Shigen-to-sozai, Vol.118, No.5,6, pp.377-384.
Effect of Strain Rate on Compressive Strength and Deformability of Granite
Weiren LINa, Yasufumi OHTAb, Manabu TAKAHASHIc and Nobutaka SUGITAd
| a. Research Center for Deep Geological Environments,
National Institute of Advanced Industrial
Science and Technology (AIST) (also at Dia Consultants Co., Ltd.), Tsukuba 305-8567, Japan b. Doctoral Program in Geoscience, University of Tsukuba, Tsukuba 305-8571, Japan c. Research Center for Deep Geological Environments, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8567, Japan d. Dia Consultants Co., Ltd. |
| Triaxial compression tests at 50 MPa confining
pressure and room temperature have been conducted
under various constant axial strain rates
ranging between 10-7s-1 and I0-3s-1 by using
dried specimens of Inada granite. The experimental
results showed that the ultimate strength,
axial strain at failure, Poisson's ratio
and anelastic energy which may be considered
as the energy required to generate new cracks
or to propagate pre-existing cracks in the
compression process, increased with increasing
strain rate. In addition, Young's modulus
and fracture angle which is the angle contained
by fracture plane and lateral section of
specimen, decreased with increasing strain
rate. By comparing the strain rate dependence of the compressive strength and elastic constants of granites determined experimentally in the present study and the previous works, it can be decided that the strain rate dependence of the different rocks showed different features although the rocks were same granites in petrologic classification. First, the compressive strength increased linearly as the logarithm of the strain rate increase at intermediate strain rate range (considered as from l0-8s-1 to l0-1s-1, approximately) in any granite. At high confining pressure, the strain rate dependence of the strength is enhanced in fine-grained granites; in contrast, the dependence is enfeebled in medium-grained granites. Secondly, the strain rate dependence of Young's modulus had more complex behaviors than that of the strength. At the intermediate strain rate range, there are three types of granites which were (1) their Young's modulus did not depend on the strain rate, (2) their modulus increased with the increase of the strain rate, and (3) their modulus decreased with the increase. |
| KEY WORDS: Granite, Strain Rate Dependence, Compressive Strength, Deformability, Triaxial Compression Test |