Rock Mass Dynamic Test Apparatus for Estimating the Strain-Dependent Dynamic Properties of Jointed Rock Masses

Abstract

A rock mass dynamic test (RMDT) apparatus was developed to estimate the strain-dependent dynamic properties (i.e. shear modulus and damping ratio) of jointed rock masses over a wide range of shear strains from 10(-5) % to 10(-2) %. The resonance and equipment-generated damping of the apparatus were investigated in detail. The dynamic properties obtained from the quasi-static resonant column tests were in agreement with those of the RMDT apparatus, which suggests that the developed RMDT apparatus is valid. Furthermore, the experimental test results on gneiss discs demonstrated that the dynamic properties of jointed rock masses are stress-dependent and strain-dependent, with similar trends to those of soil, whereas the elastic threshold strain of a jointed rock is significantly lower than that of soil.