Relationships between joint apparent separation, Schmidt hammer rebound value, and distance to faults, in rocky outcrops, Calabria, Southern Italy

Abstract

In order to investigate how the apparent separation of jointing varies according to the distance from faults, and how the mechanical properties of rock masses depend on this distance and jointing density, a number of regression analysis were performed on the variables s (apparent joint separation), d (distance from major fault), and sh (rebound value of Schmidt hammer). The variables were measured at 380 stations distributed over a wide study area located in the Aspromonte range in Calabria, Southern Italy. The most significant results of simple regression analysis are expressed by the formulas: s = c + F d 05 s ⁢ h = F d k s ⁢ h = 1 / c − F ⁢ s where F and c are coefficients that depend on local conditions. The expressions obtained are characterized by acceptable to good values for correlation coefficient r (|0.74|≤ r≤|0.87|) and standard deviation of residuals ε (0.01≤ ε≤0.22). The s vs. d regression law confirms previous results of regression analysis on data from granite outcrops in an area to the north of this case study, and this can therefore be regarded as a first step towards finding a generally applicable regression law.