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 distribution <strong>an</strong>d variation <strong>of</strong> natural moisture content at depths <strong>of</strong> less th<strong>an</strong> 0,50m across<br />
the study area are characterised by a maximum <strong>an</strong>d minimum <strong>of</strong> 34% <strong>an</strong>d 18%, giving a r<strong>an</strong>ge<br />
<strong>of</strong> 16% (Table 8.1). Also characteristic are medi<strong>an</strong>, mode <strong>an</strong>d me<strong>an</strong> values <strong>of</strong> 23% as well as<br />
a st<strong>an</strong>dard deviation <strong>of</strong> 3,37 <strong>an</strong>d vari<strong>an</strong>ce <strong>of</strong> 11,36. The distribution is similar at depths <strong>of</strong><br />
0,50m <strong>an</strong>d greater, with maximum <strong>an</strong>d minimum values <strong>of</strong> 32% <strong>an</strong>d 17% giving a r<strong>an</strong>ge <strong>of</strong><br />
15% (Table 8.1). However, a slight increase in moisture content with depth <strong>of</strong> soils occurs<br />
(due to reduced drying effects), <strong>an</strong>d is reflected by a medi<strong>an</strong> <strong>of</strong> 25%, mode <strong>of</strong> 29% <strong>an</strong>d me<strong>an</strong><br />
<strong>of</strong> 25%. Also calculated for this depth are a st<strong>an</strong>dard deviation <strong>of</strong> 3,56 <strong>an</strong>d a vari<strong>an</strong>ce <strong>of</strong><br />
12,69.<br />
The variation <strong>of</strong> natural moisture content <strong>of</strong> soils at the two depth intervals across the study<br />
area is generally similar, so that the two sets <strong>of</strong> data give a covari<strong>an</strong>ce <strong>of</strong> 9,71 <strong>an</strong>d a strong<br />
correlation <strong>of</strong> 0,83 (Table 8.1).<br />
The upper 50cm <strong>of</strong> red soils were found to exhibit a relatively elevated moisture content <strong>of</strong><br />
38-39%, most probably a result <strong>of</strong> recent rainfall. However, depths greater th<strong>an</strong> 0,50m are<br />
generally characterised by a moisture content <strong>of</strong> 24-26%.<br />
8.2 Liquid limit<br />
The distribution <strong>of</strong> liquid limit values across the study area is presented in Figures (8.3a & b),<br />
which show a concentration about a me<strong>an</strong> <strong>of</strong> 84% <strong>an</strong>d 86%, respectively.<br />
Liquid limit variation; < 0,50m depth<br />
Liquid limit (%)<br />
100<br />
90<br />
80<br />
70<br />
60<br />
50<br />
40<br />
30<br />
20<br />
10<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 8.3a. Liquid limit variation across the study area for the depth <strong>of</strong> less th<strong>an</strong><br />
0,50m (north-south dist<strong>an</strong>ce: 4000 m).