2
Cell
0
Mean
Stress
Figure 1 - Stress Redistribution, Weak Soil with Stiff Cell
As can be seen there is a stress concentration at the rigid rim but in the center of the cell the soil
stress is only slightly higher than the mean soil stress, i.e., only slightly higher than the stress
which would obtain were the cell not present.
In a stronger soil, the destressed zone around the edge of the cell is more extensive; therefore, the
degree of
over registration
of the mean stress is greater at the center of the cell. This is
represented schematically in Figure 2.
Cell
0
Mean
Stress
Figure 2 - Stress Redistribution, Strong Soil with Stiff Cell
In a stiff soil the cell may be less stiff (more compressible) than the soil, in which case the cell
will
under register
the mean soil stress as the stresses in the soil tend to "bridge" around the cell.
This is represented schematically in Figure 3.
Cell
0
Mean
Stress
Figure 3 - Stress Redistribution, Stiff Soil with Weak Cell
