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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by differences in lithology, mineralogy <strong>an</strong>d/ or org<strong>an</strong>ic matter content between <strong>tropical</strong> soils<br />
as encountered in this study, <strong>an</strong>d those <strong>of</strong> temperate climates on which Skempton´s <strong>an</strong>alysis<br />
<strong>an</strong>d derivation were based. This leaves the new relationships developed in this study as better<br />
<strong>an</strong>d preferred estimators <strong>of</strong> compressibility characteristics <strong>of</strong> soils using laboratory measured<br />
liquid limits.<br />
Table 7.16. Correlation: calculated <strong>an</strong>d laboratory derived compression indices.<br />
Sample No. Load kPa Wn (%) LL (%) PI (%) Cc Cc(b) Cc(br) Cc(Sk)<br />
SA2-70cm 100-2400 34 90 54 0,30 0,32 0,35 0,72<br />
SA37-50cm 25-1600 22 83 44 0,40 0,39 0,36 0,66<br />
SB1-70cm 50-2400 30 90 51 0,29 0,32 0,35 0,72<br />
SB42-50cm 100-2400 21 91 47 0,34 0,31 0,35 0,73<br />
SC17-50cm 100-2400 22 81 48 0,44 0,41 0,36 0,64<br />
SC29-50cm 100-2400 20 80 43 0,38 0,42 0,36 0,63<br />
RD1-30cm 12,0-2400 39 49 18 0,42 0,41 0,35<br />
RD1-100cm 12,0-2400 24 51 21 0,40 0,41 0,37<br />
RD1-400cm 12,0-2400 25 48 18 0,39 0,42 0,34<br />
Correlations (R ) Black <strong>clays</strong> only 0,85<br />
Correlations (R ) Black <strong>clays</strong> & red soils 0,58<br />
Future works could attempt to perform correlations between laboratory determined<br />
compression indices <strong>an</strong>d index properties, based on a larger amount <strong>of</strong> data th<strong>an</strong> is currently<br />
available in this study. This would serve to indicate possible improvements in the strength <strong>an</strong>d<br />
reliability <strong>of</strong> correlations, as well as assessment <strong>of</strong> compressibility characteristics <strong>of</strong> the soils<br />
based on laboratory measured index properties.<br />
So far, it c<strong>an</strong> be safely stated that laboratory determined liquid limits could be used to<br />
approximately estimate the compression indices <strong>an</strong>d , therefore, assess compressibility<br />
characteristics <strong>of</strong> the black <strong>clays</strong> <strong>an</strong>d red soils found.<br />
Values <strong>of</strong> secondary compression ,cα, obtained for black <strong>clays</strong> <strong>an</strong>d red soils are given in Table<br />
(7.17), <strong>an</strong>d have been used to classify the soils into various groups. Typical values <strong>of</strong> cα for<br />
other types <strong>of</strong> soil (after Lambe <strong>an</strong>d Whitm<strong>an</strong>, 1979) are also included for comparison<br />
purposes. The black <strong>clays</strong> fall in the class <strong>of</strong> normally consolidated <strong>clays</strong> while the red soils<br />
are classified as normally consolidated to slightly overconsolidated.
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