Fundamental study on strength of rock under high water vapor pressure

岩石的强度受岩石的密度、裂缝的形状和方向、加载的应变和应力速率、应力状态、温度以及是否存在气相或液相水等因素的影响。许多研究人员指出，岩石的强度取决于应力腐蚀引起的亚临界裂纹扩展。应力腐蚀裂纹扩展是由于环境介质（如水）的化学作用，使裂纹尖端的应变结合减弱，有利于裂纹扩展，裂纹速度作为应力强度因子超过应力腐蚀极限时，随着水蒸气压力的增加而增大。查尔斯，克洛科夫斯基说。Mizutani等人的实验结果表明，岩石在单轴压缩试验中的强度随着大气中水蒸气压的降低而增加。因此，根据上述事实，认为岩石的强度可能受岩石周围环境的控制。为了考察非大气环境，即水、丙酮、乙醇、气相甲醇和氢作为应力腐蚀剂对岩石强度的影响，本研究在熊本安山岩上进行了10^<-3> ~ 10^6 Pa蒸汽压范围内的单轴压缩试验和盘片试验。实验结果表明，随着水蒸气压的降低，熊本安山岩的抗压强度和抗拉强度均有所提高，而水是促进二者应力腐蚀的最有效因素。由于这些材料对抗压强度的影响程度与对抗拉强度的影响程度相同，因此可以认为压应力和拉应力状态下的断裂机制几乎相同。结果表明，在氢、氩、氮、氧等无机气体环境下岩石的强度是相同水蒸气压下岩石强度的2倍。少

The strength of rocks is affected by the density, the shape and the direction of cracks, the strain and stress rate of loading, the stress state, the temperature and the existence of water in vapor phase or in liquid phase, and so on. Many researchers have indicated that the strength of rocks is dependent on the suberitical crack growth due to stress corrosion.The stress corrosion crack growth occurs because the chemical action of an environmental agent, such as water, weakens the strained bonded at crack tips and facilitates crack propagation, and the crack velocity as a stress intensity factor is exceeded the stress corrosion limit increases with increasing water vapor pressure. Charles, Krokosky et at. and Mizutani et al. have shown the experimental results that the strength of rocks under uniaxial compression test increases with decreasing water vapor pressure in atmosphere. Accordingly, it is considered that the strength of rocks may be controlled by surrounding environment of roc … More ks, based on the above facts.In this research, to examine the influence of non-atmospheric environment, namely water, acetone, ethanol, methanol in vapor phase and hydrogen as the stress corrosion agent, on the strength of rock, uniaxial compression test and disc lest under the vapor pressure of the range from 10^<-3> to 10^6 Pa are conducted on Kumamoto andesite.From the experimental results, it is made clear that tie compressive and tensile strength of Kumamoto andesite increases with decreasing the water vapor pressure and that water is tie most effective agent which promotes the stress corrosion among them. Since the degree of influence of these materials on the compressive strength is the same as that on the tensile strength, it is considered that the mechanism of the fracture under compressive and tensile stress state is almost the same. Finally, it is shown that the strength of rock under inorganic gas environment, like hydrogen, Argon, nitrogen and oxygen, is two times as much as that under the same water vapor pressure. Less