Loading Rate Dependency of Uniaxial Compressive Strength of Rock Under Water-Saturated Condition

Abstract

Moisture has various effects on the behaviour of rocks. It is well known that the compressive strength decreases significantly with an increase of moisture content. Though many studies have been carried out concerning the effect of moisture, the influence on the time dependent behaviour is still open to discussion. It is very important to clarify its time dependence for analysing the long-term stability or durability of underground structures. In this study, six rocks were tested in uniaxial compression under four loading rates C =−10−6, 10−5, 10−4 and 10−3/sec With an increase of loading rate, it was found for all samples that the strength increased and the stress-strain curve in the post-failure region shifted to the right-hand side. The slope of the stress-strain curve, however, did not change meaningfully with loading rate. It should be noted that the increase of strength with loading rate did not depend on moisture content. The constitutive equation which is applicable to various time dependent behaviours was used to simulate the loading rate dependence under uniaxial compression tests. It was found that the calculated results gave a good approximation to the experimental results for all sample rocks. © 1992, The Society of Materials Science, Japan. All rights reserved.