In Fig. 8.13, the data from Table 8.2 have been plotted on a semi-log plot. This curve has a characteristic
shape, which has been termed a Type 1 curve (Leonards and Altschaeffl, 1964). In Fig. 8.13,
the two straight line segments have been extended and the intersection point is at Uavg = 100 percent,
i.e., when the primary consolidation settlement is complete. The plot in Fig. 8.13 is known as the
log-of-time method, which has been introduced in Sec. 8.2.2.
In Fig. 8.14, the data from Table 8.2 have been plotted on a square root of time factor plot. Note
in Fig. 8.14 that the time factor is essentially a straight line for an average degree of consolidation
from 0 to 60 percent. This is because the equation for Uavg versus time factor T (listed at the bottom
of Table 8.2) can be rearranged such that Uavg is equal to the square root of T. If a line is drawn
such that it is placed at a distance of 0.15d (as illustrated in Fig. 8.14), it will intersect the curve at
an average degree of consolidation equal to 90 percent. This plot in Fig. 8.14 is known as the
square-root-of-time method, which was also introduced in Sec. 8.2.2.