Log–normal, normal, exponential, gamma, and
Weibull distributions were fitted to the joint spacing
frequency distributions for each joint type in each
weathering grade Table 8.. Unless otherwise noted,
results reported in this section are at the 90% confidence
level. Examples of the distributions for each
joint type are in Fig. 9. None of the five distributions
fit the horizontal joint spacing distribution in fresh
granite. The MW and SW granite distributions could
be anything except gamma, but it is likely that the joint spacings in HW granite are from a log–normal
distribution. There are no good fits at the 99%
confidence level between any of the five distributions and vertical joint spacings in HW, MW or fresh
granite, but it is likely that the spacings in CW
granite come from a log–normal distribution and that
spacings in SW granite are from an exponential
distribution. For dipping joints, spacings in fresh
granite might be from any of the distributions except
gamma; no distribution fits the spacing data for
dipping joints in MW granite 99% confidence level.;
and the dipping joint spacings in HW granite could
come from log–normal, exponential or Weibull distributions.
The distributions were also compared with each
other using the K–S statistic. These results are shown
in Table 9. Significant differences were identified for
vertical joint spacings in CW granite and all other
weathering grades, and in MW granite and all other
weathering grades. The only distributions not significantly
different are those for HW granite and fresh
granite. None of the distributions for horizontal joint
spacing are significantly different and, for dipping
joints, only the distributions for MW and fresh granite
is significantly different.