. The gradation curves of three soils are shown in the following figure. Note th
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Question
. The gradation curves of three soils are shown in the following figure.
Note
that the x-axis has particle sizes increasing from left to right.
(i)
What are the appropriate names for soils A, B, and C, and regions X, Y, and Z
(ii)
Determine the textural composition of each soil.
(iii)
Calculate effective particle size, median particle size, coefficient of uniformity, and
coefficient of gradation for each soil.
(iv)
Do the results confirm the names you choose for soils A, B, and C in part (i)? If not,
after part (ii) and (iii), what better names would you provide for soils A, B, and C?
02. The gradation curves of three soils are shown in the following figure. 40 10 4ip.¾in. 3in. No. 200 100 100 80 -60 40 20 0 10 100 0.001 0.01 0.1 Grain diameter (mm)Explanation / Answer
(i)A=Gap graded (Excess of certain particles & deficiency of others)
B=Uniformly graded (Most of the particles are of the same size)
C=Well graded soil (Soil contains good representations of particles of all sizes)
X=0.001mm-0.074mm
Silt
Y=0.074mm-4.75mm
Sand
Z=4.75mm-4.85mm
Gravel
(ii)Gravel(Z)
Well graded gravel(GW)
Sand(Y)
Well graded sand(SW)
(iii)A
D10(Effective particle size)=0.02
D30=0.05
D60=1.25
Cu(Coefficient of uniformity)=D60/D10
=1.25/0.02
=62.5
D50(Median particle size)=0.45
Cc(Coefficient of curvature or Coefficient of gradation)=(D30)^2/(D60*D10)
=(0.05)^2/(1.25*0.02)
=0.1
B
D10(Effective particle size)=0.3
D30=0.45
D60=0.6
Cu(Coefficient of uniformity)=D60/D10
=0.6/0.3
=2
D50(Median particle size)=0.5
Cc(Coefficient of curvature or Coefficient of gradation)=(D30)^2/(D60*D10)
=(0.45)^2/(0.6*0.3)
=1.125
C
D10(Effective particle size)=0.02
D30=0.6
D60=8
Cu(Coefficient of uniformity)=D60/D10
=8/0.02
=400
D50(Median particle size)=4.75
Cc(Coefficient of curvature or Coefficient of gradation)=(D30)^2/(D60*D10)
=(0.6)^2/(8*0.02)
=2.25
(iv)
Correct names only
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