HOMEWORK SOLUTION

HW #3

GEOTECHNICAL ENGINEERING I

(Question no. 3.22-d,f, 3.24-b,e, 3.25-b,e……Al-Khafaji textbook)

3.22d % passing #4 = 80 % retained #4 = 100-80 = 20

% passing #200 = 20 % retained (#4-#200) = 80-20 = 60

LL = 40

PL = 32

PI = 40-42=8

< 50% passing #200 coarse grained

< 50% retained #4 sand

> 12% passing #200 use plasticity chart by plotting

LL = 40 and PI= 8 ML

Then the soil is SM

≥ 15% gravel Silty Sand with Gravel ……. Ans.

3.22d % passing #4 = 87 % retained #4 = 100-87 = 13

% passing #200 = 40 % retained (#4-#200) = 87-40 = 47

LL = 62

PL = 25

PI = 62-25=37

< 50% passing #200 coarse grained

< 50% retained #4 sand

> 12% passing #200 use plasticity chart by plotting

LL = 62 and PI= 37 CH

Then the soil is SC

≥ 15% gravel Clayey Sand ……. Ans.

3.22d % passing #4 = 74 % retained #4 = 100-74 = 26

% passing #200 = 12 % retained (#4-#200) = 74-12 = 62

LL = 19

PL = 12

PI = 19-12=7

D60 = 2.34

D30 = 0.48 interpolation

D10 = 0.034

< 50% passing #200 coarse grained

< 50% retained #4 sand

5-12% passing #200 has double symbol

Since Cu > 6 and Cc 1≤Cc≤3 and using plasticity chart by plotting LL &PI

CL – ML

Then the soil is SW – SC

≥15% gravel Well graded sand with clay and gravel

( or silty clay and gravel) …………….ans.

3.24e % passing #4 = 100 % retained #4 = 100-100 = 26

% passing #200 = 4 % retained (#4-#200) = 100-4 = 96

D60 = 1.87

D30 = 0.55 interpolation

D10 = 0.2

< 50% passing #200 coarse grained

< 50% retained #4 sand

< 5% passing #200 and Cu<6 or 1>Cc>3 then soil SP

< 15% gravel then the soil is Poorly graded sand ………..ans.

3.25b % passing #10 = 58 LL=19

% passing #40 = 29 PL=12

% passing #200 = 12 PI = LL-PL=7

< 35% passing #200 Granular Material

From figure 3.18 left to right we obtain the soil is

A – 2 – 4 Silty or clayey gravel and sand (excellent to good) …..ans.

3.25b % passing #10 = 62

% passing #40 = 24

% passing #200 = 4

< 35% passing #200 Granular Material

From figure 3.18 left to right we obtain the soil is

A – 1 – b Stone fragments, gravel, and sand (excellent to good) …..ans.