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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167<br />
Free swell variation; 0,50m depth <strong>an</strong>d greater<br />
Free swell (%)<br />
160<br />
140<br />
120<br />
100<br />
80<br />
60<br />
40<br />
20<br />
0<br />
0 2000 4000 6000 8000 10000 12000<br />
Dist<strong>an</strong>ce along pr<strong>of</strong>ile (m)<br />
Pr<strong>of</strong>ile A<br />
Pr<strong>of</strong>ile B<br />
Pr<strong>of</strong>ile C<br />
Pr<strong>of</strong>ile D<br />
Pr<strong>of</strong>ile E<br />
Figure 8.9b. Free swell variation across the study area at depths <strong>of</strong> 0,50m<br />
<strong>an</strong>d greater (north-south dist<strong>an</strong>ce: 4000 m).<br />
The two sets <strong>of</strong> data obtained for depths <strong>of</strong> less th<strong>an</strong> 0,50m <strong>an</strong>d those <strong>of</strong> 0,50m <strong>an</strong>d over, are<br />
generally comparable <strong>an</strong>d similar in their distribution in terms <strong>of</strong> maximum <strong>an</strong>d minimum<br />
values as well as their r<strong>an</strong>ge. A slight variation is, however, exhibited in terms <strong>of</strong> the medi<strong>an</strong>,<br />
mode <strong>an</strong>d me<strong>an</strong> values as well as the st<strong>an</strong>dard deviation <strong>an</strong>d vari<strong>an</strong>ce. As a result, a<br />
covari<strong>an</strong>ce <strong>of</strong> 35,52 <strong>an</strong>d relatively weak correlation <strong>of</strong> 0,39 has also been recorded for the two<br />
sets <strong>of</strong> data. Relatively lower values <strong>of</strong> free swell <strong>an</strong>d/ or swelling capability in upper soil<br />
depths could be attributed to increased org<strong>an</strong>ic matter content.<br />
Fig. (8.10) shows a contoured representation <strong>of</strong> the above described distribution, in which<br />
patches <strong>of</strong> low swelling capabilities are associated with lateritic <strong>clays</strong>; as well as <strong>clays</strong> <strong>of</strong><br />
swampy environments <strong>an</strong>d/ or those adjacent to river valleys <strong>an</strong>d stream ch<strong>an</strong>nels with<br />
impeded drainage <strong>an</strong>d relatively higher org<strong>an</strong>ic matter content.<br />
Free swell values obtained for red soils in this study are comparatively low <strong>an</strong>d r<strong>an</strong>ge from<br />
15-20%.