Strain Rate Behaviour of Three Rocks in Tension

The paper presents the dynamic characterization in tension of three rocks under medium
and high strain-rates. The tests have been carried out by means of the JRC-Split Hopkinson
Tension Bar and an Hydro-Pneumatic Machine, installed in the DynaMat Laboratory of the
University of Applied Sciences of Southern Switzerland. The dynamic direct tension tests have
been performed at 3 different strain rates (0.1, 10, 100 strain/second) on an orthogneiss, for
loading directions 0◦, 45◦ and 90◦ respect to the schistosity, and two different types of marble.
Results of the tests show a significantly strain-rate sensitive behaviour, exhibiting dynamic
tensile strength increasing with strain-rate. In order to describe the strain rate behaviour of
these rocks, the dynamic increase factors in function of the strain rates for tensile strength
have been used.