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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163<br />
(8.6). The few isolated patches <strong>of</strong> relatively low plasticity values imply areas <strong>of</strong> increasingly<br />
lateritic <strong>clays</strong> <strong>an</strong>d/ or swampy environments .<br />
PI%<br />
Plasticitx index (PI) variation (< 0,5m)<br />
1°19´S 41 54 45 43 47<br />
4000<br />
(m)<br />
Pr<strong>of</strong>ile dist<strong>an</strong>ce (m)<br />
46<br />
3000<br />
47 48 44 39 47 47 46<br />
47 47 48 43 47 49 44<br />
2000<br />
West<br />
48 48 47 49 46 48 47<br />
1000<br />
1°21.5´S48 48 48 41 49 49 49<br />
0<br />
47<br />
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 (m)<br />
36°49´E<br />
South<br />
Pr<strong>of</strong>ile dist<strong>an</strong>ce (m) 36°55´E<br />
49<br />
48.5<br />
48<br />
47.5<br />
47<br />
46.5<br />
%<br />
46<br />
45.5<br />
45<br />
44.5<br />
44<br />
43.5<br />
43<br />
42.5<br />
42<br />
41.5<br />
41<br />
40.5<br />
Plasticity index (PI) variation (> 0,5m)<br />
1°19´S 39 55 47 39 49<br />
4000<br />
(m)<br />
Pr<strong>of</strong>ile dist<strong>an</strong>ce (m)<br />
48 49 51 49 45 51 50 49<br />
3000<br />
50 50 49 39 49<br />
2000<br />
48 47<br />
West<br />
50 49 49 49 47 48 48<br />
1000<br />
1°21.5´S48 47 48 48 48 43 50<br />
0<br />
47<br />
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 (m)<br />
36°49´E<br />
South Pr<strong>of</strong>ile dist<strong>an</strong>ce (m)<br />
36°55´E<br />
41.5<br />
42<br />
42.5<br />
43<br />
43.5<br />
44<br />
44.5<br />
45<br />
45.5<br />
46<br />
46.5<br />
47<br />
47.5<br />
48<br />
48.5<br />
49<br />
49.5<br />
50<br />
PI%<br />
50.5<br />
Figure 8.6. A contoured representation <strong>of</strong> the distribution <strong>an</strong>d variation <strong>of</strong> plasticity index<br />
values in black <strong>clays</strong>.<br />
The two depth intervals show more or less similar plasticity values <strong>an</strong>d parameters, implying<br />
a more or less uniform <strong>an</strong>d/ or homogeneous character <strong>of</strong> the black <strong>clays</strong>, both across the<br />
study area <strong>an</strong>d with depth. This is further evidenced by a covari<strong>an</strong>ce <strong>of</strong> 5,60 <strong>an</strong>d a fairly<br />
strong correlation <strong>of</strong> 0,63 between the two sets <strong>of</strong> data obtained for the two depth intervals<br />
(Table 8.1).<br />
The plasticity indices obtained for the red soils in this study are relatively low, r<strong>an</strong>ging from<br />
18-22%.