutral) takes place of a hue designation.
6.
”In writing the Munsell notation, the order is hue, vaIue, chroma with a space between
the hue letter and the succeeding value number , and a diagonal between the two numbers for
value and chroma. If expression beyond the whole numbers is desired , decimals are always used
, never fractions. Thus the notation for a color of hue 5YR , value 5 , chroma 6 , is 5YR 5/6 ,
yellowish-red. The notation of color midway between the 5YR 5/6 and 5YR 6/6 chips is 5YR 5.5/6;
for one midway between 2.5 YR 5/6 and 5YR 6/8 , it is at 3.75 YR 5.5/7 . The notation is decimal
and capable of expressing any degree of refinement desired.
7.
In using the color charts, accurate comparison is obtained by holding the soil sample directly
behind the apertures separating the closest matching color chips . Rarely will the color of the
samples be perfectly matched by any color in the chart . The probability of having a perfect
matching of the sample color is less than one in hundred. It should be evident , however, which
color the sample lies between , and which is the closest match. The principle difficulties
encountered in using the soil color chart are
a.
In selecting the appropriate hue card
b.
In determining colors that are intermediate between the hues in the chart
c.
Distinguishing between value and Chroma where Chromas are strong
d.
Chart doesn’t include extreme dark, strong (low value, high Chroma) colors
encountered in moist soils
MOHS’S HARDNESS SCALE
1.
The Mohs’s scale was devised by the Austrian mineralogist Frederick Mohs in 1820 for
measuring hardness in minerals as a diagnostic property. It is based on the definition of hardness
as resistance to scratching and defined by the use of ten common minerals as standards, each of
which can scratch the mineral below it in hardness and can be scratched by the mineral above it.
The test is useful because most specimens of a given mineral are very close to the same hardness.
This makes hardness a reliable diagnostic property for most minerals.
2.
Mohs selected ten minerals of distinctly different hardness that ranged from a very soft
mineral (talc) to a very hard mineral (diamond). With the exception of diamond, the minerals are all
Mohs Hardness Scale
relatively common and easy or inexpensive to obtain.
Mineral
Hardness
the resistance of a material to being scratched. The test is conducted
Talc
1
by placing a sharp point of one specimen on an unmarked surface of
Gypsum
2
another specimen and attempting to produce a scratch. When
Calcite
3
conducting the test, the unknown specimen is placed on a table top
Fluorite
4
and firmly held in place with one hand. Then a point of the reference
Apatite
5
specimen is placed against a flat, unmarked surface of the unknown
Orthoclase
6
unknown, and deliberately dragged across the flat surface while
Quartz
7
pressing firmly. To avoid injury, the known specimen is dragged away
Topaz
8
from your body and parallel to the fingers that are holding the unknown
Corundum
9
specimen. The surface of the unknown specimen is examined. With a
Diamond
10
3.
MOHS HARDNESS TEST PROCEDURE
"Hardness"
is
specimen. The reference specimen is pressed firmly against the
finger any mineral fragments or powder that has been produced is
brushed away. Mineral powder or residue should not be confused with a scratch. A scratch will be
a distinct groove cut in the mineral surface, not a mark on the surface that wipes away. A hand lens
should be used to have a good observation . The test is conducted a second time to confirm results.
4.
HARDNESS COMPARISONS
Four situations might be observed when comparing the
hardness of two specimens:
a.
If Specimen A can scratch Specimen B, then Specimen A is harder than Specimen
B.
b.
If Specimen A does not scratch Specimen B, then Specimen B is harder than
Specimen A.
c.
If the two specimens are equal in hardness then they will be relatively ineffective at
scratching one another. Small scratches might be produced, or it might be difficult to
determine if a scratch was produced.
d.
If Specimen A can be scratched by Specimen B but it cannot be scratched by
Specimen C, then the hardness of Specimen A is between the hardness of Specimen
B and Specimen C.
5.
HARDNESS VARIATIONS IN A SINGLE MINERAL Many
minerals
have
variable
hardness. They have greater or lesser hardness depending upon the direction in which they are
being scratched. A well-known example of a mineral with variable hardness is kyanite which
frequently occurs in blade-shaped crystals. These crystals have a hardness of about 5 if they are
tested parallel to the long axis of the crystal, and a hardness of about 7 if they are tested parallel
to the short axis of a crystal. Another example is diamond. Parallel to the octahedral crystal faces,
a diamond crystal is almost impossible to saw and very difficult to polish. The diamond can be
broken in this direction by cleaving, and the best method for cutting it in this direction is with a laser.
The softest and best direction to saw or polish a diamond crystal is parallel to its cubic crystal faces.
6.
Weathering can also influence the hardness of a mineral specimen. Weathering changes a
mineral's composition, with the weathering product usually softer than the original material. When
testing the hardness or streak or other property of a mineral, the best way to test is on a freshly
broken surface with expected luster that has not been exposed to weathering.
7.
PRACTICAL APPLICATION OF HARDNESS TEST The Mohs Hardness Test is almost
exclusively used to determine the relative hardness of mineral specimens. This is done as part of
a mineral identification procedure in the field or in a laboratory when easily identified specimens
are being examined or where more sophisticated tests are not available. In industry, other hardness
tests are done to determine the suitability of a material for a specific industrial process or a specific
end-use application. Hardness testing is also done in manufacturing processes to confirm that
hardening treatments such as annealing, tempering, work hardening, or case hardening have been
done to specification.
8.
On the chart below minerals with a higher number can scratch all minerals with a lower
number. Italicized items are common items used to test hardness