Cranfield University

Appendix
closely agree with the real data. Overall the approach by O’Sullivan et al. (1998) to set the
confining pressure in relation to the axial load appears justified.
Depth (mm)
0
100
200
300
400
500
600
700
800
Soil Displacement (mm)
0 50 100 150 200
900 Weak
900 Dense
Averageof 5 Dense
Average of 5 Weak
Average of 3 Dense
Average of 3 Weak
Average of Dense Dense
Average of Dense Weak
Figure 41: Predicted and measured (Antille, 2006) soil displacement on denser and
weakr soil conditions for the 900/10.5/1.9
11.1.6 VCL from Plate Sinkage Data from Triaxial Cell
As it proved to be difficult to gain a virgin compression line describing the soil in such a way
as the tyre experiences it, a different approach to gain a virgin compression line was to use the
contact patches, pressures and sinkage data of Section 6.3. Similar to the soil bin a uniform
soil density increase over the entire depth was assumed as no sideways movement of the soil
could be detected. Again the punching type of soil failure appeared in all measurements and is
shown in Figure 42. No heave is visible at the surface indicating hardly sideways movement
of the soil. The plate sinkage experiment was conducted as specified in Section 2.8.
The virgin compression line of the soil was calculated in the same way as for the tyre data.
The plate sinkage divided by soil depth resulted in the average increase of soil density
assuming uniformity with depth. With the average increase and the known initial density the
final density was calculated and then 2.66 divided by it to gain the relative density. As with
the soil bin, contact pressure was transformed into mean normal pressure as shown in Section
6.3.3 and the resulting virgin compression line is shown in Figure 43. The function for the
different plates (left hand side of Figure 43) indicates a slightly weaker soil as the one for the
same plate with different loads on the right hand side.
Ph.D. Thesis Dirk Ansorge (2007)
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