Environmental Engineering Reference
In-Depth Information
Figure 6.9 presents the details of contact between clay aggregations and silt
grains in a clay-rich zone, with apparent clay bridges and obvious inter-grain linking
action.
6.2.3.
Collapse behavior of the loess
The collapse susceptibility of the samples was first characterized at natural water
content using Knight's simple oedometer method [KNI 63], as seen in Figure
6.10. This method consists of loading the sample at natural water content (up to
200 kPa) and then soaking the sample under 200 kPa. According to the volume
decrease observed during this test, various degrees of susceptibility, starting from
non-collapsible (0-1%) to very collapsible (10-20%), have been defined by Knight,
as presented in Table 6.2.
1.00
h = 2.2 m
Waterflooding
0.90
h = 3.5 m
0.80
h = 1.2 m
h = 4.9 m
0.70
0.60
1
10
100
1000
Vertical stress (kPa)
Figure 6.10.
Collapse test, simple oedometer method
Collapse strain under
200 kPa (%)
Susceptibility
Evaluation
samples at 1.2, 3.5 and
4.9 m
0-1
non-collapsible
1-5
slightly collapsible
sample at 2.2 m
5-10
collapsible
10-20
very collapsible
Table 6.2.
Knight's criteria [KNI 63]
