Presentation of soil in subject of engineering geology which have index properties of soil, engineering classification of soil, types of soil and more importantly definition of soil in engineering .

1. Soil

2. -is the mixture of minerals, organic matter, gases, liquids,
and myriad organisms that together support plant life.
Engineering definition:
civil engineering :
soil is the earth material that can be
disaggregated in water by gentle agitation.
Geologist: residual material formed in situ from
weathering of a parent material either bedrock or
sediment n
Soil scientist: organic rich material that supports plant
growth.
Soil

3. gravels soil organic soil

4. Engineering Properties of Soils
Mineral Soils

5. Soil profile

6. Horizons

7. Index properties of soil

8. Index properties
• Grain-size distribution
• Atterberg limits
• Density
• Specific gravity
• Consistency.

9. •Grain-size distribution. The grain-size distribution of soils is
determined by means of sieves and/or a hydrometer analysis,
and the results are expressed in the form of a cumulative semi-
log plot of percentage finer versus grain

10. •Atterberg limits. The Atterberg limits indicate the range of water content over
which a cohesive soil behaves plastically. The upper limit of this range is known
as the liquid limit (LL); the lower, as the plastic limit (PL). The LL is the water
content at which a soil will just begin to flow when slightly jarred in a prescribed
manner. The PL is the water content at which the soil will just begin to crumble
when rolled into threads 1/8 inch in diameter.
Shrinkage limit: Water content at which the soil changes from solid state to
semi-solid state.
Plastic limit: The moisture content at which the soil changes from semi solid
state to plastic state.
Liquid limit: At which a soil changes from plastic stage to liquid state.
•Density. The mass density of a soil material is its weight per unit volume. The dry
density of a soil is defined as the weight of solids contained in the unit volume of
the soil and is usually expressed in pounds per cubic foot.
•Specific gravity. The specific gravity of the solid constituents of a soil is the ratio
of the unit weight of the solid constituents to the unit weight of water. For routine
analyses, the specific gravity of sands and clayey soils may be taken as 2. 65 and
2. 70, respectively.
•Consistency. The consistency of an undisturbed cohesive soil may be expressed
quantitatively by the unconfined compressive strength qu.

11. Weight Volume relationships of soils

12. Engineering Classification
of Soils

13. I. Overview
A. Two Systems of Classification
1. Pedological Classifications
(soil weathering, texture, chemistry, profile thickness, etc.)
2. Engineering Classificationssoil texture degree of
plasticity (Atterberg Limits)

14. B. Overview of
Mechanics
As water content increases,
the shear strength decreases

15. C. Liquid Limit
•Soil is practically a liquid
•Shows minimal shear strength
•Defined as the moisture content
required
to close a distance of 0.5 inch
along
the bottom of a groove after 25
blows
of the liquid limit device

16. D. Plastic Limit
•Water content at which the soil is a plastic
•Less water content than liquid limit
•Wide range of shear strengths at plastic limit
•Defined as the moisture content % at which
the soil begins to crumble when rolled into 1/8”
diameter threads
E. Plasticity Index (PI)
•Difference between Liquid Limit and Plastic
Limit
• Important measure of plastic behavior
In General….
PI Degree of Plasticity 10-20 Medium plasticity
0 Nonplastic 20-40 High plasticity
1-5 Slightly plastic 40+ Very high plasticity
5-10 Low plasticity (from Burmister, 1949)

18. DEVELOPED IN 1929 AS THE PUBLIC ROAD ADMINISTRATION CLASSIFICATION
SYSTEM
MODIFIED BY THE HIGHWAY RESEARCH BOARD (1945)
Procedure for AASHTO Classification
(American Association of State
Highway and Transportation Officials)
DETERMINE THE PERCENTAGE OF SOIL PASSING THE #200 SIEVE
DETERMINE THE SUBGROUPS
FOR COARSE-GRAINED SOILS (GRAVEL AND SAND), DETERMINE THE PERCENT
PASSING THE #10, 40, AND 200 SIEVES, AND
DETERMINE THE LIQUID LIMIT AND PLASTICITY INDEX
THEN, DETERMINE SOIL GROUP OR SUBGROUP FROM TABLE 9.1
Procedure for AASHTO Classification

19. - For coarse-grained soils (gravel and sand), determine the
percent passing the #10, 40, and 200 sieves.
#10
#40
#200
3 “
#10
#40
#200
Cobble
Gravel
Very Coarse to Med Sand
Fine/Very Fine Sand
Silt/Clay

21. Procedure for AASHTO
Classification
Determine the percentage of soil passing the #200 sieve
Determine the subgroups
For fine-grained soils (silt & clay), determine the liquid
limit and plasticity index
Determine soil group or subgroup from Table 9.2

24. Determine the Group Index (usually reflects the relative strength of the material, where low values
have the greatest shear strength)
Determine the group index

25. Determine the group index

30. II. Unified System
Overview
A. Arthur Casagrande (USAF) proposed for the construction of Airfields
B. Basis
-Over half of material retained on #200
sieve, use textural characteristics
-Over half of material passes the #200 sieve, use plasticity-compressibility characteristics

31. Uniformity Coefficient
= D60/D10,
where we use the
% finer by weight
(% passing through)
for the values

40. 10% sand
46% silt
44% clay
Silt Clay
Example 1
42% sand
20% clay
38% silt
“Loam”

41. Sample 1
gravel sand silt clay
68% 28% 4% 0%
D60 = 3.5mm D10 = 0.23mm

42. Grain Size Analysis
(cont.)
• Sorting (Grading)
Parameters
• Uniformity
coefficient (Cu)
Cu = D60 / D10
= 3.5mm / .
23mm
= 1.5
• coefficient of
concavity (Cc)
Cc = [ D30 ]2
/ [ D10 x
D60 ]
= [ 1.8 ]2
/ [ 0.23 x
3.5 ]
= 4

43. http://www.soil-net.com/primary/ks2/topic6/topic6_factsheet.pdf
http://sosc.poly.edu/curriculum/urban-infrastructure/soil-
engineering/
http://www4.hcmut.edu.vn/~cnan/Principles%20of
%20geotechnical%20engineering%20%28Fifth%20Edition,
%20Das%29/83-99.PDF
https://www.google.com/search?
q=soil+profile&tbm=isch&tbo=u&source=univ&sa=X&ei=LQ
7iVPKaG8K1mAXhg4LQDQ&ved=0CB4QsAQ&biw=1366&bi
h=671#tbm=isch&q=soil+profile