| Title |
Evaluation for Applications of Displacement Criterion by the Critical Strain of Uniaxial Compression in Rock Mass Tunnel |
| Keywords |
critical strain;failure strain;failure ratio(R?);M value;한계변형률;파괴변형률;파괴비(R?);M값 |
| Abstract |
Laboratory compressive test was conducted on 6 different types of rock in order to investigate the characteristic of critical strain under uniaxial and triaxial stress condition. The results of uniaxial compressive test mostly ranged within 1~100㎫, the critical strain was also located between 0.1~1.0%. Therefore the results distributed within the upper and lower boundary proposed by Sakurai (1982). And the failure/critical strain ratio (ε<SUB>?</SUB>/ε<SUB>0</SUB>) showed between 1.0~1.8 value depending on the uniaxial compressive strength. The results of critical strain by triaxial compressive test showed below 0.8% value for all test, the M value calculated from uniaxial and triaxial compressive test results ranged 1.0~8.0 for most of rock specimens. It is concluded that failure strain (ε<SUB>?3</SUB>) of rock mass, which is in triaxial stress condition is larger than the results of uniaxial stress condition (ε<SUB>?1</SUB>) by 1.0~8.0 times and value showed 1.0~1.8 larger value than critical strain (ε<SUB>01</SUB>). Therefore it is a conservative way for rock tunnel to use critical strain (ε<SUB>01</SUB>) calculated from a uniaxial compressive strength on tunnel displacement monitoring. |