c)
Figure 7. Plot of the key experimental output from the SRST. (a) FFc and
σu, (b) σt and packing density, and (c)
φ and τpre.
4.1.4 Relative contribution of tensile strength and
friction on unconfined yield
strength
Next, the relative contribution of the tensile and frictional components
on the unconfined yield strength are explored. The stress contribution
due to the frictional component \(\sigma_{f}\) is calculated by
subtracting tensile strength from the unconfined yield strength:
\(\sigma_{f}=\sigma_{u}-\sigma_{t}\) (5)
It is important to note that this frictional component is different from
the internal angle of friction and the shear stress. It is a fictitious
contribution of friction to unconfined yield strength in the normal
direction.
Figure 8 shows the relationship between the frictional and tensile
contributions to the total unconfined yield strength. Both the friction
and tensile strength contribute to the unconfined yield strength, and
the contribution of friction is slightly higher than that of tensile
strength. It is also noted that the frictional strength follows the
trend of internal angle of friction and τpre as shown in
Figure 7c.