an engineering geological characterisation of tropical clays - GBV
an engineering geological characterisation of tropical clays - GBV
an engineering geological characterisation of tropical clays - GBV
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The results <strong>of</strong> correlation show that liquid limit, LL, would be a better estimator <strong>of</strong> the<br />
compression index <strong>an</strong>d compressibility <strong>of</strong> soils th<strong>an</strong> the plasticity index, PI, (Table 7.15b).<br />
The strength <strong>of</strong> correlation between cc <strong>an</strong>d LL is very high (R = -0,85) for the black <strong>clays</strong>; but<br />
is reduced to moderate (R = -0,58) for combined black <strong>clays</strong> <strong>an</strong>d red soils (Figs. 7.23 <strong>an</strong>d<br />
7.24). The relationships between compression index <strong>an</strong>d liquid limit take the form <strong>of</strong><br />
cc = 0,0099(122-LL) (7.47)<br />
for black <strong>clays</strong>, <strong>an</strong>d<br />
cc = 0,0016(308-LL) (7.48)<br />
for both black <strong>clays</strong> <strong>an</strong>d red soils.<br />
Table 7.15b. Results <strong>of</strong> compression indices correlated with Atterberg limits.<br />
Sample No. Load<br />
(kPa) Wn (%) LL (%) PI (%) Cc Approx. Compressibility<br />
SA2-70cm 100-2400 34 90 54 0,3 medium-high<br />
SA37-50cm 25-1600 22 83 44 0,4 medium-high<br />
SB1-70cm 50-2400 30 90 51 0,29 medium-high<br />
SB42-50cm 100-2400 21 91 47 0,34 medium-high<br />
SC17-50cm 100-2400 22 81 48 0,44 medium-high<br />
SC29-50cm 100-2400 20 80 43 0,38 medium-high<br />
RD1-30cm 12,0-2400 39 49 18 0,42 medium-high<br />
RD1-100cm 12,0-2400 24 51 21 0,4 medium-high<br />
RD1-400cm 12,0-2400 25 48 18 0,39 medium-high<br />
Correlations (R) Black & red soils -0,58 -0,55<br />
Correlations (R ) Black <strong>clays</strong> only -0,85 -0,66<br />
Results <strong>of</strong> correlations <strong>an</strong>d <strong>an</strong>alysis show that cc values generally decrease with increasing<br />
liquid limit <strong>an</strong>d plasticity index <strong>of</strong> soils ( Table 7.15b; Figs. 7.23 & 7.24). This serves to<br />
suggest that compressibility <strong>of</strong> soils generally decreases with increased plasticity, <strong>an</strong>d vice<br />
versa.