ABSTRACT
Critical strain, defined as the ratio of the uniaxial strength and Young’s modulus, has practically been adopted as a criterion to assess the stability of underground structures such as tunnels. It has already been demonstrated that the critical strain is more or less independent from the specimen size. This implies that the critical strain of large rock masses can be determined from a small specimen tested in the laboratory. In this study some laboratory tests were carried out to investigate environmental effects on critical strain such as confining pressure, moisture content and temperature. In this paper the results of the tests are shown, and the environmental effects are discussed.
