CHAPTER 4: RESULTS AND DISCUSSION
4.15. Concluding Remarks
40
Cc = 0.016Ip - 0.446 SANH, Khulna; (Fig. 4.36)
Cc = 0.007Ip- 0.015 Combination of Bhulta & Khulna; (Fig. 4.37) The relationship between compression index and plastic limit that was established by some authors including the present study is shown in Figure 4.49. The relationships that are developed for soft and stiff soil is followed the similar trend. Comparing to the other authors’ correlations (Fig. 4.49), similar type of linear relations are found.
41
- Comparing the new relationship between qu and N-value with previous correlations done by other authors, it is observed that correlation is not unique.
It varies for different type of soils for different locations.
- The linear empirical relationship is found between compression index and initial void ratio. All empirical relations including present and previous study are more or less followed the same trend. Therefore relation from this study can be used for soils of Bangladesh. So this relation could be used for all type of clay soil.
- The correlation which was developed for compression index and natural moisture content could be used for all category of soil.
- The linear correlations were developed between compression index and liquid limit for different types of soils that vary for stiff or soft soil. However, no generalized relationship is observed comparing to the previous relationship.
- Comparing to the other authors’ correlations, between compression index and plastic limit similar type of linear relations are found.
42
Table 4.1: USCS Classification of soil samples collected from Bhulta, Narayanganj.
Sample depth
(m)
Sample ID
Sand Fraction
(%)
Liquid Limit
(LL)
Plastic Limit
(PL)
Colour of sample
USCS Classification
2.90 UD-6 6.5 56 17 Brown Fat Clay (CH)
3.81 UD-8 1.8 58 16 Brown Fat Clay (CH)
4.73 UD-10 4.0 56 14 Brown Fat Clay (CH)
5.18 UD-11 2.5 65 22 Brown Fat Clay (CH)
5.64 UD-12 4.0 44 14 Brown Lean Clay (CL)
6.55 UD-14 18.0 38 19 Brown Lean Clay (CL)
7.01 UD-15 14.4 47 15 Brown Lean Clay (CL)
7.93 UD-17 8.8 48 18 Brown Lean Clay (CL)
9.30 UD-20 24.8 30 11 Brown Lean Clay with
Sand (CL)
10.21 UD-22 13.4 45 19 Brown Lean Clay (CL)
11.13 UD-24 22.2 44 14 Brown Lean Clay with
Sand (CL)
11.60 UD-25 8.9 56 25 Brown Fat Clay (CH)
12.04 UD-26 6.2 63 23 Brown Fat Clay (CH)
12.96 UD-28 38.3 25 11 Brown Sandy Lean Clay
(CL)
43
Table 4.2: USCS Classification of soil samples collected from AMC Site, Khulna.
Sample depth (m)
Sample ID
Sand Fraction
(%)
Liquid Limit
(LL)
Plastic Limit
(PL)
Colour of Sample
USCS Classification
0.46 UD-1 0.8 56 23 Dark Gray Fat Clay (CH)
1.83 UD-4 0.3 52 24 Dark Gray Fat Clay (CH)
3.20 UD-7 0.6 44 22 Dark Gray Lean Clay
(CL)
4.57 UD-10 1.9 80 38 Black Organic Clay
(OH)
5.95 UD-13 0.8 57 27 Dark Gray Fat Clay (CH)
7.32 UD-16 0.6 32 16
Dark Gray Lean Clay (CL)
Table 4.3: USCS Classification of soil samples collected from SANH site, Khulna.
Sample depth (m)
Sample ID
Sand Fraction
(%)
Liquid Limit
(LL)
Plastic Limit
(PL)
Colour of sample
USCS Classification
0.46 UD-1 0.2 53 24 Dark Gray Fat Clay (CH)
0.91 UD-2 0.3 58 28 Dark Gray Fat Clay (CH)
1.37 UD-3 0.4 30 11 Dark Gray Lean Clay (CL)
1.83 UD-4 1.1 45 19 Dark Gray Lean Clay (CL)
2.29 UD-5 0.8 44 14 Dark Gray Lean Clay (CL)
2.74 UD-6 0.4 89 23 Black Organic Clay (OH)
44
Table 4.4: The value of SPT, Specific Gravity and Initial Void Ratio from SANH at Khulna
Sample depth (m)
Sample ID
SPT-N value (SANH, Khulna)
Specific Gravity Gs
Initial void ratio e0
1.37 UD-3 2 2.66 0.85
1.83 UD-4 3 2.63 1.65
2.29 UD-5 1 2.60 0.49
Table 4.5: The value of SPT, Specific Gravity, and Initial Void Ratio from AMC at Khulna
AMC, Khulna Sample depth
(m)
Sample ID SPT-N value (AMC)
Specific Gravity Gs
Initial void ratio e0
3.20 UD-7 9 2.60 0.85
4.57 UD-10 7 2.63 0.92
5.95 UD-13 8 2.62 0.96
45
Table 4.6: The value of SPT, Specific Gravity, Natural Moisture Content, Initial Void Ratio and Dry Density from Bhulta at Narayanganj.
Bhulta, Narayanganj Sample
Depth (m)
Sample ID SPT-N value (Bhulta)
Specific Gravity
Gs
Initial void ratio
e0
3.81 UD-8 5 2.51 0.70
4.73 UD-10 8 2.5 0.54
5.18 UD-11 7 2.55 0.81
5.64 UD-12 4 2.51 0.41
6.55 UD-14 6 2.55 0.58
7.01 UD-15 15 2.58 0.54
9.30 UD-20 24 2.66 0.42
10.21 UD-22 17 2.60 0.48
Table 4.7: Summary of Natural Moisture Content (ωn), Dry density () and Unconfined Compressive Strength (qu) of Soil Samples Collected from Bhulta,
Narayanganj.
Location Sample Depth
(m)
Sample ID
Natural Moisture
Content,
n (%)
SPT Dry
density,
(KN/m3)
Unconfined Compressive
Strength, qu
(kPa)
Bhulta (Narayanganj)
3.81 UD-8 27.8 5 14.5 245
4.73 UD-10 25.4 8 15.9 244
5.64 UD-12 35.3 4 13.9 86
7.01 UD-15 24.0 15 15.8 208
9.30 UD-20 15.4 24 18.4 277
10.21 UD-22 18.2 17 17.2 299
46
Table 4.8: Summary of Natural Moisture Content (n), Dry density () and Unconfined Compressive Strength (qu) of Soil Samples Collected from Khulna
Area.
Table 4.9 Relationship Chart between N-value and Unconfined Compressive Strength of Soil Sample at Bhulta, Narayanganj & Khulna Area.
Liquid Limit k Unconfined Compressive Strength, qu
(kPa) LL ≤ 50%;
(Lean Clay)
17.84 qu= 17.84N
LL ≥ 50%
(Fat Clay)
9.97 qu= 9.97N
Location Sample Depth (m)
Sample ID
n (%)
SPT (kN/m3) qu (kPa)
AMC
3.20 UD-7 39.5 7 12.6 29
4.57 UD-10 36.9 8 12.8 56
5.95 UD-13 35.9 9 13.8 57
SANH
1.37 UD-3 32.5 2 9.8 68
1.83 UD-4 22.5 3 13.9 84
2.29 UD-5 58.6 1 7.9 42
47
Table 4.10: Summary of Compression Index (Cc) of Soils of Bhulta, Narayanganj.
Table 4.11: Summary of Compression Index (Cc) of Soils of Khulna Area Location Sample Depth (m) Sample ID SPT Compression
Index, Cc
Bhulta (Narayanganj)
3.81 UD-8 5 0.161
4.73 UD-10 8 0.138
5.64 UD-12 4 0.229
7.01 UD-15 15 0.121
9.30 UD-20 24 0.090
10.21 UD-22 17 0.092
Location Sample Depth (m)
Sample ID SPT Compression
Index, Cc
AMC (Khulna)
3.20 UD-7 7 0.332
4.57 UD-10 8 0.262
5.95 UD-13 9 0.253
SANH (Khulna)
1.37 UD-3 2 0.268
1.83 UD-4 3 0.541
2.29 UD-5 1 0.189
48
Figure 4.1: Correlation between Unconfined Compressive Strength (qu) & Penetration Resistance (N) at Bhulta, Narayanganj
Figure 4.2: Correlation between unconfined Compressive Strength (qu) & Penetration Resistance (N) at Dhaka Cantonment.
qu= 16.71N R² = 0.777
0 50 100 150 200 250 300 350 400
0 5 10 15 20 25 30
Unconfined Compressive Strength qu(kPa)
Standard Penetration Resistance (N)
Unconfined Compressive Strength vs SPT
qu= 36.45N - 270.2 R² = 0.811
0 50 100 150 200 250 300 350 400
0 5 10 15 20
Unconfined Compressive Strength qu (kPa)
Standard Penetration Resistance(N)
Unconfined Compressive Strength vs SPT
49
Figure 4.3: Combined Correlation between unconfined Compressive Strength (qu) &
Penetration Resistance (N) at Dhaka Cantonment and Bhulta Narayanganj.
Figure 4.4: Correlation between unconfined Compressive Strength (qu) & Penetration Resistance (N) at SANH, Khulna
qu= 16.76N R² = 0.764
0 50 100 150 200 250 300 350 400
0 5 10 15 20 25 30
Unconfined Compressive Strength qu(kPa)
Standard Penetration Resistance (N)
Unconfined Compressive Strength vs SPT
qu= 33.88N R² = 0.916
0 50 100 150
0 1 2 3 4
Unconfined Compressive Strength qu(kPa)
Standard Penetration Resistance(N)
Unconfined Compressive Strength vs SPT
50
Figure 4.5: Correlation between Unconfined Compressive Strength (qu) & Penetration Resistance (N) at AMC, Khulna
Figure 4.6: Combined Correlation between Unconfined Compressive Strength (qu) &
Standard Penetration Resistance (N) at SANH and AMC at Khulna.
qu= 15.572N - 14.60 R² = 0.927
0 50 100 150
0 2 4 6 8 10
Unconfined Compressive Strength (qu)
Standard Penetration Restiance (N )
Unconfined Compressive Strength vs SPT
qu= 15.23N R² = 0.163
0 50 100 150
0 2 4 6 8 10
Unconfined Compressive Strength qu(kPa)
Standard Penetration Resistance (N)
Unconfined Compressive Strength vs SPT
51
Figure 4.7 Combined Relationship between Unconfined Compressive Strength (qu) &
SPT (N) at Khulna, Narayanganj and Dhaka
Figure 4.8: Correlation between Unconfined Compressive Strength (qu) & Penetration Resistance (N) (for Lean Clay when LL ≤ 50%)
qu= 16.50 N R² = 0.849
0 50 100 150 200 250 300 350 400
0 5 10 15 20 25 30
Unconfined compressive Strength qu(kPa)
Standard Penetration Resistance (N)
Unconfined Compressive Strength vs SPT
qu= 17.84N R² = 0.75
0 50 100 150 200 250 300 350 400
0 5 10 15 20
Unconfined Compressive strength qu(kPa)
Standard Penetration Resistance (N )
Unconfined Compressive strength vs SPT
52
Figure 4.9: Correlation between Unconfined Compressive Strength (qu) & Penetration Resistance (N) (for Fat Clay when LL ≥ 50%)
Figure 4.10: Relationship between SPT & Compression Index at Bhulta, N
qu= 9.97N R² = -3.13
0 50 100 150 200 250 300 350 400
0 5 10 15 20 25
Unconfined Compressive Strength qu (kPa)
Standard Penetration Resistance (N)
Unconfined Compressive Strength vs SPT
cc= -0.003N + 0.165 R² = 0.837
0.00 0.10 0.20 0.30 0.40
0 5 10 15 20 25 30
Compression Index(cc)
Standard Penetration Resistance (N) Compression Index vs SPT
53
Figure 4.11: Relationship between Compression Index & SPT at SANH, Khulna
Figure 4.12: Relationship between Compression Index & SPT at AMC, Khulna
cc= 0.176N - 0.019 R² = 0.908
0.00 0.10 0.20 0.30 0.40 0.50 0.60
0 1 2 3 4
Compression Index (cc)
Standard Penetration Resistance (N) Compression Index vs SPT
Cc = -0.039N + 0.598 R² = 0.834
0.00 0.10 0.20 0.30 0.40 0.50 0.60
6 7 8 9 10
Compression Index(cc)
Standard Penetration Resistance (N) Compression Index vs SPT
54
Figure 4.13: Combined Relationship between Compression Index & SPT at Khulna, Narayanganj and Dhaka
Figure 4.14: Relationship between Compression Index & (Ip/N) at Bhulta, Narayanganj
cc= -0.007N + 0.252 R² = 0.524
0.00 0.10 0.20 0.30 0.40 0.50 0.60
0 5 10 15 20 25
Compression Index (cc)
Standard Penetration Resistance (N) Compression Index
vs SPT
cc= 0.0123(Ip/N )+ 0.0759 R² = 0.90
0.00 0.10 0.20 0.30
0 2 4 6 8 10 12
Compression Index (cc)
Ip/N (Plasticity Index /SPT)
c
cvs I
p/N
55
Figure 4.15: Relationship between Compression Index & (Ip/N) at AMC, Khulna
Figure 4.16: Relationship between Compression Index & (Ip/N) at SANH, Khulna
cc = 1.5237(Ip/N) - 4.9549 R² = 0.84
0.00 0.10 0.20 0.30 0.40
0 1 2 3 4 5
Compression Index (cc)
Ip/N (Plasticity Index / SPT)
c
cvs I
p/N
cc = -0.0166(Ip/N) + 0.7425 R² = 0.4552
0.00 0.10 0.20 0.30 0.40 0.50 0.60
0 10 20 30 40
Compression Index (cc)
Ip/N (Plasticity Index / SPT)
c
cvs Ip/N
56
Figure 4.17: Combined Relationship between Compression Index & (Ip/N) at Khulna
& Narayanganj.
Figure 4.18: Correlation between Liquidity Index (LI) & SPT at Bhulta, Narayanganj
cc = 0.0047(Ip/N) + 0.1776 R² = 0.1435
0.00 0.10 0.20 0.30 0.40 0.50 0.60
0 10 20 30 40
Compression Index (cc)
Ip/N (Plasticity Index / SPT)
c
cvs I
p/N
LI = -0.013N + 0.373 R² = 0.472
0.00 0.30 0.60 0.90
0 5 10 15 20 25 30
Liquidity Indix (LI)
Standard Penetration Resistance (N)