ADDIS ABABA INSTITUTE OF TECHNOLOGYSCHOOL OF CIVIL AND ENVIRONMENTAL ENGINEERING

CENG 2141Soil Mechanics I

CENG 2141Soil Mechanics I

Instructor: Petros Fekadu11/2014

CHAPTER-2

SOIL PROPERTIESSOIL PROPERTIES

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Physical Parameters

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Physical Parameters ... Contd

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Physical Parameters ... Contd

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Physical Parameters ... Contd

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Physical Parameters ... Contd

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Physical Parameters ... Contd

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Physical Parameters ... Contd

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Physical Parameters ... Contd

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Physical Parameters ... Contd

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Gs: the ratio of the weight of a given volume of a material tothe weight of an equal volume of water.

Physical Parameters ... ContdPercent air voids (na) is theratio of the volume of air voidsto the total volume of the soilmass:

Air content (ac) is the ratio ofthe volume of air voids to thevolume of voids:

Specific volume (V) is thevolume of soil per unit volumeof solids:

Vv

n aa

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Percent air voids (na) is theratio of the volume of air voidsto the total volume of the soilmass:

Air content (ac) is the ratio ofthe volume of air voids to thevolume of voids:

Specific volume (V) is thevolume of soil per unit volumeof solids:

v

ac V

va

sVV

'V

Physical Parameters ... Contd

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Physical Parameters ... Contd

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Physical Parameters ... Contd

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Example 2.1Prove the following expression:

w1d

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Example 2.2A 1 m3 soil specimen weighs 18 kN and has amoisture content of 10%. The specific gravity of thesoil solids is 2.7. Calculate (a) , (b) d, (c) e,(d) n, (e) Vw, (f) S & (g) ac.

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Physical Parameters ... ContdRelative Density: a measure of the compactness of the soil

grains:

The compressibility and strength of a granular soil arerelated to its relative density. Denser soils being strongerthan looser soils.

N.B: The r/n b/n dry density and void ratio.

,then &

Relative Density: a measure of the compactness of the soilgrains:

The compressibility and strength of a granular soil arerelated to its relative density. Denser soils being strongerthan looser soils.

N.B: The r/n b/n dry density and void ratio.

,then &

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Example 2.3Calculate the relative density and classify thecompactness of a dry sandy soil with a weight of 50N, a total volume of 3000 cm3 and a specific gravityof 2.7. The void ratios of the material in its densestand loosest conditions are 0.75 and 0.25respectively.

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Calculate the relative density and classify thecompactness of a dry sandy soil with a weight of 50N, a total volume of 3000 cm3 and a specific gravityof 2.7. The void ratios of the material in its densestand loosest conditions are 0.75 and 0.25respectively.

Example 2.4In a certain borrow area A, the soil has e = 0.75, w = 20%and Gs = 2.7. The fill will have a total volume of 1000 m3, = 20 kN/m3 and w = 25%.(a) Calculate the volume of the soil to be excavated.(b) Determine the number of 10 m3 truck loads required toconstruct the fill.(c) If there is a soil in another borrow area B with e = 0.9and Gs = 2.7, which one do you prefer from economicalpoint of view? Cost of moving per m3 of soils A and B are150 Birr and 140 Birr respectively.(d) Estimate the amount of water to be added.

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In a certain borrow area A, the soil has e = 0.75, w = 20%and Gs = 2.7. The fill will have a total volume of 1000 m3, = 20 kN/m3 and w = 25%.(a) Calculate the volume of the soil to be excavated.(b) Determine the number of 10 m3 truck loads required toconstruct the fill.(c) If there is a soil in another borrow area B with e = 0.9and Gs = 2.7, which one do you prefer from economicalpoint of view? Cost of moving per m3 of soils A and B are150 Birr and 140 Birr respectively.(d) Estimate the amount of water to be added.