Strength weakening effect of high static pre-stressed granite subjected to low-frequency dynamic disturbance under uniaxial compression
(1. Engineering Research Center of Safety and Protection of Explosion & Impact of Ministry of Education (ERCSPEIME), Southeast University, Nanjing 211189, China;
2. School of Civil Engineering, Southeast University, Nanjing 211189, China;
3. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China)
2. School of Civil Engineering, Southeast University, Nanjing 211189, China;
3. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China)
Abstract: This study aimed to elucidate the strength weakening effect of high static pre-stressed rocks subjected to low-frequency disturbances under uniaxial compression. Based on the uniaxial compressive strength (UCS) of granite under static loading, 70%, 80%, and 90% of UCS were selected as the initial high static pre-stress (σp), and then the pre-stressed rock specimens were disturbed by sinusoidal stress with amplitudes of 30%, 20%, and 10% of UCS under low-frequency frequencies ( f ) of 1, 2, 5, and 10 Hz, respectively. The results show that the rockburst failure of pre-stressed granite is caused by low-frequency disturbance, and the failure strength is much lower than UCS. When the σp or f is constant, the specimen strength gradually decreases as the f or σp increases. The experimental study illustrates the influence mechanism of the strength weakening effect of high static pre-stress rocks under low-frequency dynamic disturbance, that is, high static pre-stress is the premise and leading factor of rock strength weakening, while low-frequency dynamic disturbance induces rock failure and affects the strength weakening degree.
Key words: deep rock; high static pre-stress; low-frequency dynamic disturbance; strength weakening effect; uniaxial compression; rockburst