an engineering geological characterisation of tropical clays - GBV

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Black clays
Cohesion c´ (kN/m²)
60,00
50,00
40,00
30,00
20,00
10,00
0,00
n = 41
Cohesion vs Cr
1 1,1 1,2 1,3 1,4 1,5 1,6
Rel. Consistency, Cr
Figure 7.6c. Correlation between cohesion (c´ ) and relative consistency, Cr,
of black clays.
A poor correlation (R = 0,30) is obtained by relating shear angles and plasticity indices of the
clays (Fig. 7.7a). A slight improvement in correlation is obtained by plotting the shear angles
against the reciprocal of plasticity indices (Fig. 7.8a); but once again, the strength of
correlation is still low (R = 0,32).
Black clays
Angle of shear resistance
φ´ (°)
35
n = 41 R² = 0,09
30
25
20
15
10
35,015 40,015 45,015 50,015 55,015 60,015
Plasticity index PI (%)
Shear angle vs PI
Figure 7.7a. Correlation between angle of shear resistance (φ´ ) and plasticity
index (PI) of black clays.